Co-reporter:Xiaohui Meng and Dong Qiu
Langmuir March 25, 2014 Volume 30(Issue 11) pp:3019-3023
Publication Date(Web):March 3, 2014
DOI:10.1021/la404944w
Centimeter-sized two-dimensional (2D) colloidal single crystals of polystyrene (PS) particles were fabricated at the water/air interface by capillary-modulated self-assembly. Different from previous reports, in this work, emulsifier was used to facilitate the stress release during 2D colloidal crystal formation by adjusting the interparticle lateral interactions. With the assistance of compressed nitrogen flow, 2D hexagonal colloidal single crystals of centimeter size were obtained under appropriate emulsifier concentrations. A new method was also developed to transfer the 2D colloidal crystals from the air/water interface to the desired substrate without obvious disturbance. This new transferring method was proven not to be sensitive to surface wettability nor curvature, thus 2D colloidal single crystals with large areas could be obtained on different kinds of substrate.
Co-reporter:Feiyan Zhu;Chen Wang;Saina Yang;Qian Wang;Fuxin Liang;Chenyang Liu;Xiaozhong Qu;Zhongbo Hu;Zhenzhong Yang
Journal of Materials Chemistry B 2017 vol. 5(Issue 13) pp:2416-2424
Publication Date(Web):2017/03/29
DOI:10.1039/C7TB00384F
In this work, an injectable composite hydrogel was synthesized via a unique way of crosslinking glycol chitosan (GC) with silica nano-particles (SiNP) through non-chemical interactions, and was then applied as a kind of wound dressing. Gelation was achieved through the incorporation of SiNPs with the GC segments in aqueous solution, therefore strictly confining the movement of the solubilized polymer chains. Rheology tests showed that the sol–gel transition and the moduli of the hydrogel were influenced by the composition of the two components, the size of the nano-particles and the conformation of the polymers. Using such a strategy, tissue adhesion properties of GC were well-preserved in the GC/SiNP hydrogel and therefore it gains gluey properties toward biological tissues as demonstrated through the adhesion of two pieces of mouse skin, obtaining a lap-shear stretching force of ca. 90 kPa. This characteristic, together with the injectability, allowed the hydrogel to be administrated directly on the wound site and to fill the wound area. Meanwhile, the hydrogel also works as a carrier of protein and cells. The in situ encapsulation of fibroblasts enabled the promising properties of the GC/SiNP hydrogel to be used for treating full-thickness skin defects in a mouse model, resulting in the favorable growth of hair follicles and microvessels, hence reducing the risk of scar formation.
Co-reporter:Hui-Hui Ren, Hui-Yu Zhao, Yang Cui, Xiang Ao, ... Dong Qiu
Chinese Chemical Letters 2017 Volume 28, Issue 11(Volume 28, Issue 11) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.cclet.2017.07.014
Poly(1,8-octanediol-co-citrate) (POC) represents a new promising biocompatible and biodegradable polyester that has been extensively investigated for soft tissue engineering. However, the poor mechanical performance and poor bioactivity limit its application in bone regeneration. In this study, a series of POC/bioactive glasses (BG) composites were developed using 45S5 Bioglass® and a phytic acid-derived bioactive glass (referred as PSC). The results indicated that calcium in BG could enhance the crosslinking of the POC/BG composites by forming calcium dicarboxylate bridges and thus improve their mechanical performances. When PSC were used, the composites exhibited significantly better mechanical properties compared to composites with 45S5 Bioglass®. For example, by incorporating 70 wt% PSC, the compressive strength of POC/PSC composites could be improved to approximately 50 MPa and modulus 1.3 ± 0.1 GPa. Furthermore, all these POC/PSC composites showed good in vitro bioactivity and cellular biocompatibility. Histology results in femoral condyle defects of Sprague-Dawley rats indicated that the POC/PSC samples integrated well with surrounding tissues and stimulated bone regeneration. The improved mechanical properties and bioactivity of POC/PSC composites make them promising for potential application in bone regeneration.A series of POC/bioactive glasses (BG) composites were developed using a phytic acid-derived bioactive glass. These composites exhibited improved mechanical performance and excellent biological properties, which make them promising for potential application in bone regeneration.Download high-res image (118KB)Download full-size image
Co-reporter:Feng Yan, Xinping Zhang, Huihui Ren, Xiaohui Meng, Dong Qiu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 529(Volume 529) pp:
Publication Date(Web):20 September 2017
DOI:10.1016/j.colsurfa.2017.06.005
•Patched laponite-polymer composite particles (LCPs) have been synthesized and used to reinforce the PAM hydrogel.•LC hydrogels reinforced by LCPs have shown better mechanical performance than LA hydrogels at similar particle content.•The patched surface with laponite part and CC part was the key to lead to the good performance of LC hydrogels.The application of patched laponite-polymer composite particles (LCPs) in hydrogel reinforcement has been proposed and such hydrogels (LC hydrogels) were successfully prepared. LCPs can be well dispersed in hydrogel matrix to rather high particle concentration and at the same time, form chemical bonding with polymer matrix through copolymerization of surface CC groups. The obtained LC hydrogels showed more homogeneous microstructure and significantly higher mechanical strength comparing with the hydrogel containing bare laponite or laponite surface modified with CC groups at same particle content. A series of control experiments reveals that both the surface chemistry and patched morphology were essential to produce such good reinforcement performance.Download high-res image (124KB)Download full-size image
Co-reporter:Ailing Li, Huihui Ren, Yang Cui, Chao Wang, Xiaojuan Zhou, He Lin, Dong Qiu
Journal of Non-Crystalline Solids 2017 Volume 475(Volume 475) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jnoncrysol.2017.07.027
•Detailed structure of a new bioactive glass composition (PSC) was studied.•The structure information were obtained by HEXRD and solid NMR techniques.•There is Si-O-P network formed for PSC samples but not for 45S5 and S70C30 samples.Detailed structure of a new bioactive glass composition (PSC, 54 mol% SiO2, 35 mol% CaO and 11 mol% P2O5) was studied, and conventional glasses (45S5 and S70C30) were used as comparison. The structure information were obtained by HEXRD and solid NMR techniques. It was found that all the samples have different silicon and phosphorous coordination environment, there is Si-O-P network formed for PSC samples but not for 45S5 and S70C30 samples. These results may hopefully advance the design of new bioactive glasses.
Co-reporter:Zhichao Zhu, Junfeng Xiang, Jianjun Wang, and Dong Qiu
Langmuir 2017 Volume 33(Issue 1) pp:
Publication Date(Web):December 6, 2016
DOI:10.1021/acs.langmuir.6b03374
Tuning ice formation is of great importance in biological systems and some technological applications. Many synthetic polymers have been shown to affect ice formation, in particular, polyvinyl alcohol (PVA). However, the experimental observations of the effect of PVA on ice formation are still conflicting. Here, we introduced colloidal silica (CS) as the model liquid/solid interface and studied the effect of PVA on ice formation in detail. The results showed that either PVA or CS promoted ice formation, whereas the mixture of these two (CS–PVA) prevented ice formation (antifreezing). Using quantitative analysis based on classical nucleation theory, we revealed that the main contribution came from the kinetic factor J0 rather than the energy barrier factor Γ. Combined with the PVA adsorption behavior on CS particles, it is strongly suggested that the adsorption of PVA at the interface has significantly reduced ice nucleation, which thus may provide new ideas for developing antifreezing agents.
