Co-reporter:Junshuo Cui
Journal of Nanoparticle Research 2017 Volume 19( Issue 11) pp:357
Publication Date(Web):27 October 2017
DOI:10.1007/s11051-017-4047-8
Dispersion of graphene with high effectiveness is a great challenging task. In this paper, a series of water-soluble polyamine-functionalized perylene bisimide derivatives (HAPBI) were synthesized and further used as the stabilizer of graphene in water. It was found that the number of amine group strongly determined the water solubility of HAPBI and its effectiveness on stabilizing graphene. With triethylenetetramine-functionalized perylene bisimide (HAPBI-3), high concentration of aqueous graphene dispersion up to 1.0 mg mL−1 was obtained at the weight ratio of HAPBI-3 to graphene even down to 1:3, demonstrating its higher efficiency to the common surfactants, polymer, and other perylene bisimide derivatives reported. Moreover, graphene’s electrical conductivity is less impacted compared with polyvinylpyrrolidone (PVP), particularly favoring for its further application. Careful inspection indicated that HAPBI-3 molecules strongly interacted with graphene in a process of de-assembly of their self-aggregates and subsequently irreversible restacking on graphene sheets.
Co-reporter:Fei Xu, Tao Wang, HongYu Chen, James Bohling, Alvin M. Maurice, Limin Wu, Shuxue Zhou
Progress in Organic Coatings 2017 Volume 113(Volume 113) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.porgcoat.2017.08.005
•Double layer self-cleaning coatings composed of a TiO2-based clear top coat and a latex film underneath were prepared.•Double layer coatings displayed good self-cleaning property in outdoor exposure test.•The top photocatalytic coatings with appropriate TiO2 content did not lead to photocatalytical degradation of the latex coatings underneath.Photocatalytic TiO2 provides a promising route to produce self-cleaning coating surfaces, but it often causes decomposition of organic substrates and other coating components. An interlayer is often employed to insulate photocatalytic activity from sensitive substrate layers, complicating the application of these self-cleaning coatings. Herein, photocatalytic TiO2-based coatings were prepared based on an aqueous TiO2 dispersion in a hybrid binder synthesized from tetraethyl orthosilicate and methyl trimethoxy silane via a sol-gel process. Coatings with various levels of nano TiO2 were prepared and found to be transparent to visible light; i.e., the clear coating could be directly cast on architectural latex coatings without changing its original appearance. The photocatalytic coating system was composed of a TiO2-based clear top coat and an opaque latex film underneath. The coatings were evaluated through outdoor exposure studies and accelerated weathering tests.Results of these tests showed that the photocatalytic coatings with a TiO2 content range of 33–45% exhibited excellent self-cleaning performance, while displaying none of the expected degradation. In fact, this nano TiO2-based clear coating actually protected the latex film from UV-induced damage. The increased stability of the organic film may have resulted from reduced UV transmission through the photo-catalyst containing clear coat as well as reduced water permeability. It was demonstrated that the combination of appropriate TiO2 content and a suitable binder are crucial for the fabrication of robust photocatalytic self-cleaning coatings for painted surfaces without the need for an interlayer.Download high-res image (241KB)Download full-size image
Co-reporter:Yunjiao Gu;Jiahua Yang
Journal of Materials Chemistry A 2017 vol. 5(Issue 22) pp:10866-10875
Publication Date(Web):2017/06/06
DOI:10.1039/C7TA01499F
Oil contamination is problematic in subaqueous environments. It is difficult to prepare long-lasting textured superhydrophilic/underwater oil-repellent coatings without using a sophisticated method. Here, an ultra-facile and low-cost immersion-curing approach has been developed to generate superhydrophilic and underwater superoleophobic coatings from poly(vinyl alcohol) (PVA)/silica (SiO2) nanocomposites. During immersion curing, polymeric dissolution occurs simultaneously with crosslinking but occurs solely at the topmost layer, and helps to create enriched hierarchical surface micro-/nanostructures. Hence, superhydrophilicity is attainable for nanocomposite coatings with a filler percentage of only 15 wt%. Immersion-cured PVA/SiO2 nanocomposite coatings with 35 wt% silica have an excellent underwater superoleophobicity in terms of durability and ultra-low oil adhesion towards a variety of oils, including viscous crude oil. Because of its lower filler content and confined porous structure, this coating has a greater transparency compared with its conventional blend-curing underwater superoleophobic counterpart. Immersion-cured nanocomposite coatings display an excellent mechanical durability based on pencil hardness (3H) and sand-abrasion performance. The extra acrylic/melamine base-coat allows the underwater superoleophobic PVA/SiO2 coatings to be applied to diverse substrates, including glass, metals, and plastics, and renders them free from oil in aqueous environments.
