Co-reporter:Tianfu Zhang;Zhuang Ma;Guoping Li
RSC Advances (2011-Present) 2017 vol. 7(Issue 2) pp:904-913
Publication Date(Web):2017/01/03
DOI:10.1039/C6RA24857H
Since the thermite reaction in aluminum-based nanostructured energetic materials (NEMs) is closely involved with Al and oxide nanoparticles (NPs), intimate interfacial contact between the Al and oxide NPs is widely considered to be a key parameter for the NEMs with high reactivity. With the aim to overcome the disadvantage of inert modifiers without energetic groups, used in the assembly approach, which is a cutting-edge solution to precisely organize the arrangement of the Al and oxide NPs and lead to enhanced intimacy, we successfully prepared GAP-based (GAP, glycidyl azide polymer) energetic polyelectrolytes (GEPEs) and demonstrated electrostatic assembly as a facile way to fabricate high performance, reactive Al/Fe2O3 microspheres after modification of the Al and Fe2O3 NPs with the GEPEs. The pressurization rate of the obtained reactive microspheres, a relative measurement of the reactivity, reached 410.36 MPa s−1, which is the highest value obtained so far, and is 1–2 orders of magnitude higher than that of other reported Al/Fe2O3 NEMs. The incorporated GEPEs serve three main roles: GEPEs act as a modifier by interacting strongly with the NPs, and improve the intimacy of the Al and Fe2O3 via powerful electrostatic attraction between the modified NPs; the assembly of the reactive microspheres can be achieved through the directing assembly of the GEPEs themselves; internal gas released by the decomposition of energetic sites existing inside the assembled microspheres rapidly separates the NPs to prevent adverse sintering and to weaken the nanostructure loss during the reaction, resulting in an improvement of the reactivity.
Co-reporter:Yanguang Wu;Zhuangcheng Yi
Journal of Thermal Analysis and Calorimetry 2017 Volume 129( Issue 3) pp:1555-1562
Publication Date(Web):11 April 2017
DOI:10.1007/s10973-017-6387-0
Glycidyl azide polymer (GAP) is a promising candidate for energetic binders in future solid propellants with minimum smoke signature, reduced pollution and low sensitivity. A series of GAP-modified nitrocellulose (NC) spherical powders were prepared by an internal solution method, and its properties have been studied. SEM characterization showed that the GAP-modified NC spherical powders exhibited high roundness rate, excellent fluidity and the favorable uniformity of its corresponding propellant. XRD analyses and DSC test indicated that GAP and NC molecular chain segment had a certain degree of compatibility, and GAP molecular had desirable plasticizing effect on NC. TG–FTIR–MS coupled method revealed that GAP-modified NC spherical powders had three decomposition stages, corresponding to the decompositions of O–NO2 groups, –N3 groups and the main chains of NC and GAP, respectively. The onset decomposition temperature of GAP-modified NC spherical powders was 5.67 °C higher than that of pure NC spherical powders, which was very important for its safety performance. The NO2, CO2 and NO were detected from the gas products of first decomposition stage, while CO, H2CO2, CH4, HCN and NH3 were identified from the gas products of second decomposition stage. Finally, CO and CO2 were produced from the third decomposition stage. The thermal decomposition process of GAP-modified NC spherical powders was presented.
Co-reporter:Yuanfei Lan;Jingke Deng;Guoping Li
Journal of Thermal Analysis and Calorimetry 2017 Volume 127( Issue 3) pp:2173-2179
Publication Date(Web):15 September 2016
DOI:10.1007/s10973-016-5838-3
The graphene/Fe2O3 nanocomposites were prepared by the sol–gel method and then dried naturally in air or supercritical CO2. X-ray diffraction, scanning electron microscopy and specific surface area analysis were used to characterize the structure of the nanocomposites. The nanocomposites dried with supercritical CO2 have larger specific area and porous structure. The catalytic properties of the graphene/Fe2O3 nanocomposites for ammonium perchlorate were investigated by differential scanning calorimetry. When the nanocomposites were added, not only the thermal decomposition temperature of ammonium perchlorate was decreased, but also the exothermic heat was increased. Comparing the two drying methods, the graphene/Fe2O3 nanocomposites dried with supercritical CO2 showed better catalytic effects.
Co-reporter:Xuan Yin;Chenghao Dong
Colloid and Polymer Science 2017 Volume 295( Issue 12) pp:2423-2431
Publication Date(Web):31 October 2017
DOI:10.1007/s00396-017-4218-2
A novel hydrophilic curing agent was prepared through hexamethylene diisocyanate trimer, polyethylene glycol monomethyl ether, and 2-((2-aminoethyl)amino)-ethanesulfonic acid monosodium salt. Then, flame-retardant two-component waterborne polyurethanes and their coatings were synthesized through adding the novel hydrophilic curing agent. Their properties and analysis were characterized through fourier-transformed infrared spectroscopy, differential scanning calorimeter, thermogravimetric, thermogravimetric infrared, limiting oxygen index, and UL-94. As a result, the −NCO content of novel hydrophilic curing agent was 16.4% and above 10.0% about 4 months. Besides, the novel hydrophilic curing agent dispersed well in two-component emulsions and improved themostability and compatibility of two-component flame-retardant waterborne polyurethanes. Meanwhile, the tensile strength of the novel film was 1.5 times than the previous one through adding novel hydrophilic curing agent at the same stoichiometric ratio of −NCO to −OH. What’s more, the best LOI and UL-94 of modified flame-retardant two-component waterborne polyurethane were 29.2% and V-0, respectively.
Co-reporter:Xuan Yin, Yunjun LuoJing Zhang
Industrial & Engineering Chemistry Research 2017 Volume 56(Issue 7) pp:
Publication Date(Web):January 27, 2017
DOI:10.1021/acs.iecr.6b04452
Diethyl N,N-bis(2-hydroxyethyl)aminomethylphosphonate and halogen-free poly(phosphate) as reactive halogen-free flame retardants and soft or hard segment modifiers were compounded to waterborne polyurethane polyols after being emulsified and then were mixed with isophorone diisocyanate and dimethylolpropionic acid to synthesize two-component waterborne polyurethanes having fire resistance. As a result, the rheological behavior of prepolymer emulsion really accords with characteristics of non-Newtonian fluid. The highest limit oxygen index is 27.8% in two-component system modified by hard segment, which was 527.5% than the clean; meanwhile, one is 28.6% in another two-component system, which was 627.6% than the clean. The hardness, solvent resistance, and mechanical property in both of the two-component systems are outstanding. Adding flame retardant can effectively improve the flame resistance, tensile strength, and pot-life of two-component waterborne polyurethanes, especially in being modified by soft segment.