Co-reporter:Kongli Xu, Caiyan Gao, Guangming Chen, Dong Qiu
Organic Electronics 2016 Volume 31() pp:41-47
Publication Date(Web):April 2016
DOI:10.1016/j.orgel.2016.01.013
•Effect of polymer orientation on thermoelectric performance is studied by infrared dichroism.•Film stretching led to macromolecular preferred orientation in neat PANI and its composites.•The degree of orientation increased with draw ratio, resulting in enhanced thermoelectric performance.•Obvious anisotropic thermoelectric performance was found.•Carbon nanoparticles had a significant hindrance effect on macromolecular orientation.A direct evidence by infrared dichroism is reported for the first time for the effect of molecular orientation on thermoelectric (TE) performance of organic polymer materials. The preferred orientation was induced by mechanical uni-axial stretching of the films of neat polyaniline (PANI) and its nanocomposites with reduced graphene oxide (rGO) or multi-walled carbon nanotube (MWCNT). Five characteristic bands of Fourier transform infrared (FTIR) spectra were chosen, and quantitative investigations were carried out using the dichroic ratios measured by polarized FTIR spectra. The influences of draw ratio and content of inorganic carbon nanoparticles were taken into account. The results show that the TE performance (including anisotropic TE function) can be conveniently tuned by polymer molecular orientation induced by mechanical stretching, which shed light on the understanding of molecular mechanism towards structure-TE performance relationship, and will speed up the applications of organic polymer TE materials.Direct evidence by infrared dichroism is provided to confirm the effect of molecular orientation on polymer thermoelectric performance.
Co-reporter:Xinping Zhang, Yinyan Guan, Yue Xie and Dong Qiu
RSC Advances 2016 vol. 6(Issue 10) pp:7970-7976
Publication Date(Web):13 Jan 2016
DOI:10.1039/C5RA26937G
Ceramifiable polymer composites, especially silicone rubber composites, are widely used at elevated temperatures. These composites could convert into freestanding ceramified residues at temperatures above ∼1100 °C through eutectic reactions between the pyrolyzates of polymer matrices and ceramifying agents. However, it remains challenging for polymer composites to be used at the medium high temperatures (500–900 °C), because of the gap between the temperatures of polymer decomposition and the eutectic reaction. Here, we demonstrate that when the Laponite platelets in the preformed “house-of-cards” structure (Laponite-armored hollow composite particles, referred to as LHCPs) are used as fillers for silicone rubber, the resultant composites can well maintain their shape and mechanical strength in this critical temperature range as mentioned above. As revealed by microscopic and crystallographic studies, the superb anti-collapsing performance at medium high temperatures was indicated to stem from the “house-of-cards” structure of the LHCPs. These composites may find potential in some high temperature applications, for example, fire resistance cables, where both shape-maintenance and mechanical support at medium high temperatures are required in order to ensure electric supply in fire.
Co-reporter:Zheng Yin, Jingjing Cao, Zhen Li and Dong Qiu
RSC Advances 2016 vol. 6(Issue 16) pp:13377-13383
Publication Date(Web):27 Jan 2016
DOI:10.1039/C5RA22309A
Poly(vinyl alcohol) (PVA) was used as a low-cost and degradable water retention agent in combating drought and desertification. The effect of PVA with different degrees of hydrolysis on the enhancement of water retention capacity of sandy soil and the growth performance of Arabidopsis thaliana were investigated. The results showed that PVA could effectively enhance the water retention capacity of sandy soil and the growth of plants in it. After the addition of PVA, the survival rate, aerial biomass and chlorophyll content of Arabidopsis thaliana all increased substantially compared to those in untreated soil under the condition of water shortage. The relationship between PVA's degree of hydrolysis and its water retention performance in sandy soil was also studied. It was found that PVA with a middle degree of hydrolysis, 1795 and 1797, had the best performance, which even catches up with the traditional cross-linked hydrogel-PAM, suggesting that PVA could be an effective water retention agent for improving plant growth in sandy soil and combating desertification. Through this study, a few criteria were proposed for the selection of better water retention agents, considering their water absorbency, retaining ability in sandy soil and degradability.
Co-reporter:Yong-Sen Sun, Ai-Ling Li, Hui-Hui Ren, Xin-Ping Zhang, Chao Wang, Dong Qiu
Chinese Chemical Letters 2016 Volume 27(Issue 4) pp:579-582
Publication Date(Web):April 2016
DOI:10.1016/j.cclet.2016.02.018
Bioactive calcium silicates prepared by sol–gel routes mainly use calcium nitrate as the calcium precursor. However, the toxic nitrate ions are usually removed by calcination (i.e. 550 °C or over), which poses great challenge for the in situ preparation of inorganic/polymer composites, as polymer moieties could not survive such temperatures. In this study, we prepared 70Si30Ca (70 mol% SiO2 and 30 mol% CaO) bioactive glass at low temperatures where polymer could survive (i.e. 200 °C and 350 °C), and proposed to remove the residual nitrate ions through soaking. Deionized water and simulated body fluid (SBF) were employed as the soaking medium. The results showed that the residual nitrate ions could be removed as quickly as 0.5 h while maintain the bioactivity of the samples. This technique may open the possibility of preparing sol–gel derived bioactive glass/polymer hybrids in situ with reduced potential toxicity.The nitrate ion can be rapidly removed by soaking method for only 0.5 h.
Co-reporter:Dao-hong Mei 邱东;Da-dong Yan 严大东
Chinese Journal of Polymer Science 2016 Volume 34( Issue 2) pp:195-208
Publication Date(Web):2016 February
DOI:10.1007/s10118-016-1741-4
In this paper, the continuum self-consistent field theory (SCFT) is applied to study the structure and the interaction of the adsorption of symmetrical ABA polyampholytes (PAs) between two neutral planes. It is found that the amounts of all the conformations decrease with the increase of the charge fraction of polymer chain, and increase with the increase of the bulk salt concentration and become saturated at high bulk salt concentration. The effective interaction between the two planes presented a long-range repulsion. Splitting it into various components and relating with the dependence of the variations of the conformations on environment parameters, we try to find the origin of the total long-range interaction between the two planes.
Co-reporter:Dr. Ting Huang;Liju Xu;Chen Wang;Zheng Yin; Dong Qiu
Chemistry – An Asian Journal 2016 Volume 11( Issue 2) pp:280-284
Publication Date(Web):
DOI:10.1002/asia.201501027
Abstract
A surfactant-free emulsion polymerization process was developed to produce hollow hybrid nanoparticles (HHNP thereafter). Ultrasonication was found not only to help the generation of nanosized monomer droplets but also to generate surface active species through mediating the hydrolysis of the monomer, 3-(methacryloyloxy) propyltrimethoxysilane (MPS), thus stabilizing the oil/water interface. The hollow structure was formed based on a soft template approach, where the partially hydrolyzed monomer served as emulsifier and polymerized at the interface to form a hybrid shell. These HHNPs were used to absorb dissolved toluene in water and it was found they could reduce the toluene level down to zero, a level hardly being achieved by other methods. Combined with their good colloidal stability in water, these HHNPs are very promising colloidal collectors for dissolved organic solvents, in order to generate high quality water from contaminated water.
Co-reporter:Zhichao Zhu, Xiaobiao Dong, Guanxin Zhang, Junfeng Xiang, and Dong Qiu
Langmuir 2016 Volume 32(Issue 9) pp:2145-2150
Publication Date(Web):February 22, 2016
DOI:10.1021/acs.langmuir.6b00288
The adsorption of polymer on colloidal particle has significant influence on colloid structure and dynamics. Here we introduce a new method to monitor the adsorption in situ, based on the different emission behavior of aggregation-induced emission (AIE) luminogen in different micro environments. Poly(vinyl alcohol) (PVA) and colloidal silica (CS) were used as a model system. It was found that AIE molecules exhibited extremely low fluorescence intensity in water and PVA solution, while their emission efficiency was enhanced when adsorbed on CS, and became significantly boosted when PVA was adsorbed on CS at the same time. The fluorescence intensity increases with the amount of added PVA and reaches a saturation point, which is earlier than that obtained by the well-established solvent relaxation NMR method, due to their different sensitivities for adsorption segments in specific conformation. This new method is advantageous in quick response, where the measurement can be finished within 2 min, while others usually take hours. Therefore, it is expected that this new method may be used to monitor the dynamical adsorption process of polymer on colloidal particles.