Co-reporter:Yang Yang;Huali Luo;Jinlong Yang;Daofen Huang
Journal of Applied Polymer Science 2016 Volume 133( Issue 39) pp:
Publication Date(Web):
DOI:10.1002/app.43972
ABSTRACT
Construction of a highly hydrophilic polymer surface with excellent long-term stability underwater is a great challenge. In this paper, a facile ultraviolet (UV) curing technique was employed to realize the three-dimensional (3D) grafting of poly(ethylene glycol) diacrylate (PEGDA, molecular weight: 400, 600, and 1000 g/mol) on a bisphenol A epoxy acrylate (BEA) sheet. The cross section morphology, surface chemical composition, and wettability of the sheets were monitored using an optical microscope, an attenuated total reflectance Fourier transform infrared spectroscope, and a water contact angle analyzer, respectively. The PEGDA-grafted epoxy sheets displayed a highly hydrophilic surface and meanwhile possessed excellent stability underwater, despite the molecular weight of PEGDA. In contrast, the PEGDA/BEA blend sheets are easily damaged underwater, due to strong swelling. In addition, the PEGDA1000-grafted BEA sheet demonstrated good antifouling performance in a natural marine environment. Nevertheless, its long-term antifouling is not satisfactory, being presumably due to hydrolysis or biodegradation of the PEG segments. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43972.
Co-reporter:Yunjiao Gu;Huali Luo;Limin Wu;Wei Gao;Jinlong Yang
Journal of Polymer Science Part B: Polymer Physics 2016 Volume 54( Issue 16) pp:1612-1623
Publication Date(Web):
DOI:10.1002/polb.24064
ABSTRACT
Controllable phase segregation adjustment for immiscible polymer blends has always been tough, which hinders the development of amphiphilic antifouling coatings from more accessible blends. Herein, methacrylated poly(dimethylsiloxane) (PDMS-MA) was synthesized and mixed with poly(ethylene glycol)methylether methacrylate (PEG-MA). It was interestingly discovered that these PDMS-MA/PEG-MA blends displayed upper critical solution temperatures (UCST) due to thermo-induced conformational change of PEG-MA and the UCST changed with PDMS-MA/PEG-MA mass ratios. Micro-/nano-phase segregation, nanophase segregation, or homogenous morphology were therefore achieved. These PDMS-MA/PEG-MA blends with different mass ratios were UV-cured under varying temperatures to fabricate coatings. Their surface morphology and wettability are readily adjusted by phase segregation. For the first time, highly hydrophilic surface was achieved for coatings with microphase segregation because of the exposure of PEG-rich domains, which exhibited an enhanced protein resistance against bovine serum albumin (BSA). Anti-bacterial performance (Shewanella loihica) was also observed for these PDMS/PEG coatings. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1612–1623
Co-reporter:Kunlin Chen, Shuxue Zhou, and Limin Wu
ACS Nano 2016 Volume 10(Issue 1) pp:1386
Publication Date(Web):December 21, 2015
DOI:10.1021/acsnano.5b06816
Marine biofouling has been plaguing people for thousands of years. While various strategies have been developed for antifouling (including superoleophobic) coatings, none of these exhibits self-healing properties because the bestowal of a zoetic self-repairing function to lifeless artificial water/solid interfacial materials is usually confronted with tremendous challenges. Here, we present a self-repairing underwater superoleophobic and antibiofouling coating through the self-assembly of hydrophilic polymeric chain modified hierarchical microgel spheres. The obtained surface material not only has excellent underwater superoleophobicity but also has very good subaqueous antibiofouling properties. More importantly, this surface material can recover the oil- and biofouling-resistant properties once its surface is mechanically damaged, similar to the skins of some marine organisms such as sharks or whales. This approach is feasible and easily mass-produced and could open a pathway and possibility for the fabrication of other self-healing functional water/solid interfacial materials.Keywords: antibiofouling; coatings; microgel spheres; self-healing; surface materials; underwater superoleophobic;
Co-reporter:Kunlin Chen;Shu Yang;Limin Wu
Advanced Functional Materials 2015 Volume 25( Issue 7) pp:1035-1041
Publication Date(Web):
DOI:10.1002/adfm.201403496
Superhydrophobic coatings that are also self-healing have drawn much attention in recent years for improved durability in practical applications. Typically, the release of the self-healing agents is triggered by temperature and moisture change. In this study, UV-responsive microcapsules are successfully synthesized by Pickering emulsion polymerization using titania (TiO2) and silica (SiO2) nanoparticles as the Pickering agents to fabricate all-water-based self-repairing, superhydrophobic coatings. These coatings are environmentally friendly and can be readily coated on various substrates. Compared to conventional superhydrophobic coatings, these coatings can regenerate superhydrophobicity and self-cleaning ability under UV light, mimicking the outdoor environment, after they are mechanically damaged or contaminated with organics. They can maintain the superhydrophobicity after multiple cycles of accelerated weathering tests.