Co-reporter:Yajin Li;Song Ma;Jingke Deng
Colloid and Polymer Science 2017 Volume 295( Issue 4) pp:637-646
Publication Date(Web):2017 April
DOI:10.1007/s00396-017-4050-8
A series of glycidyl azide polymer (GAP) with hydroxyl-terminated poly(ethylene oxide-co-tetrahydrofuran) (P(EO-co-THF)) polymer networks of various functional molar ratios (R) and different GAP contents have been prepared through the step-wise curing process. The step-wise curing condition is determined based on the thermodynamic parameters of each simplex elastomer system, which is 45 °C-3d then 60 °C-4d. The mechanical properties of the elastomers have been improved from 1.88 to 2.11 MPa in WGAP = 50% under that condition, which is caused by the formation of the larger-sized mesh structure and in consequence the effective elastic strands increase. Meanwhile, the dynamic mechanical analysis (DMA) reveals that the glass transition temperatures of the elastomers are approximately −62.42 and −26.96 °C, respectively. Moreover, it can be concluded through DMA that the P(EO-co-THF) domains act as the main crosslinking joints compared with the GAP/N100 domains and thus cause the constrained effect. Combining extension test with DMA results, the network model of the elastomers is depicted. In addition, the thermal stabilities of the blending elastomers have also been studied, and their thermal stabilities meet the requirements of military materials.
Co-reporter:B. J. Li;Y. J. Luo;J. Zheng
Polymer Science, Series A 2017 Volume 59( Issue 3) pp:301-309
Publication Date(Web):10 March 2017
DOI:10.1134/S0965545X17030117
Various molecular weight of poly(3,3-bis(azidomethyl)oxetane) were prepared from 3,3-bis(chloromethyl) oxetane. The structure of those were confirmed by Fourier transform infrared, proton nuclear magnetic resonance spectral analysis and gel permeation chromatograph, meanwhile the properties were also compared by X-ray diffraction, differential scanning calorimetry and rheological analysis. The results indicated that increasing molecular weight weakened the crystallization ability of PBAMO and increased the glass transition temperature. Furthermore, the viscosity, shear stress, G′ and G″ of PBAMO increased gradually with increasing of the molecular weight.
Co-reporter:Ze-Huan Hei, Mu-Hua Huang, Yunjun Luo and Yingxiong Wang
Polymer Chemistry 2016 vol. 7(Issue 4) pp:770-774
Publication Date(Web):24 Nov 2015
DOI:10.1039/C5PY01682G
A well-defined nitro group functionalized porous aromatic framework (NO2-PAF-1) was synthesized via a bottom-up strategy using a copper-mediated Ullmann reaction. The synthetic route is cost-efficient and robust for large scale preparation. The Brunauer–Emmett–Teller (BET) specific surface area of the obtained NO2-PAF-1 is up to 610 cm2 g−1 with micro/mesoporosity. Its CO2 uptake was measured to be higher than that of PAF-1 due to the strong interaction between the nitro groups and CO2 molecules, proven by the enhanced isosteric heat of CO2 adsorption (38.4 kJ mol−1).
Co-reporter:Abbas Tanver, Fida Rehman, Aisha Wazir, Syed Khalid, Song Ma, Xiaoyu Li, Yunjun Luo and Mu-Hua Huang
RSC Advances 2016 vol. 6(Issue 13) pp:11032-11039
Publication Date(Web):08 Jan 2016
DOI:10.1039/C5RA23250C
To improve the thermo-mechanical properties of glycidyl azide polymer (GAP) and hydroxyl terminated polybutadiene (HTPB) based propellants, a facile sequential polymerization approach has been conducted to prepare an energetic hybrid polymer network (EHPN) through stepwise curation. The detailed curing conditions for the EHPN formation were determined using an in situ FTIR kinetic study. The effect of curing ratio (NCO/OH) on the mechanical properties of the polyurethane networks of GAP and HTPB was investigated, wherein hexamethylene diisocyanate biuret trimer (Desmodur N100) and isophorone diisocyanate (IPDI) were used as mixed curative agents. A series of EHPNs were prepared by varying the relative weight ratios of GAP and HTPB with a single poly-isocyanate mixed curing system (IPDI/N100). A remarkable mechanical strength of up to 5.83 MPa and an elongation at break of 359% were achieved with a 50:50 weight ratio of GAP to HTPB, which is the maximum mechanical strength reported thus far for a binder system of GAP and HTPB, which has a thermally more stable cross-linked network. The thermal properties of the as-synthesized PU networks of GAP, HTPB and GAP–HTPB EHPNs with different weight ratios were characterized using the DMA and DSC techniques. Thermal degradation behavior and morphological studies were also investigated with TGA-DTG and scanning electron microscopy (SEM), respectively. The facile sequential polyurethane curation polymerization technique can be potentially used for advanced solid composite propellants.
Co-reporter:Gang Wu, Jinqing Li, Yunjun Luo
Polymer Degradation and Stability 2016 Volume 123() pp:36-46
Publication Date(Web):January 2016
DOI:10.1016/j.polymdegradstab.2015.11.004
A series of novel flame-retardant waterborne polyurethanes (AWPUs) with a phosphorus-containing flame retardant diamine (Bis (4-aminophenoxy) phenyl phosphine oxide (BPPO)) were synthesized by the method of post-chain extension technique and the structure was confirmed by FTIR and NMR. The phosphorus-containing chain extender improved the tensile strength but decreased the elongation at break. Influences of BPPO on the thermal degradation properties and flame retardancy of AWPU's were investigated by thermal gravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter test (CCT). TGA results showed that the post-chain extension of BPPO promoted the degradation process and reduced the thermal stability of AWPUs. LOI, UL-94 and CCT indicated that the flame retardancy was improved with the increase of BPPO. When the chain extension ratio reached 100%, the LOI increased up to 30.1%, PHRR and THR were reduced by 57.1% and 41.6% respectively. The thermal degradation mechanism of AWPUs with chain extension of BPPO was studied by several measurements such as TGA-FTIR, in situ FTIR, SEM and EDS analysis, the results showed that the decomposition of AWPUs were divided into three stages. First of all, BPPO decomposed, and then the degradation of hard segment of AWPUs took place followed by the degradation of soft segment of AWPUs.