Co-reporter:Feng Yan, Lei Ye, Dong Qiu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 507() pp:67-75
Publication Date(Web):20 October 2016
DOI:10.1016/j.colsurfa.2016.07.080
•The particle/polymer number ratio has a great effect on the structure and dynamics of such complexes at constant polymer concentration.•The zero-shear viscosity of silica-PEO1 M mixture exposed an interesting decrease when much more particles were added.•The interaction between particle and polymer chains leads to the microstructure evolution of colloid-polymer mixture.The effect of particle/polymer number ratio on the structure and dynamics of particle-polymer complexes at a fixed polymer concentration has been investigated. Mixtures of poly(ethylene oxide) (PEO, Mv = 1,000,000 g mol−1, Rh ∼39 nm) aqueous solution and colloidal silica dispersion (Rh ∼10 nm) were used as models. By adding silica particles, both zero-shear viscosity and Rh of the silica-PEO complexes increased with particle/polymer number ratio. The maximum zero-shear viscosity was reached when the PEO coils were saturated by silica particles. After that, a decrease in zero-shear viscosity and Rh was observed. SAXS results showed that PEO had a great effect on the inter-particle correlations before the PEO chains were saturated with silica particles, however, this effect diminished when even more silica particles were introduced. The reversible bridging interaction and inter-particle electrostatic repulsion were identified as the major factors accounting for the change in zero-shear viscosity and hydrodynamic size, and a tentative mechanism was proposed based on the spatial distribution of silica particles in the mixtures.
Co-reporter:Ailing Li, Hong Shen, Huihui Ren, Chen Wang, Decheng Wu, Richard A. Martin and Dong Qiu
Journal of Materials Chemistry A 2015 vol. 3(Issue 7) pp:1379-1390
Publication Date(Web):22 Dec 2014
DOI:10.1039/C4TB01776E
New sol–gel functionalized poly-ethylene glycol (PEGM)/SiO2–CaO hybrids were prepared with interpenetrating networks of silica and PEGM through the formation of Si–O–Si bonds. Bioactive and mechanical properties were investigated for a series of hybrids containing varying organic/inorganic ratios and PEG molecular weights. In contrast to the unmodified PEG/SiO2–CaO hybrids, which rapidly dissolved and crumbled, the epoxy modified hybrids exhibited good mechanical properties and bioactivity. The compressive strength and Young's modulus were greater for higher molecular weight PEGM hybrids (PEGM600 compared to PEGM300). Compressive strengths of 138 MPa and 81 MPa were found for the 50:50 and 60:40 organic/inorganic hybrid samples respectively, which are comparable with cortical bone. Young's modulus values of ∼800 MPa were obtained for the 50:50 and 60:40 organic/inorganic hybrids. Bioactivity tests were conducted by immersing the hybrids into simulated body fluid and observing the formation of apatite. Apatite formation was observed within 24 hours of immersion. PEGM600 hybrids showed enhanced apatite formation compared to PEGM300 hybrids. Increased apatite formation was observed with increasing organic/inorganic ratio. 70:30 and 60:40 hybrids exhibited the greatest apatite formation. All PEGM hybrids samples had good cell viability and proliferation. The 60:40 PEGM600 hybrids displayed the optimal combination of bioactivity and mechanical strength. The bioactivity of these hybrids, combined with the enhanced mechanical properties, demonstrate that these materials have significant potential for bone regeneration applications.
Co-reporter:Yang Lv, Ailing Li, Fang Zhou, Xiaoyu Pan, Fuxin Liang, Xiaozhong Qu, Dong Qiu, and Zhenzhong Yang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 21) pp:11280
Publication Date(Web):May 13, 2015
DOI:10.1021/acsami.5b01447
Percutaneous vertebroplasty (VP) and balloon kyphoplasty (BKP) are now widely used to treat patients who suffer painful vertebral compression fractures. In each of these treatments, a bone cement paste is injected into the fractured vertebral body/bodies, and the cement of choice is a poly(methyl methacrylate) (PMMA) bone cement. One drawback of this cement is the very high exothermic temperature, which, it has been suggested, causes thermal necrosis of surrounding tissue. In the present work, we prepared novel composite PMMA bone cement where microcapsules containing a phase change material (paraffin) (PCMc) were mixed with the powder of the cement. A PCM absorbs generated heat and, as such, its presence in the cement may lead to reduction in thermal necrosis. We determined a number of properties of the composite cement. Compared to the values for a control cement (a commercially available PMMA cement used in VP and BKP), each composite cement was found to have significantly lower maximum exothermic temperature, increased setting time, significantly lower compressive strength, significantly lower compressive modulus, comparable biocompatibility, and significantly smaller thermal necrosis zone. Composite cement containing 20% PCMc may be suitable for use in VP and BKP and thus deserves further evaluation.Keywords: compressive strength; modulus; phase-change microcapsule; PMMA bone cement; setting time; thermal necrosis;
Co-reporter:Runrun Wu, Jianming Pan, Xiaohui Dai, Dong Qiu, Hengjia Zhu, Yue Ma, Weidong Shi and Yongsheng Yan
Chemical Communications 2015 vol. 51(Issue 90) pp:16251-16254
Publication Date(Web):14 Sep 2015
DOI:10.1039/C5CC06516J
Herein, we propose a facile protocol for the fabrication of biomedical microstructures with fine textures of hierarchical rippled and crumpled morphologies through double emulsions by the simple addition of interior Pickering nanoparticles.
Co-reporter:Xinping Zhang;Yinyan Guan;Yunfeng Zhao;Zhijie Zhang
Polymer International 2015 Volume 64( Issue 8) pp:992-998
Publication Date(Web):
DOI:10.1002/pi.4900
Abstract
Raspberry-like SiO2@Polymer composite particles, prepared by one-pot Pickering emulsion polymerization in aqueous medium, were used to reinforce silicone rubber. Bearing both polymer moieties and Si−OH groups on the surface, these raspberry-like particles were better dispersed in the silicone rubber matrix; therefore the mechanical performance of the resultant particle − silicone rubber composites was significantly enhanced. With 25 phr SiO2@Polymer composite particles, the tensile strength, elongation at break and hardness were 2.02 MPa, 129% and 38, respectively. Further increasing the filler amount resulted in decrease of the tensile strength and modulus. In the meantime, although there was a large fraction of polymeric phase in the composite particles, the thermal stability of the resultant particle − silicone rubber composites was not significantly reduced, especially for particle loading exceeding 10 phr. These raspberry-like SiO2@Polymer composite particles are easily produced on a large scale in an environmentally friendly and cost-effective way; thus these are promising novel fillers to reinforce silicone rubber. © 2015 Society of Chemical Industry
Co-reporter:Ting Huang;Kuncheng Yao;Teng Wu;Dr. Dong Qiu
Chemistry – An Asian Journal 2015 Volume 10( Issue 7) pp:1581-1585
Publication Date(Web):
DOI:10.1002/asia.201500297
Abstract
Seeded polymerization has been widely used to fabricate polymer-encapsulated inorganic particles (IPs). The most frequently used seeds are spherical, whereas nonspherical particles are not well documented. Recently, sheet-like IPs have attracted much attention in the context of polymer composites. This article is therefore dedicated to understanding seeded polymerization from submicron sheets and focuses on the control of the overall morphology of the composite particles obtained. However, it was found that the composite particles only maintained the sheet-like morphology of the seeds at a low polymer content, whereas they became hamburger-like at a high polymer content owing to minimization of the interfacial energy. Interestingly, when cross-linked, the sheet-like morphology could be well preserved, even at a rather high polymer content. With the encapsulating polymer layer, the obtained sheet-like composite particles showed improved compatibility with the polymer matrix and could be well dispersed in polymer matrix when simply blended.