Co-reporter:Baozhong Lin, Shuxue Zhou
Applied Surface Science 2015 Volume 359() pp:380-387
Publication Date(Web):30 December 2015
DOI:10.1016/j.apsusc.2015.10.111
Highlights
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A light-responsive silane (NBS) was synthesized based on o-nitrobenzyl group.
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The NBS was used to produce light-responsive silica nanoparticles (SiO2-NBS-F).
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The SiO2-NBS-F exhibited considerable change of wettability after UV irradiation.
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The SiO2-NBS-F can efficiently increase hydrophilicity of fluorocarbon coatings.
Co-reporter:Kunlin Chen and Shuxue Zhou
RSC Advances 2015 vol. 5(Issue 18) pp:13850-13856
Publication Date(Web):22 Jan 2015
DOI:10.1039/C4RA16275G
Fluoroalkyl silane (FAS)-loaded polystyrene microcapsules were prepared via Pickering emulsion polymerization using silica/titania nanoparticles as Pickering agents, wherein the nanoparticles were first modified with a Trixton X-100-tethered silane coupling agent. The microcapsules display rugged surfaces and have average sizes from 150 nm to 890 nm, depending on the nanoparticles-to-oil mass ratio. Under UV exposure, the microcapsules break up and release the encapsulated FAS, demonstrating their UV-responsive ability. The microcapsules were further embedded into waterborne coatings. Monitoring the evolution of the surface wettability of the coatings under UV-exposure indicates that the releasing rate of FAS could be tunable using the content of TiO2 nanoparticles in the microcapsules.
Co-reporter:Kunlin Chen, Shuxue Zhou and Limin Wu
RSC Advances 2015 vol. 5(Issue 127) pp:104907-104914
Publication Date(Web):01 Dec 2015
DOI:10.1039/C5RA22596E
Durability of nonfouling coatings is a critical problem to be solved for their practical application. In this paper, self-repairing nonfouling polyurethane (PU) coating was fabricated by spraying of a triblock copolymer of polyethylene glycol (PEG), 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) on pre-cured acrylic-based PU coatings. The triblock copolymer was synthesized through living radical polymerization mediated by an atom transfer radical polymerization. Anchoring of the copolymer took place both on the surface and in the interior (namely, 3D-grafting) of PU coatings through the diffusion of the copolymer and subsequently the chemical reaction between the pendent hydroxyl group of the copolymer and the remaining isocyanate groups in the pre-cured PU coatings. This 3D grafting procedure is rather simple and favorable for large-area application. The 3D-grafted PU coating has higher hydrophilicity (water contact angle: 33°). In contrast, if the triblock copolymer was used as an additive in PU coatings, the hydrophilicity of the PU coating did not obviously change. The 3D-grafted PU coating effectively inhibited the adhesion of protein and human platelet cells due to the synergistic effect of PEG and MPC. Moreover, after the coatings were detached and mechanically damaged, the surfaces can restore their hydrophilicity and possess better long-term anti-fouling ability than the control surface-grafted coatings underwater.
Co-reporter:Ling Yang, Shuxue Zhou, Limin Wu
Progress in Organic Coatings 2015 Volume 85() pp:208-215
Publication Date(Web):August 2015
DOI:10.1016/j.porgcoat.2015.04.012
•TiO2@PMMA core/shell latex was synthesized using miniemulsion polymerization.•Waterborne self-cleaning coating was made from TiO2@PMMA latex and modified silica.•The coating was fast to attain superhydrophilic surface under UV-irradiation.•The coatings are excellent in photocatalytic activity, durability, and transparency.Titania/poly(methyl methacrylate) core/shell (TiO2/PMMA) latex was synthesized by miniemulsion polymerization and further mixed with modified colloidal silica to create waterborne nanocomposite coatings (M-SiO2/TiO2/PMMA). The coatings were undergone accelerated weathering tests and their surface wettability, transparency, and morphology were monitored as a function of weathering time. Superhydrophilic surfaces were attained after 27–34 h aging, being attributed to the unique distribution of TiO2 nanoparticles in PMMA phase. In contrast to the coating based on the mixture of M-SiO2, TiO2 nanoparticles, and PMMA latex, this time is quite short and absolutely benefit for their outdoor application. Due to the degradation of organic matrix, transparency reduction and film thickness loss of coatings took place in weathering tests. Nevertheless, these undesired evolutions can be alleviated by decreasing film thickness or using adequate quantity of TiO2/PMMA latex. Photodegradation experiments of methyl blue indicate that the formed superhydrophilic coatings are excellent in self-cleaning performance.