Co-reporter:Jingjing Feng, Zhen Ge, Chunpeng Chai, Shengpeng Wang, Dehai Yu, Gang Wu, Yunjun Luo
Progress in Organic Coatings 2016 Volume 97() pp:91-98
Publication Date(Web):August 2016
DOI:10.1016/j.porgcoat.2016.03.020
•A novel bifunctional waterborne polyurethane with both flame retardancy and hydrostatic pressure resistance was synthesized.•TGA and TGA-FTIR-MS revealed that the ExolitOP550 can catalyze the formation of a protective char layer and release new nonflammable gas.•The coated textiles showed excellent hydrostatic pressure resistance performance and the flame retardant property compared with the uncoated counterparts.In this work, a series of flame retardant modification crosslinking waterborne polyurethanes (OWPUs) were synthesized. The structures, emulsion performance, film and application properties of prepared OWPUs were investigated. Conclusions drawn from the study were that the incorporation of flame retardant ExolitOP550 makes the particle size of the OWPU dispersions larger, and the result of Zeta potential can be deduced that all polyurethane dispersions are well stabilized. Thermogravimetric analysis (TGA) and thermogravimetric analysis-fourier transform infrared spectroscopy-mass spectrometry (TGA-FTIR-MS) revealed that the ExolitOP550 can catalyze the formation of a protective char layer and release new nonflammable gas. Hence, as the content of ExolitOP550 increases, the limiting oxygen index (LOI) of OWPU films and the flame resistance of OWPU fabric specimens become better and better. After coated, textiles showed excellent hydrostatic pressure resistance performance and the flame retardant property compared with the uncoated counterparts. However, the hydrostatic pressure decreased with the increase of ExolitOP550. In view of the comprehensive performance of OWPUs, especially the application properties, well performed OWPU may be synthesized with 12 wt% proportion of ExolitOP550.
Co-reporter:Jingke Deng;Guoping Li;Min Xia;Yuanfei Lan
Journal of Applied Polymer Science 2016 Volume 133( Issue 35) pp:
Publication Date(Web):
DOI:10.1002/app.43840
ABSTRACT
Two kinds of flexible chain polymer, poly(ethylene oxide-co-tetrahydrofuran) (P(EO-co-THF)) and polyalkylene oxide (PAO), were chosen to improve the mechanical properties of the network of glycidyl azide polymer (GAP)–based elastomers. The mechanical properties of the GAP binder system at 25 and −40 °C can be improved effectively. The effects of P(EO-co-THF) and PAO on the network parameters, hydrogen bonding effect, and crystallization property were studied to determine the enhancement mechanism. Based on the results, it can be concluded that for copolyurethane elastomers prepared with PAO content less than 15 wt % and P(EO-co-THF), the mechanical properties were enhanced by the reduction of bulk side groups in GAP, which improved the chemical crosslinking density, hydrogen bonding effect in elastomers, and the motility of the molecular chains, while for elastomers prepared with more than 15 wt % PAO, the crystallization of the PAO segments played a major role in the improvement of mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43840.
Co-reporter:Benbo Zhao;Tianfu Zhang;Zhen Ge
Science China Chemistry 2016 Volume 59( Issue 4) pp:472-477
Publication Date(Web):2016 April
DOI:10.1007/s11426-015-5538-z
Glycidyl azide polymer (GAP) with the advantages of non-volatility and excellent thermal stability is a candidate as a replacement for nitroglycerine (NG) in a double base propellant. The GAP-NC double base propellants were formulated with GAP and nitrocellulose (NC) fibers. Tensile test and SEM characterization indicated that GAP-NC propellants had a homogeneous structure. Thermogravimetric analysis of GAP-NC propellants revealed that the onset decomposition temperature reached a high level ranging from 192.9 to 194.6 °C, which indicated that the substitution of NG with GAP contributed to the safe storage and process operations for double base propellant. The result analysis of decomposition products of GAP-NC propellants showed that the main gas decomposition products of the propellants were NO, NO2, CO, CO2, NH3, CH4, HCN, N2, CH2O and C2H4O. The thermal decomposition process of the specimens was proposed.
Co-reporter:Limin Gu;Chunpeng Chai
Journal of Polymer Research 2016 Volume 23( Issue 4) pp:
Publication Date(Web):2016 April
DOI:10.1007/s10965-016-0954-0
Three phosphorus-nitrogen content effective synergist flame-retardant water-borne coatings have been synthesized, and their structures were characterized by infrared spectroscopy. Cotton and polyester fabrics have been treated by coatings to improve their flame retardancy. The thermal performances and flame retardant properties of treated samples were investigated by thermogravimetric analysis (TGA), horizontal flame test, vertical burning test, limiting oxygen index (LOI), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), respectively. The combustion performances of cotton and polyester fabrics have proven to be strongly affected by flame-retardant coatings and HFD-coating performed the best. As a result, the LOI value of treated cotton increased to 22.5, and the UL-94 value of treated polyester achieved V-0. In addition, the antistatic behavior, hydrostatic pressure, tearing strength and wrinkle recovery angle of samples were studied carefully, and the results showed that all of these performances were improved.
Co-reporter:Zhen Wang;Tianfu Zhang;Zaijuan Zhang;Zhen Ge
Polymer Bulletin 2016 Volume 73( Issue 11) pp:3095-3104
Publication Date(Web):2016 November
DOI:10.1007/s00289-016-1643-1
A series of glycidyl azide polyol (GAP)-based ETPEs with different hard-segment contents were synthesized using GAP-diol, hexamethylene diisocyanate and 1, 4-butanediol as soft and hard segments, respectively, by prepolymerization. The synthesized GAP-based ETPEs were identified and characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and rheometric spectrometry. The results of FTIR showed the forming of carbonyl hydrogen bonds in ETPEs was affected by hard-segment contents of ETPEs. DSC results showed that the glass transition temperature (Tg) of ETPEs was also affected by the percentage of hard-segment contents of ETPEs. It was shown by DMA and rheological measurements that the percentage of hard-segment contents of ETPE had a monotonic effect on the rheological properties of ETPEs.