Co-reporter:Ting Huang;Chao Wang;Xinping Zhang;Chen Wang;Dr. Ailing Li;Dr. Dong Qiu
Chemistry – An Asian Journal 2015 Volume 10( Issue 3) pp:759-763
Publication Date(Web):
DOI:10.1002/asia.201403348
Abstract
A novel method was developed to synthesize organic–inorganic hybrid hollow sub-microspheres (HHSs) through the addition of colloidal SiO2. The hydrolysis rate of 3-(methacryloyloxy)propyltrimethoxysilane (MPS) was accelerated by SiO2 particles; meanwhile, the condensation rate of the hydrolytic species was decelerated. Thus, the hydrolytic monomers and oligomers of MPS were preserved as emulsifiers. These emulsifiers can then emulsify the isopentyl acetate (PEA) to form a steady O/W emulsion. The HHSs were produced by subsequent free radical polymerization and removal of the oil core. The hydrolytic MPS acted as emulsifiers and polymerizable monomers at the emulsification and polymerization stage, respectively. Thus, extra emulsifiers, co-emulsifiers, and organic monomers were omitted, which simplified the synthesis process. The good dispersion of HHSs in water and oil, as well as the EDX results, indicated the organic–inorganic hybrid structure of HHSs.
Co-reporter:Dao-hong Mei 邱东
Chinese Journal of Polymer Science 2015 Volume 33( Issue 12) pp:1691-1701
Publication Date(Web):2015 December
DOI:10.1007/s10118-015-1721-0
Using the continuum self-consistent field theory (SCFT), the adsorption of flexible symmetrical triblock polymers onto the surfaces of two identical parallel planes immersed in a neutral solution was studied. The effects of various parameters, such as the interface adhesive energy, the polymer composition and the bulk polymer concentration, on the conformations and total adsorption amount of polymers were explored. It was found that the dependence of the amount of bridges on the interface adhesion and that of the amount of tails on the length of adhesive blocks were both non-monotonous. The amounts of the four chain conformations scaled nearly linearly to the copolymer bulk concentration. The nonequivalence of the dependence of the adsorbed structure behaviors on the interface affinity and the length of sticky blocks was revealed as well.
Co-reporter:Zheng Yin;Jingjing Cao;Zhen Li
Environmental Science and Pollution Research 2015 Volume 22( Issue 13) pp:9668-9675
Publication Date(Web):2015/07/01
DOI:10.1007/s11356-015-4094-6
Dithiocarbamate chitosan (DTC-CTS) was used as a new amendment for remediation of cadmium (Cd)-contaminated soils to reduce the Cd bioavailability. Arabidopsis thaliana was chosen as a model plant to evaluate its efficiency. It was found that DTC-CTS could effectively improve the growth of A. thaliana. The amount of Cd up-taken by A. thaliana could be decreased by as much as 50 % compared with that grown in untreated Cd-contaminated soil samples. The chlorophyll content and the aerial biomass of Arabidopsis also increased substantially and eventually returned to a level comparable to plants grown in non-contaminated soils, with the addition of DTC-CTS. These findings suggested that DTC-CTS amendment could be effective in immobilizing Cd and mitigating its accumulation in plants grown in Cd-contaminated soils, with potential application as an in situ remediation of Cd-polluted soils.
Co-reporter:Chen Wang, Yue Xie, Ailing Li, Hong Shen, Decheng Wu, and Dong Qiu
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 7) pp:4935
Publication Date(Web):March 19, 2014
DOI:10.1021/am5014858
Bioactive nanoparticles with controllable size and good colloidal stability were synthesized through surface modification of colloidal silica nanoparticles with Ca(OH)2 as the modifier. These modified nanoparticles showed good bioactivity, showing evidence of hydroxyapatite formation when incubated in simulated body fluid within 3 days. Comparison of bioactivity was made among different sized particles from nanoscale to microscale. It was found the bioactivity of these calcium modified colloidal silica particles generally decreased with particle size in the explored size range (40 nm particles showed bioactivity within 1 day). These particles were also found to be noncytotoxic but promote preosteoblast growth, thus making them promising bioactive additives for bone repair materials.Keywords: Bioactive nanoparticle; bioactivity; Ca(OH)2; colloidal silica; surface modification;
Co-reporter:Chen Wang, Hong Shen, Ye Tian, Yue Xie, Ailing Li, Lijun Ji, Zhongwei Niu, Decheng Wu, and Dong Qiu
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 15) pp:13061
Publication Date(Web):July 21, 2014
DOI:10.1021/am5029582
Mechanical properties are among the most concerned issues for artificial bone grafting materials. The scaffolds used for bone grafts are either too brittle (glass) or too weak (polymer), and therefore composite scaffolds are naturally expected as the solution. However, despite the intensive studies on composite bone grafting materials, there still lacks a material that could be matched to the natural cancellous bones. In this study, nanosized bioactive particles (BP) with controllable size and good colloidal stability were used to composite with gelatin, forming macroporous scaffolds. It was found that the mechanical properties of obtained composite scaffolds, in terms of elastic modulus, compressive strength, and strain at failure, could match to that of natural cancellous bones. This is ascribed to the good distribution of particle in matrix and strong interaction between particle and gelatin. Furthermore, the incorporation of BPs endues the composite scaffolds with bioactivity, forming HA upon reacting with simulated body fluid (SBF) within days, thus stimulating preosteoblasts attachment, growth, and proliferation in these scaffolds. Together with their good mechanical properties, these composite scaffolds are promising artificial bone grating materials.Keywords: bioactive nanoparticle; cancellous bone; composite scaffold; gelatin; mechanical property
Co-reporter:Lei Ye, Xiao Chu, Zhengdong Zhang, Ying Kan, Yue Xie, Isabelle Grillo, Jiang Zhao, Cécile A. Dreiss and Dong Qiu
RSC Advances 2014 vol. 4(Issue 29) pp:14896-14903
Publication Date(Web):12 Mar 2014
DOI:10.1039/C4RA00929K
The effect of particle polydispersity on the structure and dynamics of small silica particle–large polymer chain mixtures at low polymer concentration has been investigated. Two types of silica particles were used as model systems, having similar mean size, specific surface area and surface properties but differing substantially in size polydispersity. Mixtures of PEO with the polydisperse silica particles showed strong shear-thickening upon shaking, while mixtures of the same composition with the monodisperse silica did not. Fluorescence correlation spectroscopy revealed that larger flocs were formed in the polydisperse particle–PEO systems. Particle polydispersity was identified as the major factor accounting for these differences and a plausible mechanism was proposed based on the spatial distribution of the silica particles within the complexes. This work suggests that the rheological behavior of colloid–polymer mixtures can be dramatically modified by a simple change in particle polydispersity, rather than more involved surface modifications or the use of additives.