Co-reporter:Ting He
Journal of Coatings Technology and Research 2015 Volume 12( Issue 4) pp:767-776
Publication Date(Web):2015 July
DOI:10.1007/s11998-015-9676-1
Hardness and toughness are typically contradictive for sol–gel-derived coatings. In this article, thick (~15 μm) silicon-oxo-dominated nanocomposite coatings with high transparency were fabricated by incorporating 3-methacryloxypropyltrimethoxysilane (MPS)-modified silica alcosol into a moisture-curable polysiloxane oligomer and curing with the aid of 3-aminopropyltriehtoxysilane (APS). Effects of MPS-to-SiO2 molar ratio, SiO2 nanoparticle content, APS dosage, and curing process on the mechanical properties were thoroughly investigated using a pencil hardness tester, a flexibility tester, and a nanoindentation tester. The best properties were achieved by a coating with an MPS-to-SiO2 molar ratio of 0.1:1, a silica nanoparticle content of 10 wt%, and an APS dosage of 30 wt%. This coating demonstrated enhanced hardness (pencil hardness = 7H and microhardness = 626 MPa) and toughness (excellent flexibility of 5 mm in the mandrel bend test). Additional curing via aza-Michael addition between amino groups from APS and C=C groups from the polysiloxane oligomer can be accomplished at elevated temperatures. This enables further mechanical enhancement, namely hardness (9H and 1087 MPa), with adequate flexibility (10 mm). Such properties are superior to those reported for other sol–gel-derived silicon-oxo coatings produced at low drying temperatures.
Co-reporter:Xiaolong Wang, Shuxue Zhou and Limin Wu
Journal of Materials Chemistry A 2014 vol. 2(Issue 29) pp:5752-5758
Publication Date(Web):30 Apr 2014
DOI:10.1039/C4TC00437J
Fe3+ doped Mg/Al layered double hydroxides (Mg/Al + Fe LDHs) were prepared by a facile solvothermal method. Incorporation of Fe3+ into Mg/Al LDHs can efficiently shift their UV-absorption to cover the entire UV range, allowing them to qualify as a candidate for blocking the whole UV light region (200–400 nm). The as-obtained Mg/Al + Fe LDHs possess intrinsic dispersibility in water, and, moreover, they can be dispersed in an organic solvent (xylene) after being sequentially washed with water/ethanol and then acetone. Accordingly, highly transparent and whole UV-blocking coatings were readily fabricated by incorporating Mg/Al + Fe LDHs into waterborne or solvent-based polysiloxane coatings, or merely using an aqueous Mg/Al + Fe LDH dispersion due to its self-supporting behavior. More importantly, the Mg/Al + Fe LDH-based coatings exhibited long-term UV-shielding performance even after accelerated weathering tests for as long as 800 h.
Co-reporter:Kunlin Chen, Shuxue Zhou and Limin Wu
Chemical Communications 2014 vol. 50(Issue 80) pp:11891-11894
Publication Date(Web):12 Aug 2014
DOI:10.1039/C3CC49251F
A self-repairing superhydrophobic organic coating comprising polystyrene, fluorinated poly(methylsiloxane), fluorinated alkyl silane modified silica nanoparticles and photocatalytic titania nanoparticles shows self-repairing ability after mechanical damage, photocatalytic self-cleaning performance, and thus long-term outdoor durability.
Co-reporter:Xiaolong Wang, Shuxue Zhou and Limin Wu
Journal of Materials Chemistry A 2013 vol. 1(Issue 45) pp:7547-7553
Publication Date(Web):26 Sep 2013
DOI:10.1039/C3TC31479K
This paper presents a facile method for encapsulation of a SiO2 layer on the surfaces of ZnO quantum dots (ZnO QDs) to fabricate ZnO QD@SiO2 nanoparticles. Coating of a SiO2 layer can effectively improve the dispersion of ZnO QDs in an aqueous phase, insulate the photocatalytic activity of ZnO QDs and increase the photoluminescent quantum yield. When the as-obtained ZnO QD@SiO2 nanoparticles were introduced into acrylic latex, highly transparent, excellent UV-shielding and durable waterborne polymer coatings were easily fabricated. Moreover, the polymer coatings can convert UV into blue light effectively, which is beneficial for their application as agricultural films.