Co-reporter:Song Ma;Yajin Li;Yang Li
Journal of Molecular Modeling 2016 Volume 22( Issue 2) pp:
Publication Date(Web):2016 February
DOI:10.1007/s00894-016-2913-4
To improve the practicality and safety of a novel explosive dihydroxylamm onium 5,5′-bis (tetrazole)-1,1′-diolate (TKX-50), polyvinylidene difluoride (PVDF) and polychlorotrifluoroe-thylene (PCTFE) were respectively added to the TKX-50, forming the polymer-bonded explosives (PBX). Interfacial and mechanical properties of PBX were investigated through molecular dynamics (MD) method, desensitizing mechanisms of fluorine-polymers for TKX-50 were researched by compression and bulk shear simulations. Results show that the binding energies (Ebind) between polymers (PVDF or PCTFE) and TKX-50 surfaces all rank in order of (011) > (100) > (010), shorter interatomic distance and the resulted higher potentials lead to higher Ebind on TKX-50/PVDF interfaces than that on PCTFE/TKX-50 interfaces. Compared with TKX-50, the ductility of PBX is improved due to the isotropic mechanical property and flexibility of fluorine-polymers especially the PCTFE. Desensitizing effect of fluorine-polymers for TKX-50 is found under loading condition, which is attributed to the enhanced compressibility and buffer capacity against external pressure in compression, as well as the improved lubricity to reduce the sliding potentials in bulk shear process.
Co-reporter:Yanguang Wu;Zhen Ge
Journal of Thermal Analysis and Calorimetry 2016 Volume 124( Issue 1) pp:107-115
Publication Date(Web):2016 April
DOI:10.1007/s10973-015-5122-y
GAP modified double-base powder was prepared by an internal solution method and applied in cross-linked modified double-base propellants. It was found that if GAP content was not more than 30 %, the modified double-base powders had high roundness rate, no bonding between the particles and excellent fluidity. The median diameter (d50) of powders was decreased from 90.24 to 72.41 μm when the amount of GAP increased from 0.0 to 30.0 %. The thermal decomposition peak temperatures of –N3 and GAP’s main chain were found to be lower for the 10.0, 20.0 and 30.0 % GAP modified powders than the corresponding peak temperatures for pure GAP. The drop mass impact sensitivity of the modified powders is reduced as the mass ratio of GAP increases. It was experimentally shown that GAP modified double-base powders can improve the mechanical characteristics of the propellant with a maximum tensile strength (σm) between 0.45 MPa < σm < 1.18 MPa and an elongation at maximum tensile strength (εm) between 29.80 % < εm < 52.60 % at temperatures of −40, +20 and +50 °C.
Co-reporter:YUANFEI LAN;XUEBAO WANG
Bulletin of Materials Science 2016 Volume 39( Issue 7) pp:1701-1707
Publication Date(Web):2016 December
DOI:10.1007/s12034-016-1320-x
Graphene aerogel (GA) with nano-porous structure was assembled through the formation of physical cross-links between graphene sheets by a facile sol–gel method and supercritical CO2 drying process. Then hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was added and trapped in the nano-porous three-dimensional networks of GA to obtain a novel GA/RDX nanostructured energetic composite. The composition, morphology and structure of the obtained GA/RDX nanostructured energetic composite were characterized by elemental analysis, scanning electron microscopy, nitrogen sorption tests and X-ray diffraction. Moreover, the thermal decomposition characteristic was investigated by thermogravimetry and differential scanning calorimetry. The results showed that GA could be a perfect aerogel matrix for the fabrication of GA/RDX nanostructured energetic composite due to its unique nano-porous structure and attributes. It was also demonstrated that RDX homogeneously disperses in the as-prepared GA/RDX nanostructured energetic composite at nanometric scale. GA showed promising catalytic effects for the thermal decomposition of RDX. After incorporating with GA, the decomposition of RDX was obviously accelerated.
Co-reporter:Limin Gu and Yunjun luo
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 9) pp:2431
Publication Date(Web):February 20, 2015
DOI:10.1021/ie5045692
A series of halogen-free phosphorus-containing flame-retardant waterborne polyurethanes (DPOWPUs) were synthesized by comodification with Exolit OP550 and ODDP (a phosphorus–nitrogen flame retardant with biphosphonyl structure), and the structure of DPOWPU was characterized. In addition, the thermal decomposition mechanism of DPOWPU was obtained. With the incorporation of OP550 acting as soft segment flame retardant, the decomposition temperatures of each degradation stage decreased. When the OP550 content reached 13 wt %, the limiting oxygen index increased to 31.4%. The cone calorimetery results of materials were greatly improved. Furthermore, the carbon yields of the DPOWPUs increased distinctly, and the firm char layer could much more efficiently protect the unburned materials and prevent the transmission of mass and heat during thermal decomposition. In addition, the phosphorus content of carbon residues grew progressively, which showed that Exolit OP550 displayed condensed phase flame retardation.
Co-reporter:Ting-Ting Li, Yong-Chen Gao, Jin-Xiu Zhou, Mu-Hua Huang and Yun-Jun Luo
RSC Advances 2015 vol. 5(Issue 103) pp:84547-84552
Publication Date(Web):02 Oct 2015
DOI:10.1039/C5RA14860J
Red emitting materials containing D(donor)–A(acceptor) systems with “pyramid-mimetic” structures often gave intensive red fluorescence in the solid state. However, there is no guiding approach to fix such conformations of bisindolylmaleimides (BIMs) in the solid state. In this paper, the location of N-dodecyl chains on indole rings of BIMs was found to have the “pyramid-mimetic” structure and thus gave intensive solid-state red fluorescence in single crystals.
Co-reporter:Gang Wu, Jinqing Li, Chunpeng Chai, Zhen Ge, Jialun Lin and Yunjun Luo
RSC Advances 2015 vol. 5(Issue 118) pp:97710-97719
Publication Date(Web):05 Nov 2015
DOI:10.1039/C5RA12975C
A series of novel flame-retardant waterborne polyurethanes with a phosphorus-containing flame retardant diamine (AWPUs) were synthesized by the method of post-chain extension and the effect of the chain extender on the properties of AWPU dispersions were investigated. The results revealed that the chain extension increased the molecular weight and the molecular weight distribution. The emulsions AWPUs still maintained their stability and particle sizes increased after post-chain extension. AWPUs with a post-chain extension of bis(4-aminophenoxy)phenyl phosphine oxide were successfully prepared and characterized using FTIR and NMR analysis. The hydrogen bonds in hard segments and the phase separation between hard segments and soft segments were enhanced. Moreover, the phosphorus-containing chain extender improved the tensile strength but decreased the elongation at break. With the increase of chain extension ratio, the glass transition temperature for hard segments showed an increasing trend but the glass transition temperature for soft segments showed a decreasing trend. The phosphorus-containing chain extender reduced the thermal stability of AWPUs and favored the degradation of AWPUs. Finally, the flame retardancy was improved with the flame-retardant extender added.