Co-reporter:Xiaohui Meng, Xinping Zhang, Lei Ye, and Dong Qiu
Langmuir 2014 Volume 30(Issue 23) pp:7024-7029
Publication Date(Web):2017-2-22
DOI:10.1021/la501033f
Epoxy resin coated glass slides were used for colloidal particle lithography, in order to prepare well-defined 2D surface arrays. Upon the assistance of a large-sized 2D colloidal single crystal as template, centimeter-sized ordered surface arrays of bowl-like units were obtained. Systematic studies revealed that the parameters of obtained surface arrays could be readily controlled by some operational factors, such as temperature, epoxy resin layer thickness, and template particle size. With epoxy resin substituting for normal linear polymer, the height/diameter ratio of bowls in the formed surface arrays can be largely increased. With further reactive plasma etching, the parameters of ordered surface arrays could be finely tuned through controlling etching time. This study provides a facile way to prepare large-sized 2D surface arrays with tunable parameters.
Co-reporter:Yuan Wang, Weidong Qin, and Dong Qiu
Langmuir 2014 Volume 30(Issue 18) pp:5170-5175
Publication Date(Web):2017-2-22
DOI:10.1021/la501270k
The adsorptions of cyclic PEG and linear PEG on colloidal silica particles were compared. Their adsorption volume fraction profiles were generated through model fitting of small-angle neutron scattering data from the adsorbed polymer layers. The two important parameters to describe adsorbed polymer layers were discussed in detail. It was found that the adsorption amounts of cyclic PEGs increased with molecular weight but were generally higher than their linear counterparts. However, the root-mean-square layer thickness, δrms, of adsorbed cyclic PEGs was found to decrease with molecular weight, opposing adsorbed linear PEGs and the theoretic prediction based on SF model. This disagreement was ascribed to the topological restriction of cyclic polymer at low molecular weight. An illustrated structural evolution with molecular weight for adsorbed polymer at interface was tentatively proposed based on the observations of this study.
Co-reporter:Yinyan Guan, Xiaohui Meng, and Dong Qiu
Langmuir 2014 Volume 30(Issue 13) pp:3681-3686
Publication Date(Web):2017-2-22
DOI:10.1021/la404914g
Submicrometer hollow microspheres with mesoporous shells were prepared by a simple one-pot strategy. Colloidal silica particles were used as a particle stabilizer to emulsify the oil phase, which was composed of a polymerizable silicon monomer (TPM) and an inert organic solvent (PEA). The low interfacial tension between colloidal silica particles and TPM helped to form a Pickering emulsion with small droplet sizes. After the polymerization of TPM, the more hydrophobic PEA formed a liquid core, leading to a hollow structure after its removal by evaporation. BET results indicated that the shell of a hollow particle was mesoporous with a specific surface area over 400 m2·g–1. With PEA as the core and silica as the shell, each resultant hollow particle had a hydrophobic cavity and an amphiphilic surface, thus serving as a good colloidal collector for hydrophobic contaminants in water.
Co-reporter:Xiaohui Meng and Dong Qiu
Langmuir 2014 Volume 30(Issue 11) pp:3019-3023
Publication Date(Web):March 3, 2014
DOI:10.1021/la404944w
Centimeter-sized two-dimensional (2D) colloidal single crystals of polystyrene (PS) particles were fabricated at the water/air interface by capillary-modulated self-assembly. Different from previous reports, in this work, emulsifier was used to facilitate the stress release during 2D colloidal crystal formation by adjusting the interparticle lateral interactions. With the assistance of compressed nitrogen flow, 2D hexagonal colloidal single crystals of centimeter size were obtained under appropriate emulsifier concentrations. A new method was also developed to transfer the 2D colloidal crystals from the air/water interface to the desired substrate without obvious disturbance. This new transferring method was proven not to be sensitive to surface wettability nor curvature, thus 2D colloidal single crystals with large areas could be obtained on different kinds of substrate.
Co-reporter:Ting Huang and Dong Qiu
Langmuir 2014 Volume 30(Issue 1) pp:35-40
Publication Date(Web):2017-2-22
DOI:10.1021/la403284c
A sol–gel method was developed to prepare amorphous titanium dioxide (TiO2) submicrometer sheets (a-SMSs) with regular rhombic morphology without templates. These a-SMSs comprised of primary nanoparticles, which were organized in a close packing mode in a plane. Two-dimensional (2-D) directional self-assembly of primary nanoparticles was proposed as the mechanism of forming such regular a-SMSs. It was the first time to observe such regular SMSs in amorphous TiO2, which may lead to a new scenario for colloidal particle self-assembly. After calcination at 500 °C, the regular shape of a-SMSs was still maintained, while the a-SMSs turned into anatase submicrometer sheets (c-SMSs), which exhibited higher activity than commercial P25 in photodegradation of rhodamine B. Furthermore, due to their larger sizes, nearly 90% of c-SMSs were readily recovered after use by centrifugation at 2000 rpm, while hardly any P25 was recovered under a similar condition.
Co-reporter:Lei Ye, Yujing Tang, Dong Qiu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 447() pp:103-110
Publication Date(Web):5 April 2014
DOI:10.1016/j.colsurfa.2014.01.072
•Nanocomposite hydrogel with enhanced mechanical performance was prepared in situ.•Al-modified silica colloid significantly reinforces PAM hydrogel.•Aluminum was identified as the main reason for stronger PAM–silica interaction.Polyacrylamide (PAM)–silica nanocomposite hydrogels with enhanced mechanical performance were synthesized by in situ polymerization of acrylamide in the presence of colloidal silica nanoparticles. Two kinds of silica particle dispersions with different surface properties, CAL25 and 30R25, were used as models. The former is stabilized by aluminium while the latter by sodium. The compressive stress-strain measurements showed that CAL25 significantly enhanced the mechanical performance of PAM hydrogels while 30R25 only had marginal effect. This difference was attributed to different particle–polymer interactions and confirmed by adsorption behaviours of PAM on these two colloidal silica particles and rheological measurements, which suggested that CAL25 interacted much stronger with PAM. Aluminium was identified as the main reason contributing to stronger interactions between PAM and CAL25 particles.
Co-reporter:Lei Ye;Yue Xie 邱东;Ying Kan
Chinese Journal of Polymer Science 2014 Volume 32( Issue 11) pp:1515-1523
Publication Date(Web):2014 November
DOI:10.1007/s10118-014-1538-2
The effect of particle shape on the rheological behavior of small particle-large polymer chain mixture solutions has been investigated with two model colloidal silica dispersions, one of which is ellipsoidal (BINDZIL20/440) and the other is spherical (TM40). It was found that BINDZIL20/440 series showed shear-thickening at lower shear rates and had a lower upper limit in PEO concentration to demonstrate shear-thickening phenomena. The particle shape was identified as the major factor accounting for these differences. This work enables one to control the rheological behavior of colloid-polymer mixture through simply changing particle geometry instead of performing surface modifications, which could be especially useful in cases where only certain chemicals are allowed, for example in vivo applications.
Co-reporter:Kongli Xu, Guangming Chen and Dong Qiu
Journal of Materials Chemistry A 2013 vol. 1(Issue 40) pp:12395-12399
Publication Date(Web):23 Aug 2013
DOI:10.1039/C3TA12691A
A novel strategy via the convenient construction of a pie-like structure has been developed to prepare a poly(3,4-ethylenedioxythiophene)–reduced graphene oxide (PEDOT–rGO) nanocomposite with a greatly enhanced thermoelectric performance. Via a template-directed in situ polymerization, thick and uniform coatings of PEDOT layers were conveniently grown on both sides of the rGO nanosheet surfaces due to a strong π–π interfacial interaction. The nanocomposite exhibited a significantly enhanced thermoelectric performance at room temperature with a power factor of 5.2 ± 0.9 × 10−6 W m−1 K−2, greater than 13.3 times that of the PEDOT.