Co-reporter:Shuxue Zhou, Xiaofeng Ding, Limin Wu
Progress in Organic Coatings 2013 Volume 76(Issue 4) pp:563-570
Publication Date(Web):April 2013
DOI:10.1016/j.porgcoat.2012.11.013
Ambient-curable superhydrophobic fluoropolysiloxane/TiO2 nanocomposite coatings were prepared simply by blending a hydrophobic binder with TiO2 nanoparticles. The binder consisted of triethoxysilyl-terminated fluoropolysiloxane (FPU), polymethylphenyl-siloxane (PMPS), and 3-aminopropyltriethoxysilane. The surface wettability, morphology, mechanical properties, and artificial weatherability were thoroughly investigated, using contact angle analysis, SEM, AFM, pendulum hardness rocker measurements, and nanoindentation measurements, respectively. Superhydrophobic coatings could be fabricated with FPU/PMPS weight ratios of higher than 1:9, and TiO2 loads of over 35 wt%. The superhydrophobic coatings had good mechanical strength, excellent artificial weathering durability, and resistance to organic contaminants. It was demonstrated that the TiO2 nanoparticles acted both as building blocks for the construction of the micro-/nano-structured surface, and as a photocatalyst for the decomposition of organic contaminants.Highlights► Superhydrophobic coatings were facilely prepared using “one pot method”. ► The coatings have high hardness up to H or 2H even cured at room-temperature. ► The coatings are durable in weathering tests and resistant to organic contaminants. ► The coatings are economic and promising for large-scale practical application.
Co-reporter:Ling Yang;Guangxin Gu ;Limin Wu
Journal of Applied Polymer Science 2013 Volume 129( Issue 3) pp:1434-1445
Publication Date(Web):
DOI:10.1002/app.38827
Abstract
In this article, silica sol (diameter: 8–100 nm) and polymer latex (Tg < 25°C) were mixed and dried at room temperature to prepare nanocomposite films with high silica load (≥50 wt %). Effects of silica size, silica load, and the Tg of the polymer on the film-forming behavior of the silica/polymer latex blend were investigated. The transparency, morphology, and mechanical properties of the nanocomposite films were examined by UV–Vis spectroscopy, SEM, and nanoindentation tests, respectively. Transparent and crack-free films were produced with silica loads as high as 70 wt %. Thirty nanometers was found to be the critical silica size for the evolution of film-forming behavior, surface morphology, and mechanical properties. Colloidal silica particles smaller than this critical size act as binders to form strong silica skeleton. This gives the final silica/polymer nanocomposite film its porous surface and high mechanical strength. However, silica particles with sizes of 30 nm or larger tend to work as nanofillers rather than binders, causing poor mechanical strength. We also determined the critical silica load appeared for the mechanical strength of silica/polymer film at high silica load. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Sainan Li;Guangxin Gu
Journal of Coatings Technology and Research 2013 Volume 10( Issue 3) pp:339-346
Publication Date(Web):2013 May
DOI:10.1007/s11998-012-9462-2
Contamination of exterior coatings with dirt is a significant problem in seriously polluted environments. To correlate the dirt resistance of exterior coatings with surface characteristics (wettability, roughness, and composition), steel topcoats were evaluated using both dirt pick-up tests according to a national standard testing method of China (GB/T 9757-2001) and outdoor exposure experiments in Shanghai, China. These topcoats included polyvinylidene fluoride (PVDF) paints with various water contact angles (WCAs), polyurethane (PU) paint, polysiloxane (PSiO) paint, and 2K fluorocarbon (FPU) paint. Opposite dirt resistance results were obtained from these two dirt pick-up methods. In the outdoor exposure experiments, superhydrophilic PVDF paints showed excellent self-cleaning performance and thus superior dirt resistance. Superhydrophobic PVDF paint exhibited self-cleaning performance initially, but became dirty finally due to a piling up of PM2.5 pollutants. PVDF paints with WCAs of 85°–125°, PU, PSiO, and FPU paints all exhibited poor dirt resistance in the outdoor environment. These results indicate that dirt resistance depends on surface wettability and the characteristics of pollutants rather than on the surface roughness and composition.
Co-reporter:Yinfeng Lu, Shuxue Zhou, Guangxin Gu, Limin Wu
Thin Solid Films 2013 Volume 534() pp:231-237
Publication Date(Web):1 May 2013
DOI:10.1016/j.tsf.2013.02.130
Polysiloxane/tungsten-doped vanadium dioxide [VO2(W)] nanocomposite coatings were prepared by de-agglomerating and modifying the self-made VO2(W) particles with 3-methacryloxypropyltrimethoxysilane in butyl acetate, then mixing MPS-functionalized VO2(W) nanoparticles with polysiloxane oligomers and curing the product at ambient temperature with the aid of 3-aminopropyltriethoxysilane. The VO2(W) particles were obtained by hydrolysis of vanadyl sulfate mingled with tungstate dopant and subsequent calcination. The structure and properties of the VO2(W) particles and nanocomposite coatings were characterized by X-ray diffraction analysis, differential scanning calorimetry, visible-near infrared spectroscopy, pendulum hardness tests, and nanoindentation. The effects of the synthesis conditions and the de-agglomeration process on the properties of the VO2(W) particles were investigated. Crystalline VO2(W) particles were obtained only with an appropriate amount of air and temperature during the calcination step and were easily reduced to nanometer size by bead-milling. The obtained nanocomposite coatings exhibited high transparency, good thermochromic performance, and ultra-high hardness (~ 1.0 GPa).•Thermochromic coatings were prepared with VO2(W) particles and polysiloxane.•Crystalline VO2(W) particles can be reduced to nanosize by bead-milling.•The coatings display transparency of 60% and solar energy moduluation of 23%.•The coatings are ambient-curable, favoring in situ application on windows.