Co-reporter:Yan Li;Jian Zheng;Hong Zhou;Qingchun Wang
Journal of Applied Polymer Science 2015 Volume 132( Issue 40) pp:
Publication Date(Web):
DOI:10.1002/app.42374
ABSTRACT
The thermal stability of the resin matrix is an important factor affecting the safety performance of fiber-reinforced bulletproof composites (FRBCs) during their service period. In this study, two kinds of waterborne polyurethanes based on polyester diol (PEDL218) and isophorone diisocyanate were synthesized; these were used as the matrix of para-aramid FRBCs. Their thermal stability and thermal decomposition behaviors in a nitrogen atmosphere were studied by dynamic thermogravimetric analysis techniques. The kinetic parameters, including the activation energy (E) and pre-exponential factor (A), were calculated by the Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Kissinger, and Šatava–Šesták methods. The results show that the cationic waterborne polyurethane with quaternary ammonium groups has better thermal stability than the anionic waterborne polyurethane with carboxylate groups. Their nonisothermal decomposition mechanisms were studied, and the kinetic parameters were also calculated; this will offer theoretical reference for the manufacturing and application of FRBCs based on waterborne polyurethane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42374.
Co-reporter:Limin Gu;Zhen Ge;Muhua Huang
Journal of Applied Polymer Science 2015 Volume 132( Issue 3) pp:
Publication Date(Web):
DOI:10.1002/app.41288
ABSTRACT
A novel phosphorus−nitrogen flame retardant, octahydro-2,7-di(N,N-dimethylamino)-1,6,3,8,2,7-dioxadiazadiphosphecine (ODDP), with bi-phosphonyl in a cyclic compound, was synthesized by the reaction of POCl3, NH(CH3)2·HCl with OHCH2CH2NH2 in CH2Cl2 solution, and characterized by Fourier transform infrared spectrometer, nuclear magnetic resonance, and mass spectrum. ODDP has been successfully reacted with polyurethane (PU) as a chain extender to prepare phosphorus–nitrogen synergistic halogen-free flame-retardant waterborne PU (DPWPU). Limiting oxygen index (LOI), UL-94, thermogravimetric analysis and scanning electron microscopy suggest the excellent flame retardancy of the DPWPU polymer. When the content of ODDP was 15 wt %, the LOI of DPWPU was 30.6% and UL-94 achieved a V-0 classification. Compared with the unmodified WPU, the thermodecomposition temperature of the DPWPU was reduced and the amount of carbon residue was increased to 18.18%. The surface of carbon residue was shown to be compact and smooth without holes, which would be favorable for resisting oxygen and heat. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41288.
Co-reporter:Zaijuan Zhang;Nan Luo;Zhen Wang
Journal of Applied Polymer Science 2015 Volume 132( Issue 23) pp:
Publication Date(Web):
DOI:10.1002/app.42026
ABSTRACT
PGN-based ETPUEs were synthesized using mixture of chain extenders including 1, 4-butanediol and Diethyl Bis(hydroxymethyl)malonate (DBM). Through the special chain extenders DBM, the –COOR was introduced into the energetic thermoplastic polyurethane elastomers (ETPUEs) and further enhances the adhesion between ETPUE and nitramine solid ingredients in propellants. From the analysis, with the percentage of DBM increasing, the work of adhesion (Wa) between nitramine solid ingredients and ETPUEs increased and the maximum stress (σm) of ETPUEs decreased on the other hand. In order to test the bonding functions of different ETPUEs, the RDX/ETPUE propellants were prepared and the stress–strain curves of all propellants were tested. The results showed that the ETPUE-75 with 75% DBM can prevent the dewetting and improve the mechanical properties of propellants. The ETPUE prepared with chain extender including 1, 4-butanediol and DBM were valuable for application in propellants. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42026.
Co-reporter:Zaijuan Zhang;Gang Wang;Zhen Wang;Yilu Zhang;Zhen Ge
Polymer Bulletin 2015 Volume 72( Issue 8) pp:1835-1847
Publication Date(Web):2015 August
DOI:10.1007/s00289-015-1375-7
The energetic thermoplastic elastomers (ETPE) of glycidyl azide polymer with bonding functions were synthesized by using mixture of chain extenders including 1,4-butanediol and N-(2-cyanoethyl) diethanolamine. From FTIR results, the ability of ETPEs to form hydrogen bond weakened with the percentage of N-(2-cyanoethyl) diethanolamine increasing, which further lead to the decrease of maximum stress of ETPEs and increase of elongation at break. On the other hand, the interfacial interactions between solid ingredients and ETPEs were enhanced owing to the more –CN content. With the percentage of N-(2-cyanoethyl) diethanolamine increasing, two factors affect the adhesion between binder and fillers at the same time. The RDX/ETPE propellants were synthesized and the mechanical properties of them showed that the ETPE-50 with bonding functions can effectively prevent the dewetting, and then improve the mechanical properties of propellants. That is, when the percentage of N-(2-cyanoethyl) diethanolamine was 50 %, the synthesized ETPEs had not only binding function but also bonding interaction.
Co-reporter:Chunpeng Chai;Fangfang Yin;Guoping Li
Science China Chemistry 2015 Volume 58( Issue 6) pp:1021-1026
Publication Date(Web):2015 June
DOI:10.1007/s11426-015-5372-3
The effects of mesogen-jacketed liquid crystalline polymer poly(dipropyl vinylterephthalate) (PDPVT) on the mechanical and thermal properties of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin were investigated by impact test, tensile test and thermogravimetric analysis (TGA). The mechanism underlying the enhancement of mechanical properties of epoxy resin was studied using 1D wide-angle X-ray diffraction (WAXD) and scanning electron microscope (SEM). It was found that the mechanical properties of 1 wt%–5 wt% PDPVT/DGEBA composites were significantly improved compared to neat epoxy resin. Especially, the epoxy resin with 3 wt% PDPVT had the greatest increase in mechanical properties, with the impact strength, tensile strength and elongation while breaking increased by 87%, 59% and 174%, respectively. The increased mechanical strength was due to the fact that PDPVT maintained liquid crystalline phase in cured PDPVT/DGEBA composites, which would blunt the crack tip and prevent crack propagation. Moreover, PDPVT had slight effect on the thermal stability properties of epoxy resin.