Co-reporter:Yi-Fan Huang, Ze-Ling Zhang, Kai-Bin Kang, Min Zhao, Ting Wen, Yun-Xia Liu, Xin-Ping Zhai, Shuang-Kun Lv, Qiang Wang, Wen-Yuan Qiu and Dong Qiu
RSC Advances 2013 vol. 3(Issue 36) pp:16080-16088
Publication Date(Web):04 Jul 2013
DOI:10.1039/C3RA43044H
Previous studies have concentrated on harnessing the surface plasmonic effects of metallic nanoparticles (NPs) to improve polymer solar cell performance. Although ample examples have evidenced the viability of this methodology, the adverse effect of device photocurrent reduction via the intrinsic metal-mediated losses of plasmonic metal NPs, which hampers further enhancement of device efficiency, has rarely been recognized. To address this issue, we herein embedded Au NPs coated with a dielectric SiO2 layer into polymer solar cells, attempting to reduce the negative effects of these metallic nanostructures and thus increase photovoltaic photocurrent and efficiency. We constructed inverted polymer solar cells based on poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester, and blended Au NPs coated with SiO2 layer, i.e. Au@SiO2 core–shell nanostructures into the active layer. Compared with plasmonic solar cells embedded with sole Au NPs, the device incorporating Au@SiO2 core–shell nanostructures indeed exhibited significantly augmented photocurrent density, though not a superior overall efficiency. The photocurrent density increase is attributed to the dielectric layer coating Au NPs, which mitigates metal-mediated losses such as exciton quenching, probably induced by the electron accumulation on the metallic surface, but which meanwhile is thin enough to maintain the plasmonic effects of the gold core upon photoexcitation. The study provides new insights into strategies harnessing plasmonic nanostructures to enhance photovoltaic performance, i.e. the balance between plasmonic effects and metal-mediated losses has to be comprehensively evaluated.
Co-reporter:Yong-Sen Sun, Ai-Ling Li, Fu-Jian Xu, Dong Qiu
Chinese Chemical Letters 2013 Volume 24(Issue 2) pp:170-172
Publication Date(Web):February 2013
DOI:10.1016/j.cclet.2013.01.009
Sol–gel-derived bioactive calcium silicates, synthesized from calcium nitrate tetrahydrate and calcium 2-methoxyethoxide as calcium precursor respectively, were calcified under different temperatures. A series of techniques including SEM, TGA, solid 29Si NMR, nitrogen adsorption, and simulated body fluids (SBF) soaking were employed to study their textural features and in vitro bioactivity. It was confirmed that calcium 2-methoxyethoxide is a promising candidate of calcium precursor for bioactive calcium silicates stabilized under low temperatures. This has implications in fabrication of organic–inorganic hybrid composites.A low-temperature sol–gel route combined with an ideal calcium precursor was created to prepare bioactive calcium silicates.
Co-reporter:Yi-Fan Huang, Kai-Hong Ma, Kai-Bin Kang, Min Zhao, Ze-Ling Zhang, Yun-Xia Liu, Ting Wen, Qiang Wang, Wen-Yuan Qiu, Dong Qiu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 Volume 421() pp:101-108
Publication Date(Web):20 March 2013
DOI:10.1016/j.colsurfa.2012.12.050
The accurate description of the energy and/or charge transfer mechanism involving Localized Surface Plasmon Resonance (LSPR) is crucial for the research field of plasmonics. The investigation is however frequently hampered by the inaccurate definition of separation distance between the energy and/or charge donor–acceptor pair. Herein we designed and constructed core–shell plasmonic nanostructures to realize precise, long separation distance control between the gold core (energy acceptor) and fluorophores (energy donor). Both steady-state and time-resolved fluorescence measurements were employed to investigate radiative properties of the as-prepared nanosystem. The observed overall fluorescence quenching of the core–shell plasmonic nanocomposites with the decrease of shell thickness is attributed to a concurrent increase of nonradiative rates and decrease of radiative rates with the separation distance decrease. However, neither fluorescence resonance energy transfer (FRET) nor nanometal surface energy transfer (NSET) model is suitable for describing the fluorescence quenching efficiency as a function of separation distance reported in this article. Remarkably, a long-range fluorescence quenching distance of over 34 nm is observed, possibly arising from the coincidence of fluorophore emission wavelength with the plasmon resonance of the gold nanoparticles. This study not only gains insight for designing novel plasmonic devices, but also provides new thoughts for investigation on molecular ruler on a larger measurement scale, molecular beacons and new generation photovoltaics.Highlights► Au@SiO2@FITC core–shell plasmonic nanostructures are designed and constructed. ► Precise, long separation distance control between Au core and FITC is realized. ► A long-range fluorescence quenching distance of over 34 nm is observed.
Co-reporter:Xiaohui Meng, Yinyan Guan, Zhongwei Niu, and Dong Qiu
Langmuir 2013 Volume 29(Issue 7) pp:2152-2158
Publication Date(Web):January 30, 2013
DOI:10.1021/la3045708
A facile method to prepare monodisperse speckled colloids has been developed via one-step seeded polymerization from noncross-linked latex particles. It was found that both cross-linking agents in the added monomer mixture and charged initiation species are essential for the formation of speckles on composite latex particle surface in seeded polymerization. The size and number density of speckles on the surface are tunable by adjusting the concentration of surfactant. A possible mechanism for the formation of such speckled colloids has been proposed based on a series of control experiments. Speckled colloidal particles were used as substrates for the adsorption of tobacco mosaic virus, and a much stronger adsorption was observed compared to smooth particles, implying a potential application of these speckled particles in virus collection and more.
Co-reporter:Li-Jian Qu, Xingkun Man, Charles C. Han, Dong Qiu, and Dadong Yan
The Journal of Physical Chemistry B 2012 Volume 116(Issue 2) pp:743-750
Publication Date(Web):December 14, 2011
DOI:10.1021/jp210165t
Self-consistent field theory (SCFT) calculation has been performed to study the structure and stimuli-responsive behaviors of diblock polyampholyte (PA) brushes. Two kinds of brushes are considered: one formed by PA chains consisting of two strong polyelectrolyte blocks (system i) and the other formed by PA chains of a grafted strong acid block and an ungrafted weak base block (system ii). Density profiles and brush thickness are obtained. The chain trajectory (average position of each polymer segment) is also calculated to characterize the conformation of the grafted chains. For system i, the ungrafted blocks loop backward at low salt concentration and extend out at high salt concentration. For system ii, the charge fraction of the annealing block is independent of pH and becomes dependent on it at high salt concentration. As a result, pH has no effect on the brush structure at low salt concentration and takes effect at high salt concentration. That the salt concentration can switch on and off the responses of the PA brush to the pH stimuli may find application in building functional surfaces.
Co-reporter:Xiaohui Meng, Yinyan Guan, Zhengdong Zhang, and Dong Qiu
Langmuir 2012 Volume 28(Issue 34) pp:12472-12478
Publication Date(Web):August 6, 2012
DOI:10.1021/la302392s
Core–shell particles with cross-linked core and shell were used as seed particles to produce composite Janus particles. It was found that when the shell has distinctly higher cross-linking degree than the core, Janus particles with very unusual structures can be obtained. These particles have two parts, with one part embraced partially or entirely by the other part, adjustable by parameters such as phase ratio or cross-linking degree. On the basis of experimental observations, a possible mechanism for the formation of such unusual Janus particles has been proposed. Janus particles with arms are used to emulsify water–toluene mixtures, forming oil-in-water (O/W) emulsions at very high internal phase content with rather low concentration of particles. Nonspherical emulsion droplets were observed, indicating that these Janus particles are likely to jam at the interface, forming a strong protecting layer to stabilize emulsions.