Co-reporter:Xiaobing Chen, Shuxue Zhou, Bo You, Limin Wu
Progress in Organic Coatings 2012 Volume 74(Issue 3) pp:540-548
Publication Date(Web):July 2012
DOI:10.1016/j.porgcoat.2012.01.021
Ambient-curable polysiloxane coatings were prepared by pre-hydrolysis/condensation of phenyltrimethoxysilane (PTMS) and dimethyldimethoxysilane (DMDMS) in the presence of ammonia solution and subsequently mixing with aminopropyltriethoxysilane (APS). The mechanical properties of coatings were thoroughly examined at both macro- and micro-level and the thermal stability of coatings was characterized by thermogravimetic analysis, both of which were correlated with coating composition and the hydrolysis/condensation degree of polysiloxane oligomer. It was found that pro-hydrolysis step is essential for fabrication of thick crack-free coatings (18–35 μm). Higher DMDMS molar ratio, more APS dosage and lower hydrolysis/condensation degree of polysiloxane oligomer favor enhancing the hardness. Excellent impact resistance (50 cm kg) of coatings was obtained at 5% and 10% APS dosage, despite of the type and structure of polysiloxane oligomer. Whatever, the best scratch resistance of coatings was attained using the polysiloxane oligomer, prepared at PTMS-to-DMDMS molar ratio of 2:8 and water-to-precursor molar ratio of 1:1, and 5% APS dosage. The polysiloxane coatings exhibit high thermal stability, however, which strongly depends on the coating composition.Highlights► Ambient-curable polysiloxane coatings were prepared with PTMS, MDMS and APS. ► Pro-hydrolysis step is essential for fabrication of thick crack-free coatings. ► Dependence of mechanical properties on coating composition and structure was studied. ► The coatings exhibit excellent mechanical properties and high thermal stability.
Co-reporter:Xiaolong Wang, Shuxue Zhou, Limin Wu
Materials Chemistry and Physics 2012 Volume 137(Issue 2) pp:644-651
Publication Date(Web):14 December 2012
DOI:10.1016/j.matchemphys.2012.09.070
Bifunctional Eu(BMDM)3@polysiloxane nanoparticles were prepared through reprecipitation–encapsulation methods using 1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione (BMDM) ligand and octyltrimethoxysilane (OTS) precursor and embedded into waterborne polyurethane (PU) coatings to fabricate transparent optical composite films. The photostability and thermostability of the nanoparticles in water and their ability to block UV and convert light when embedded in PU films were investigated. In comparison with the control Eu(BMDM)3 nanoparticles, the Eu(BMDM)3@polysiloxane nanoparticles, especially those prepared at a Eu(BMDM)3/OTS mole ratio of 1:2, exhibited far superior stability under storage conditions, UV irradiation, and heating. They also showed excellent UV-shielding and highly efficient light conversion properties because of the protective polysiloxane.Highlights► Eu(BMDM)3@polysiloxane nanoparticles were successfully prepared. ► The nanoparticles show excellent stability to storage, UV light, and heat. ► PU film with 0.3 wt% nanoparticles exhibited excellent UV shielding performance. ► The nanoparticles can be used as bifunctional additives for agriculture film.
Co-reporter:Xiaofeng Ding, Shuxue Zhou, Guangxin Gu and Limin Wu
Journal of Materials Chemistry A 2011 vol. 21(Issue 17) pp:6161-6164
Publication Date(Web):25 Mar 2011
DOI:10.1039/C0JM04546B
A long-term superhydrophobic self-cleaning coating was first fabricated by simply blending ambient-cured fluorinated polysiloxane binder with TiO2 nanoparticles. The obtained coating has excellent durability in various environments, and this method can be used for large-scale fabrication of self-cleaning coatings for practical applications.