Co-reporter:Guoping Li;Menghui Liu;Ran Zhang;Lianhua Shen
Colloid and Polymer Science 2015 Volume 293( Issue 8) pp:2269-2279
Publication Date(Web):2015 August
DOI:10.1007/s00396-015-3620-x
Fuel or oxidant composites were trapped in the holes of poly(azide glycidyl ether) (GAP) gel skeleton network on nano-scale, which could effectively increase the contact area, decrease the transport distance, and make the energy release more close to the ideal state to achieve the maximum power of energetic materials. In this study, GAP gels with three dimensional nano-network structures were prepared by sol–gel method using GAP as precursors and hexamethylene diisocyanate (HDI) as curing agent. The obtained gels were well characterized by Brunauer–Emmett–Teller (BET).The results showed that the specific surface area and dominant pore size were about 41.78 m2/g and 5 ~ 30 nm, respectively. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) could be crystallized in the pore of GAP gel skeleton, so RDX/GAP nano-composite materials were prepared by solute crystallization in combination with a modified drying technology. The average grain size of RDX in GAP network was 20 ~ 46 nm. With the increase of the loadings of RDX, the specific surface area of GAP/RDX nano-composite materials decreased, and the thermal decomposition temperature of RDX in RDX/GAP nano-composite materials decreased by 33 ~ 37 °C. The decomposition heat and explosion heat of RDX(40 wt%)/GAP nano-composite materials were higher by over 13.9 and 19.3 % than those of RDX(40 wt%)/GAP physical blend materials, respectively. Furthermore, the sensitivity of RDX(40 wt%)/GAP nano-composite materials was lower than that of physical blend materials according to the results from our impact sensitivity test.
Co-reporter:Yuanfei Lan;Miaomiao Jin
Journal of Sol-Gel Science and Technology 2015 Volume 74( Issue 1) pp:161-167
Publication Date(Web):2015 April
DOI:10.1007/s10971-014-3590-3
A novel graphene aerogel (GA)/ferric oxide (Fe2O3)/ammonium perchlorate (AP) nanostructured energetic composite was prepared by a facile sol–gel method and supercritical carbon dioxide drying technique. In this study, the morphology and structure of the obtained GA/Fe2O3/AP nanostructured energetic composite were characterized by scanning electron microscopy, nitrogen sorption tests and X-ray diffraction. The thermal decomposition characteristic was investigated by thermogravimetry and differential scanning calorimetry. The results demonstrated that Fe2O3 and AP dispersed in the as-prepared energetic composite at nanometer, showing promising catalytic effects for the thermal decomposition of AP. For the nanostructured energetic composite, GA and Fe2O3 played a catalytic role in the thermal decomposition of AP. Only one decomposition step was observed, instead of two, which was common in previous report. The decomposition temperature of the nanocomposite was obviously decreased as well. Moreover, the total heat release increased significantly. The experimental results showed that the as-prepared GA/Fe2O3/AP nanostructured energetic composite could be a promising candidate material for the solid propellants.
Co-reporter:Miaomiao Jin;Gang Wang;Jingke Deng
Journal of Sol-Gel Science and Technology 2015 Volume 76( Issue 1) pp:58-65
Publication Date(Web):2015 October
DOI:10.1007/s10971-015-3750-0
A new nano-composite energetic material, in which submicrometer ammonium perchlorate (AP) particles and nanoparticles of cyclotrimethylene trinitramine (RDX) were uniformly dispersed in the cross-linked nitrocellulose (NC), was prepared by the sol–gel method. The structure of the material was confirmed by means of SEM, XRD and N2 adsorption isotherm techniques, and the results showed that the NC/RDX/AP nano-composite energetic material is monolithic with numerous pores of nanometer scale and the mean grain size of RDX is <100 nm. The properties of the material were studied by TG/DSC and oxygen bomb calorimetry. TG/DSC analyses indicated that firstly RDX decomposed along with NC matrix and the DSC exothermic peak temperature of NC matrix and RDX is 10 °C lower than that of the physical mixture and secondly the exothermic peak temperature of AP component shifts from the lower temperature of NC matrix and RDX decomposition to the higher temperature of AP decomposition as the AP mass ratio increases. The heat-of-explosion tests showed that the NC/RDX/AP nano-composite energetic materials produced more energy during explosion and the sensitivity of them is lower than that of the physical mixture according to the impact sensitivity test.
Co-reporter:Zaijuan Zhang;Gang Wang;Nan Luo;Muhua Huang;Miaomiao Jin
Journal of Applied Polymer Science 2014 Volume 131( Issue 21) pp:
Publication Date(Web):
DOI:10.1002/app.40965
ABSTRACT
Energetic thermoplastic elastomers (ETPEs) are futuristic binders for propellant/explosive formulations. Poly(glycidyl nitrate) (PGN)-based ETPEs have excellent performance, including a high energy and high oxygen content. PGN-based ETPEs were synthesized on PGN as a soft segment and hexamethylene diisocyanate extended 1,4-butanediol as a hard segment by a prepolymerization method. The thermal behavior of the PGN-based ETPEs was investigated by thermogravimetric analysis (TGA) and derivative thermogravimetry. A fitting strategy was adopted to study every stage of decomposition. The results show that the ETPEs had four main decomposition processes, and the peaks of each stage were at 212, 262, 322, and 414°C. The gas products were tested by TGA/Fourier transform infrared spectroscopy/mass spectrometry, and the main gas products of the samples were N2O, CH2O, C2H4O, and CO2. The previous results indicate the proposed mechanism of thermal decomposition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40965.
Co-reporter:LianHua Shen;GuoPing Li;Kun Gao;Zhen Ge
Science China Chemistry 2014 Volume 57( Issue 6) pp:797-802
Publication Date(Web):2014 June
DOI:10.1007/s11426-013-5050-2
A sol-gel synthetic approach combined with an ultrasonic method was utilized to prepare Al/B/Fe2O3 nanothermites. The structure and properties of the prepared nanothermites were characterized by thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and an impact sensitivity test. The results verified that the nano-aluminum and the micro-boron were uniformly dispersed in the pores of the iron oxide gel. The heat of the prepared Al/B/Fe2O3 nanothermites was 1.3 times that of the simple physically mixed sample. In addition, the heat of the combustion test showed that these materials were indeed energetic. Small-scale safe experiments also showed that the prepared materials through sol-gel were relatively insensitive to standard impact.