Co-reporter:Wenwu Li, Xingkun Man, Dong Qiu, Xinghua Zhang, Dadong Yan
Polymer 2012 Volume 53(Issue 15) pp:3409-3415
Publication Date(Web):6 July 2012
DOI:10.1016/j.polymer.2012.05.017
The role of weak adsorptive polymer chains in the colloidal particles solution is studied by self-consistent field theory (SCFT). The numerical results show the potential between colloids are attractive interaction. Besides the depletion effects the chain conformations such as loop, tail and bridge between two spherical colloidal particles play important roles. The quantitative polymer concentration dependent chain conformations and then the effective potential are also addressed.Graphical abstract
Co-reporter:Lijun Ji;Yunfeng Si;Ailing Li;Wenjun Wang
Frontiers of Chemical Science and Engineering 2012 Volume 6( Issue 4) pp:470-483
Publication Date(Web):2012 December
DOI:10.1007/s11705-012-1217-1
Bioactive glasses (BGs) are ideal materials for macroporous scaffolds due to their excellent osteoconductive, osteoinductive, biocompatible and biodegradable properties, and their high bone bonding rates. Macroporous scaffolds made from BGs are in high demand for bone regeneration because they can stimulate vascularized bone ingrowth and they enhance bonding between scaffolds and surrounding tissues. Engineering BG/biopolymers (BP) composites or hybrids may be a good way to prepare macroporous scaffolds with excellent properties. This paper summarizes the progress in the past few years in preparing three-dimensional macroporous BG and BG/BP scaffolds for bone regeneration. Since the brittleness of BGs is a major problem in developing macroporous scaffolds and this limits their use in load bearing applications, the mechanical properties of macroporous scaffolds are particularly emphasized in this review.
Co-reporter:Hui Liu ; Chaolong Li ; Dong Qiu ;Xiaofeng Tong
Journal of the American Chemical Society 2011 Volume 133(Issue 16) pp:6187-6193
Publication Date(Web):April 1, 2011
DOI:10.1021/ja201204g
A palladium-catalyzed iodine atom transfer cycloisomerization of (Z)-1-iodo-1,6-diene has been developed, which provides a facile method to construct six-memebered heterocycles bearing an alkyl iodide group. The ligand screening shows that both the type and the quantity of ligand impose significant influences on this transformation, and the combination of 30 mol % 1,1′-bis(diphenylphosphino)ferrocene (DPPF) and 10 mol % Pd(OAc)2 is the optimal choice. The catalytic cycle, consisting of oxidative addition of Pd(0) to vinyl iodide, intramolecular alkene insertion, and alkyl iodide reductive elimination, has been proposed and eventually supported by convincing evidence from a series of control experiments. More importantly, these control experiments disclose some features of the event of alkyl iodide reductive elimination: (1) this reductive elimination is proved to be a stereospecific process; and (2) both alkyl iodide oxidative addition and reductive elimination are not effected by a TEMPO additive. Besides its ability to undergo oxidative addition, the catalyst (palladium + DPPF) could also promote a radical transfer process. The findings described in this paper will be helpful for further development of the metal-catalyzed formation of a carbon−halide bond.
Co-reporter:Zewei Bai, Yue Xie, Chunhai Chen, Terence Cosgrove, Dong Qiu
Journal of Colloid and Interface Science 2011 Volume 358(Issue 1) pp:226-229
Publication Date(Web):1 June 2011
DOI:10.1016/j.jcis.2011.03.015
Dilute aqueous solutions of d-PEO and PSSNa mixtures were studied by 2H NMR spectroscopy and small-angle neutron scattering (SANS). The interactions between d-PEO and PSSNa were found to be negligible both in the presence and absence of NaCl. At very dilute concentration (0.7 mg mL−1), d-PEO chains were still found to be slightly collapsed at ambient temperature in water. Upon the addition of PSSNa, aggregates of d-PEO were observed with d-PEO coils loosely associated with each other. The average centre to centre distance between d-PEO coils, which was calculated from the maxima in SANS spectra, was similar to the size of the individual coils. The effect of a simple salt, NaCl, on d-PEO-PSSNa interaction was investigated. Salt addition induced a breakdown of the dilute d-PEO aggregates.Graphical abstractDepletion interactions owing to non-interacting PSSNa assist the formation of dilute PEO aggregates, which break down upon adding simple screening salt.Highlights► PEO molecules form Gaussian chains in dilute aqueous solutions at ambient temperature. ► With added PSSNa depletion interactions assist the formation of dilute PEO aggregates. ► These dilute PEO aggregates break down upon adding simple screening salt.
Co-reporter:A. Li, D. Wang, J. Xiang, R.J. Newport, M.X. Reinholdt, P.H. Mutin, D. Vantelon, C. Bonhomme, M.E. Smith, D. Laurencin, D. Qiu
Journal of Non-Crystalline Solids 2011 Volume 357(19–20) pp:3548-3555
Publication Date(Web):October 2011
DOI:10.1016/j.jnoncrysol.2011.07.003
Amorphous calcium phosphosilicate xerogels of high phosphate content were synthesized by a new sol–gel route. Their structural characterization was achieved through the combination of complementary analytical methods, including advanced solid state NMR and scattering techniques. Two representative compositions, with similar P contents but a different Ca:Si ratio, have been chosen for detailed study. Using 43Ca solid state NMR and Ca K-edge XANES, the Ca local environment in the samples was characterized, revealing that it is similar for both compositions. It was found that POSi linkages are present in both compounds after calcination at 350 °C. However, for the sample with the lower Si content, a higher fraction of unusual 6-coordinated silicon was observed. Interestingly, calcium was also found to enhance the network connectivity and to enter the phosphosilicate network without the need for calcination at high temperature, which is advantageous in comparison with syntheses performed previously on similar compounds.Highlights► Calcium cations enter gel network at low temperature with the help of phytic acid. ► Calcium cations are mainly located in the vicinity of phosphate tetrahedron. ► Gel network is highly crosslinked between phosphate and silicate. ► Calcium enhances the overall network connectivity. ► High coordinated silicon at high phosphate content.
Co-reporter:Ailing Li
Journal of Materials Science: Materials in Medicine 2011 Volume 22( Issue 12) pp:2685-2691
Publication Date(Web):2011 December
DOI:10.1007/s10856-011-4464-7
The possibility of using phytic acid as a precursor to synthesize CaO–P2O5–SiO2 glasses by sol–gel method has been explored and the pseudo ternary phase diagram has been established. It was shown that gel-glasses over a broader range of compositions could be prepared compared to other phosphorus precursors or melt-quenching method. Furthermore, phytic acid was found to assist calcium being incorporated into glass networks. In vitro tests in simulated body fluid (SBF) were performed on the above gel–glasses and it was found that they were bioactive over a much broader compositional range especially at high phosphate content, thus enabling one to design bioactive materials with various degradation rates by adjusting the phosphate content.
Co-reporter:Tao Zhao and Dong Qiu
Langmuir 2011 Volume 27(Issue 21) pp:12771-12774
Publication Date(Web):October 3, 2011
DOI:10.1021/la2028912
A facile method of preparing highly folded cross-linked polymeric microparticles has been developed via one-pot suspension polymerization under high-speed homogenization. The wrinkles result from the evaporation of solvent in the cross-linked microparticles. The effects of microparticle cross-linking density and solvent on the polymer have been studied in detail. It was found that a medium cross-linking density (DVB/St = 0.5 by weight) is optimal for producing the most folded surface and the higher the solvent content, the deeper the surface wrinkles. This method is very simple and in principle can be applied to produce wrinkled microparticles with other chemical compositions.