Co-reporter:Xiaobing Chen;Bo You;Limin Wu
Journal of Sol-Gel Science and Technology 2011 Volume 58( Issue 2) pp:490-500
Publication Date(Web):2011 May
DOI:10.1007/s10971-011-2418-7
Ambient-curable polysiloxane coatings were prepared by hydrolysis and condensation of 3-methacryloxypropylmethyldimethoxysilane (MPDS) and methyltriethoxysilane (MTES) and subsequently mixing with 3-aminopropyltriethoxysilane (APS). The structures of the as-obtained polysiloxane oligomers as well as the dried polysiloxane coatings on tinplate substrates were analyzed by FTIR and 29Si NMR. The mechanical properties of the coatings were thoroughly examined at both macro-level and micro-level using a pendulum hardness rocker, an impact tester, and a nanoindentation/nanoscratch instrument. Effects of the molar ratio of MPDS/MTES, the dosage of aqueous ammonia solution, and the catalytic condition on the structure of polysiloxane oligomers as well as the structure and mechanical properties of the polysiloxane coatings were investigated. The dried coatings with thickness of 15–26 μm are highly elastic. The hardness (Koenig hardness and microhardness), impact resistance and scratch resistance are mainly dependent on the condensation degree of polysiloxane coatings rather than on the organic component of the coatings. A proper pre-hydrolysis process or more APS is benefit for enhancing the mechanical strength of the polysiloxane coatings. Polysiloxane coatings with high hardness and excellent scratch resistance can be prepared preferentially at low molar ratio of MPDS/MTES.
Co-reporter:Yiqing Hu, Guangxin Gu, Shuxue Zhou, Limin Wu
Polymer 2011 Volume 52(Issue 1) pp:122-129
Publication Date(Web):7 January 2011
DOI:10.1016/j.polymer.2010.11.020
Transparent PMMA/ZrO2 nanocomposites were prepared by in-situ bulk polymerization of methyl methacrylate (MMA)/ZrO2 dispersions that were firstly synthesized using nonaqueous synthesized ZrO2 nanocrystals and the function monomer, 2-hydroxyethyl methacrylate (HEMA), as the ligand. The dispersion behavior of ZrO2 nanoparticles in MMA, structure, mechanical and thermal properties of the PMMA/ZrO2 nanocomposites were investigated comprehensively. It was found that ZrO2 nanoparticles were well dispersed in MMA with HEMA ligand, but the MMA/ZrO2 dispersions easily destabilized in air as well as at elevated temperatures. The destabilization temperature of the dispersion is raised by increasing the molar ratio of HEMA/ZrO2 to match the bulk polymerization temperature. The PMMA/ZrO2 nanocomposites showed an interesting chemical structure (namely, highly cross-linked structure even at ZrO2 content as low as 0.8 wt% and hydrogen bonding interaction between polymer matrix and ZrO2 nanoparticles), with enhanced rigidity without loss of the toughness and improved thermal stability. The relationship between the structure and the properties of the PMMA/ZrO2 nanocomposites based on the HEMA coupling agent was discussed.
Co-reporter:Kun Xu, Shuxue Zhou, Limin Wu
Progress in Organic Coatings 2010 Volume 67(Issue 3) pp:302-310
Publication Date(Web):March 2010
DOI:10.1016/j.porgcoat.2009.10.029
Highly dispersible zirconia (ZrO2) nanocrystals were functionalized with γ-methacryloxypropyltrimethoxysilane (MPS) and dispersed in trimethylolpropane triacrylate (TMPTA), 1,6-hexandiol diacrylate (HDDA), tripropyleneglycol diacrylate (TPGDA) and aliphatic polyurethane oligomer (PU)/TPGDA mixtures, respectively. The dispersion behavior of MPS-functionalized ZrO2 (MPS-ZrO2) as well as its mechanical reinforcement for the PU/TPGDA matrixes was investigated. It was found that the dispersion of MPS-ZrO2 nanoparticles in UV-curable formulation strongly depends on the ZrO2 load, the grafting density of MPS, the composition of organic matrix and the type of monomer. A critical ZrO2 load beyond which phase separation of MPS-ZrO2 nanoparticles takes place exists for all cases. MPS-ZrO2 nanoparticles are more efficient to improve the pendulum hardness and scratch resistance of PU/TPGDA-based coatings that contains higher amount of TPGDA, being presumably due to quicker increase of the cross-linking density of the coatings. Additionally, a completely transparent TPGDA-based nanocomposite coating with ZrO2 load of as high as 60 wt.% can be obtained, and has absolutely high refractive index of 1.78.