Co-reporter:Kun Gao;Guoping Li;Lu Wang
Journal of Thermal Analysis and Calorimetry 2014 Volume 118( Issue 1) pp:43-49
Publication Date(Web):2014 October
DOI:10.1007/s10973-014-3955-4
A novel ammonium perchlorate (AP)/aluminum (Al)/iron oxide (Fe2O3) nano-thermites was prepared by orderly using sol–gel, wet impregnation, and solvent-anti-solvent processes. Samples prepared in this work were characterized by scanning electron microscope (SEM), nitrogen adsorption–desorption tests, X-ray diffraction (XRD), and differential scanning calorimetric (DSC) measurements. The results showed that AP and nano-aluminum were dispersed in the pores of the iron oxide gel, resulting in a large specific surface area (84.7 m2 g−1). The XRD results showed that AP dispersed homogeneously in the energetic composites at nano-scale. DSC analyses indicate that the Al/Fe2O3 nano-thermites played a catalytic role in the thermal decomposition of AP, thus the interaction of thermite reaction was greatly enhanced by accelerated decomposition of AP. The experimental results showed that the as-prepared AP/Al/Fe2O3 nano-thermites were of high energy, making it a competitive candidate material in the field of micro-propellants.
Co-reporter:Y. Zhang, C.P. Chai, Y.J. Luo, L. Wang, G.P. Li
Materials Science and Engineering: B 2014 Volume 188() pp:13-19
Publication Date(Web):October 2014
DOI:10.1016/j.mseb.2014.06.002
•Fe3O4 aerogels possess quite low density and large specific surface area.•The porous Fe3O4 aerogels show superparamagnetism and high saturation magnetization.•We study the influences of concentration, molar ratios of reactants and calcinations on the textural and magnetic properties.•The porous material with electromagnetic properties can be a microwave absorbent.The Fe3O4 aerogels have been prepared by the sol–gel method and subsequent supercritical drying with CO2, FeCl3·6H2O, FeCl2·4H2O and propylene oxide was used as precursor and gelling accelerator, respectively. The result from XRD indicated that the aerogels were composed of nano-crystals. XPS was employed to further characterize the structure of products and confirmed the existence of Fe and O. SEM and TEM showed a fine microstructure of the as-prepared aerogels with three dimensional network, and the skeletons of aerogels were consist of interconnected nanoparticles. The Fe3O4 aerogels also possessed quite low density (0.249–0.393 m2 g−1), large specific surface area (60.26–330.20 m2 g−1) and superior saturation magnetization (14.64–52.28 emu g−1). Moreover, the textural and magnetic properties of the aerogels could be controlled by solution concentration, molar ratio of propylene oxide (PO) to Fe3+ and calcination temperature. The fabricated Fe3O4 aerogels exhibited certain electromagnetic properties in the frequency range of 2–18 GHz, and the maximum value of tan δe and tan δm is 0.07 and 0.27, respectively.
Co-reporter:Guoping Li;Wenting Lu;Min Xia;Chunpeng Chai ;Xiaoqing Wang
Chinese Journal of Chemistry 2012 Volume 30( Issue 3) pp:541-546
Publication Date(Web):
DOI:10.1002/cjoc.201100170
Abstract
Using a successive method, PAMAM dendrimer-encapsulated bimetallic PdPt nanoparticles have been successfully prepared with core-shell structures (Pd@Pt DENs). Evidenced by UV-vis spectra, high resolution transmission electron microscopy, and X-ray energy dispersive spectroscopy (EDS), the obtained Pd@Pt DENs are monodispersed and located inside the cavity of dendrimers, and they show a different structure from monometallic Pt or Pd and alloy PdPt DENs. The core-shell structure of Pd@Pt DENs is further confirmed by infrared measurements with carbon monoxide (IR-CO) probe. In order to prepare Pd@Pt DENs, a required Pd/Pt ratio of 1:2 is determined for the Pt shell to cover the Pd core completely. Finally, a mechanism for the formation of Pd@Pt DENs is proposed.
Co-reporter:Xuetong Zhang, Zhuyin Sui, Bin Xu, Shufang Yue, Yunjun Luo, Wanchu Zhan and Bin Liu
Journal of Materials Chemistry A 2011 vol. 21(Issue 18) pp:6494-6497
Publication Date(Web):01 Apr 2011
DOI:10.1039/C1JM10239G
Mechanically strong and electrically conductive graphene aerogels can be prepared by either supercritical drying or freeze drying of hydrogel precursors synthesized from reduction of graphene oxide with L-ascorbic acid, and the resulting graphene aerogels possess the specific capacitance of 128 F g−1 with superior rate performance.
Co-reporter:Xuetong Zhang, Chunyan Li, and Yunjun Luo
Langmuir 2011 Volume 27(Issue 5) pp:1915-1923
Publication Date(Web):January 19, 2011
DOI:10.1021/la1044333
Porous conducting polymers are of great interest because of the huge potential to combine high surface areas in the dry state with physical properties relevant to organic electronics. Aligned or unaligned conducting polymer cryogels with 3D macroporous architectures have been prepared using the ice-segregation-induced self-assembly (ISISA) of different poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) freezing precursors as a dispersion or a formed hydrogel. The chemical composition and molecular structure of the resulting conducting polymer cryogels have been investigated by X-ray photoelectron spectroscopy and Raman spectroscopy, respectively. The morphologies of the PEDOT-PSS cryogels, together with their textural structures, have been revealed by scanning electron microscopy, mercury porosimetry, and nitrogen sorption tests. Processing PEDOT-PSS via ISISA endows the conducting polymers with novel properties, as demonstrated by a series of X-ray diffraction, differential scanning calorimetry, and electrical conductivity tests. These conducting polymer cryogels with aligned/unaligned macroporous architectures suggest the potential in the development of electronic components, tissue engineering, and next-generation catalytic and separation supports.
Co-reporter:Guoping Li, ;Wenting Lu;Jie Li;Yujuan Jin ;Sufang Guo
Chinese Journal of Chemistry 2010 Volume 28( Issue 4) pp:633-638
Publication Date(Web):
DOI:10.1002/cjoc.201090125
Abstract
G5.0-OH PAMAM dendrimers were used to prepare fluorescent silver clusters with weaker ultraviolet irradiation reduction method, in which the molar ratio of Ag+ to PAMAM dendrimers was the key factor to determine the geometry and properties of silver nanoparticles. The results showed that because of G5.0-OH PAMAM dendrimers as strong encapsulatores, when the molar ratios of Ag+ to PAMAM dendrimers was smaller than 5, the obtained Agn clusters (n<5) had line structures and "molecular-like" properties, which were highly fluorescent and quite stable in aqueous solution. Whereas when the molar ratios were between 5 and 8, the obtained Agn clusters were 2D structures and their fluorescence was weaker. When the molar ratio was larger than 8, the structure of silver nanoparticles was 3D and no fluorescence was observed from the obtained silver nanoparticles.