Co-reporter:Dong Qiu, Richard A. Martin, Jonathan C. Knowles, Mark E. Smith, Robert J. Newport
Journal of Non-Crystalline Solids 2010 Volume 356(9–10) pp:490-494
Publication Date(Web):15 March 2010
DOI:10.1016/j.jnoncrysol.2009.12.016
The atomic scale structure of sodium borophosphates made by the sol–gel method is compared to those made by the melt-quench method. It is found that although the sol–gel generated materials have a higher tendency towards crystallization, they nevertheless show a qualitatively similar crystallization trend with composition to their melt-quench analogues; the progressive introduction of boron oxide into the phosphate network initially inhibits then promotes crystallization. At the composition associated with the most stable amorphous sodium borophosphate (20 mol% boron oxide), it is found that the atomic scale structure of the sol–gel synthesized network glass is almost identical to that of the corresponding melt-quenched one.
Co-reporter:Lijun Ji, Wei Qiao, Kai Huang, Yuheng Zhang, Huayu Wu, Shiyong Miao, Hongfei Liu, Yixiang Dong, Aiping Zhu, Dong Qiu
Materials Science and Engineering: C (1 June 2017) Volume 75() pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.msec.2017.02.107
•Nanosized 58S BG particles were prepared by using a MOC template.•The 58S particles possessed narrow size distribution and spherical morphology.•The narrow size distribution was confirmed crucial to gelatin composite.•The mechanical properties of the gelatin composite were improved significantly.•The outstanding bioactivity of the 58S BG particles was confirmed.Nanosized 58S bioactive glass (BG) particles were synthesized by using a three-dimensional ordered macroporous carbon template (OMC) with a pore size of 400 nm. The obtained 58S BG particles possessed a diameter of 300 nm, narrow size distribution and uniform spherical morphology. 58S/gelatin composites were prepared and showed much better mechanical properties than pure gelatin. The narrow size distribution of the 58S particles replicated from OMC was confirmed crucial to the mechanical properties of the 58S/gelatin composite, comparing to the contrast sample prepared with polydispersed particles. The outstanding bioactivity of the 58S BG particles was confirmed by inducing the formation of carbonated hydroxyapatite on the 58S/gelatin composite surface. This work showed a successful example that OMC template could be used to synthesize particles requiring a robust reaction condition, and a particle synthesis method that could well control particle size distribution was important for preparing materials with outstanding mechanical properties.
Co-reporter:Feiyan Zhu, Chen Wang, Saina Yang, Qian Wang, Fuxin Liang, Chenyang Liu, Dong Qiu, Xiaozhong Qu, Zhongbo Hu and Zhenzhong Yang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 13) pp:NaN2424-2424
Publication Date(Web):2017/03/01
DOI:10.1039/C7TB00384F
In this work, an injectable composite hydrogel was synthesized via a unique way of crosslinking glycol chitosan (GC) with silica nano-particles (SiNP) through non-chemical interactions, and was then applied as a kind of wound dressing. Gelation was achieved through the incorporation of SiNPs with the GC segments in aqueous solution, therefore strictly confining the movement of the solubilized polymer chains. Rheology tests showed that the sol–gel transition and the moduli of the hydrogel were influenced by the composition of the two components, the size of the nano-particles and the conformation of the polymers. Using such a strategy, tissue adhesion properties of GC were well-preserved in the GC/SiNP hydrogel and therefore it gains gluey properties toward biological tissues as demonstrated through the adhesion of two pieces of mouse skin, obtaining a lap-shear stretching force of ca. 90 kPa. This characteristic, together with the injectability, allowed the hydrogel to be administrated directly on the wound site and to fill the wound area. Meanwhile, the hydrogel also works as a carrier of protein and cells. The in situ encapsulation of fibroblasts enabled the promising properties of the GC/SiNP hydrogel to be used for treating full-thickness skin defects in a mouse model, resulting in the favorable growth of hair follicles and microvessels, hence reducing the risk of scar formation.
Co-reporter:Runrun Wu, Jianming Pan, Xiaohui Dai, Dong Qiu, Hengjia Zhu, Yue Ma, Weidong Shi and Yongsheng Yan
Chemical Communications 2015 - vol. 51(Issue 90) pp:NaN16254-16254
Publication Date(Web):2015/09/14
DOI:10.1039/C5CC06516J
Herein, we propose a facile protocol for the fabrication of biomedical microstructures with fine textures of hierarchical rippled and crumpled morphologies through double emulsions by the simple addition of interior Pickering nanoparticles.
Co-reporter:Kongli Xu, Guangming Chen and Dong Qiu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 40) pp:NaN12399-12399
Publication Date(Web):2013/08/23
DOI:10.1039/C3TA12691A
A novel strategy via the convenient construction of a pie-like structure has been developed to prepare a poly(3,4-ethylenedioxythiophene)–reduced graphene oxide (PEDOT–rGO) nanocomposite with a greatly enhanced thermoelectric performance. Via a template-directed in situ polymerization, thick and uniform coatings of PEDOT layers were conveniently grown on both sides of the rGO nanosheet surfaces due to a strong π–π interfacial interaction. The nanocomposite exhibited a significantly enhanced thermoelectric performance at room temperature with a power factor of 5.2 ± 0.9 × 10−6 W m−1 K−2, greater than 13.3 times that of the PEDOT.
Co-reporter:Ailing Li, Hong Shen, Huihui Ren, Chen Wang, Decheng Wu, Richard A. Martin and Dong Qiu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 7) pp:NaN1390-1390
Publication Date(Web):2014/12/22
DOI:10.1039/C4TB01776E
New sol–gel functionalized poly-ethylene glycol (PEGM)/SiO2–CaO hybrids were prepared with interpenetrating networks of silica and PEGM through the formation of Si–O–Si bonds. Bioactive and mechanical properties were investigated for a series of hybrids containing varying organic/inorganic ratios and PEG molecular weights. In contrast to the unmodified PEG/SiO2–CaO hybrids, which rapidly dissolved and crumbled, the epoxy modified hybrids exhibited good mechanical properties and bioactivity. The compressive strength and Young's modulus were greater for higher molecular weight PEGM hybrids (PEGM600 compared to PEGM300). Compressive strengths of 138 MPa and 81 MPa were found for the 50:50 and 60:40 organic/inorganic hybrid samples respectively, which are comparable with cortical bone. Young's modulus values of ∼800 MPa were obtained for the 50:50 and 60:40 organic/inorganic hybrids. Bioactivity tests were conducted by immersing the hybrids into simulated body fluid and observing the formation of apatite. Apatite formation was observed within 24 hours of immersion. PEGM600 hybrids showed enhanced apatite formation compared to PEGM300 hybrids. Increased apatite formation was observed with increasing organic/inorganic ratio. 70:30 and 60:40 hybrids exhibited the greatest apatite formation. All PEGM hybrids samples had good cell viability and proliferation. The 60:40 PEGM600 hybrids displayed the optimal combination of bioactivity and mechanical strength. The bioactivity of these hybrids, combined with the enhanced mechanical properties, demonstrate that these materials have significant potential for bone regeneration applications.
![Gadolinate(1-),[1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetato(4-)-kN1,kN4,kN7,kN10,kO1,kO4,kO7,kO10]-, sodium (9CI)](http://img.cochemist.com/ccimg/93000/92923-44-9.png)
![Gadolinate(1-),[1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetato(4-)-kN1,kN4,kN7,kN10,kO1,kO4,kO7,kO10]-, sodium (9CI)](http://img.cochemist.com/ccimg/93000/92923-44-9_b.png)
![2-Propenoic acid, 2-methyl-, 2-(3',3'-dimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-[2H]indol]-1'(3'H)-yl)ethyl ester](/data/chemimg/3778900/25952-50-5.png)
![2-Propenoic acid, 2-methyl-, 2-(3',3'-dimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-[2H]indol]-1'(3'H)-yl)ethyl ester](/data/chemimg/3778900/25952-50-5_b.png)