Co-reporter:Wenting Lu;Guoping Li;Yujuan Jin
Journal of Applied Polymer Science 2009 Volume 112( Issue 5) pp:2854-2858
Publication Date(Web):
DOI:10.1002/app.29780
Abstract
Poly(amidoamine) (PAMAM) dendrimers have attracted attention because of their well-defined molecule structures and chemical versatility, which also complicate the mechanism of interactions between metal ions and PAMAM dendrimers. To further understand the complexation of dendrimers with metal ions, the interactions between Pd2+ ions and G4.5-COOCH3 PAMAM dendrimers were investigated by UV-vis and FTIR spectrophotometric method. The results show that the addition of K2PdCl4 results in covalent attachment of the PdCl alcoholysis product of this complex to tertiary amines within the dendrimers under the appropriate conditions. This process was also supported by X-ray photoelectron spectroscopy data of the new complex which indicated a 1 : 3 Pd/Cl ratio. The maximum loading of 80 Pd2+ ions within the G4.5-COOCH3 dendrimers and the best pH value of 8.3 for complexation system are also obtained. Details regarding the Pd species present in solution of different chemical environments are reported. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Wei Xin, Yunjun Luo, Xuejing Song, Jingru Liu, Yin Yang, Yong Lv, Yongbin Jiu
Journal of Membrane Science 2008 Volume 325(Issue 2) pp:592-598
Publication Date(Web):1 December 2008
DOI:10.1016/j.memsci.2008.08.031
Pervaporation membranes containing hyperbranched polymer were prepared from the blends of ethyl cellulose (EC) and hyperbranched polyester (HBPE). The FT-IR analysis indicated that the interactions between EC and HBPE decreased as increasing the generation of HBPE. The membrane containing HBPE (EC-HBPE) showed both higher sorption ratio and selectivity than pure EC membrane. The effects of HBPE content as well as temperature of feed solutions on the membrane performance were investigated in detail. The EC-HBPE membrane exhibited much higher permeate flux than the EC membrane, while the separation factor maintained at same level.
Co-reporter:He Chen;Chunpeng Chai;Jiong Wang;Jie Li ;Min Xia
Journal of Applied Polymer Science 2008 Volume 110( Issue 5) pp:3107-3115
Publication Date(Web):
DOI:10.1002/app.28841
Abstract
A series of waterborne polyurethanes (WPUs) with different contents of reactive organophosphonate were well prepared. Their structures were characterized by Fourier transform infrared and 1H-NMR spectroscopy. Thermogravimetry and derivative thermogravimetry revealed that the WPU films containing phosphorus possessed lower onset and maximum degradation temperatures but higher char yields. Differential scanning calorimetry analysis suggested phase mixing of the hard and soft domains. The mechanical properties decreased with increasing amount of organophosphonate, whereas the limiting oxygen index results of the WPU films indicate that the flame retardancy was improved significantly by the incorporation of organophosphonate. The water uptake values of the organophosphonate-containing WPU films were higher than those of the phosphorus-free ones, whereas the static contact angles of the films indicated that the surface hydrophilic properties were not affected by segmenting in this phosphorus-containing oligomer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Yu-Juan Jin, Yun-Jun Luo, Guo-Ping Li, Jie Li, Yuan-Feng Wang, Rui-Qin Yang, Wen-Ting Lu
Forensic Science International 2008 Volume 179(Issue 1) pp:34-38
Publication Date(Web):18 July 2008
DOI:10.1016/j.forsciint.2008.04.010
Uniform and well-dispersed photoluminescent semiconductor CdS (cadmium sulfide) QDs (quantum dots) were in situ prepared inside Generation 4.0-NH2 PAMAM (polyamidoamine) dendrimers in methanol, methanol and water mixed solutions of volume ratio 1:9, respectively. The prepared solutions containing photoluminescent semiconductor CdS QDs were utilized for detection of cyanoacrylate ester fumed fingerprints on tinfoil. The results show that fumed latent fingerprints treated with prepared CdS/PAMAM nanocomposites in methanol, 1:9 methanol:water mixed solutions emit pale yellow–green and orange luminescence respectively under ultraviolet excitation of 365 nm from an UV LED. Fumed fingerprints were successfully detected with good resolving rate and the mechanism was studied in detail.
Co-reporter:Guoping Li, Lianhua Shen, Yunjun Luo, Shaomin Zhang
Desalination (1 April 2014) Volume 338() pp:115-120
Publication Date(Web):1 April 2014
DOI:10.1016/j.desal.2014.02.001
•Silver-PAMAM dendrimer nanocomposite was used to modify the PVDF membrane.•Ag DENPs on PVDF membranes improve hydrophilicity.•Ag DENPs can improve anti-fouling properties of PVDF membranes.•The structure and properties of PAMAM dendrimers play an important role on the performance improvement of PVDF membranes.The highly hydrophobic property of PVDF membranes makes them prone to fouling, so hydrophilic additives are frequently used to improve their hydrophilicity and anti-fouling performance. In this study, silver nanoparticles were prepared by using PAMAM dendrimers as templates to form silver-PAMAM dendrimer nanocomposites (Ag DENPs), which have amine terminated groups and good hydrophilicity and antibacterial performance. So Ag DENPs were used to improve the hydrophilicity and anti-fouling performance of PVDF membranes. Judging from the result of SEM measurement, Ag DENPs increased the surface roughness and decreased the pore size of PVDF membranes. According to the result of water static contact measurement, Ag DENPs made a significant improvement in PVDF membrane surface hydrophilicity. And one possible explanation on the improvement of PVDF membrane surface hydrophilicity with Ag DENPs was firstly proposed. Membrane permeation and anti-bacterial tests were carried out to characterize the antifouling performance of PVDF membranes. Flux recovery ratio (FRR) increased about 40% in the presence of Ag DENPs on the PVDF membrane surface, which elucidated that the anti-organic fouling performance of PVDF membranes was elevated. Simultaneously, the Ag DENPs–PVDF membranes were better suited to capture HA than BSA. Anti-bacterial test confirmed that Ag DENPs–PVDF membranes showed superior anti-biofouling activity.
Co-reporter:Xuetong Zhang, Zhuyin Sui, Bin Xu, Shufang Yue, Yunjun Luo, Wanchu Zhan and Bin Liu
Journal of Materials Chemistry A 2011 - vol. 21(Issue 18) pp:NaN6497-6497
Publication Date(Web):2011/04/01
DOI:10.1039/C1JM10239G
Mechanically strong and electrically conductive graphene aerogels can be prepared by either supercritical drying or freeze drying of hydrogel precursors synthesized from reduction of graphene oxide with L-ascorbic acid, and the resulting graphene aerogels possess the specific capacitance of 128 F g−1 with superior rate performance.
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