Co-reporter:Hongbo Pang, Shuxue Zhou, Limin Wu, Min Chen, Guangxin Gu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 364(1–3) pp:42-48
Publication Date(Web):20 July 2010
DOI:10.1016/j.colsurfa.2010.04.026
Silicone oil microcapsules with thin silica shell (about 20 nm in thickness) were readily prepared by miniemulsion technique. The emulsion droplets consisting of tetraethoxysilane (TEOS), dimethylsilicone fluid and octadecyltrimethoxy (OTMS) were first stabilized in water with sodium laurylsulfonate/triton X-100 (SLS/OP-10) as surfactants and subsequently aged under stirring at pH value of 7.5, during which the silica shell formed through hydrolysis and condensation of TEOS/OTMS at the oil droplet/water interface. The obtained microcapsule latex had a solid content of as high as 17.6 wt% and very good long-term storage stability, which are absolutely benefit for practical application. The microcapsule size, around at 200 nm, was slightly changed with the mass ratios of SLS/OP-10 and TEOS/OTMS. The silicone oil microcapsules were directly embedded into waterborne coatings and showed a good slow-releasing property.
Co-reporter:Kaiqing Luo, Shuxue Zhou, Limin Wu, Bo You
Thin Solid Films 2010 Volume 518(Issue 23) pp:6804-6810
Publication Date(Web):30 September 2010
DOI:10.1016/j.tsf.2010.06.035
Highly-crystalline zirconia (ZrO2) nanoparticle was functionalized with 3-(N-aminoethyl) aminopropyltrimethoxysilane (AAPTMS) and dispersed in water at primary particle size level under basic condition (pH 13–14). The aqueous ZrO2 nanoparticle dispersion was cast on a polycarbonate substrate with 1,4-butanediol digylcidyl ether as a cross-linker. Nanoparticle films with as high as 81 wt.% of ZrO2 were obtained through heating the cast dispersion at 120 °C, which are highly transparent. The refractive index ranges from 1.70 to 1.77 at wavelength of 632 nm with the decrease of the amount of AAPTMS attached to ZrO2 nanoparticles. Nanoindentation tests show that the hardness of the film reaches 1.7 GPa. In addition, both punched tape abrasion and nanoscratch tests reveal that the films exhibit prominent scratch resistant performance.
Co-reporter:Kun Xu, Shuxue Zhou, Limin Wu
Progress in Organic Coatings 2009 Volume 65(Issue 2) pp:237-245
Publication Date(Web):June 2009
DOI:10.1016/j.porgcoat.2008.11.010
The photopolymerization kinetics of poly(urethane-acrylate)/zirconia (PUA/ZrO2) nanocomposite coatings were monitored on-line and in-real-time with microdielectrometry (DEA) in terms of logarithmic ion viscosity (log η). For comparison, real-time infrared spectroscopy (RTIR) was also employed to determine the evolution of CC bond conversion (C) with irradiation time (t). Coupling log η–t curves with C–t curves indicates that the relationship between log η and C for all the coatings with different formulations (i.e. the type of photoinitiator, ZrO2 content) and curing condition (i.e. irradiation intensity) can be correlated to one linear equation at conversion less than ∼85%. Moreover, DEA monitoring was longer time to reach polymerization equilibrium than RTIR for those cases with high limited conversion, suggesting that the former is more sensitive to CC bond conversion than RTIR at high conversion stage (C > ∼85%). DEA monitoring on the photopolymerization kinetics of PUA/ZrO2 coatings as a function of various parameters further demonstrates that DEA results are reliable and reasonable to conventional radical photopolymerization. It is believed that DEA technique will be useful not only on the optimization of curing condition but also for the formulation of UV-curable coatings.
Co-reporter:Bo You;Nangeng Wen;Yichen Cao;Limin Wu
Polymer International 2009 Volume 58( Issue 5) pp:519-529
Publication Date(Web):
DOI:10.1002/pi.2562
Abstract
BACKGROUND: Polyacrylate/silica nanocomposite latexes have been fabricated using blending methods with silica nanopowder, in situ polymerization with surface-functionalized silica nanoparticles or sol–gel processes with silica precursors. But these approaches have the disadvantages of limited silica load, poor emulsion stability or poor film-forming ability.
RESULTS: In this work, poly[styrene-co-(butyl acrylate)-co-(acrylic acid)] [P(St-BA-AA)]/silica nanocomposite latexes and their dried films were prepared by adding an acidic silica sol to the emulsion polymerization stage. Morphological and rheological characterization shows that the silica nanoparticles are not encapsulated within polymer latex particles, but interact partially with polymer latex particles via hydrogen bonds between the silanol groups and the COOH groups at the surface of the polymer particles. The dried nanocomposite films have a better UV-blocking ability than the pure polymer film, and retain their transparency even with a silica content up to 9.1 wt%. More interestingly, the hardness of the nanocomposite films increases markedly with increasing silica content, and the toughness of the films is not reduced at silica contents up to 33.3 wt%. An unexpected improvement of the solvent resistance of the nanocomposite films is also observed.
CONCLUSION: Highly stable P(St-BA-AA)/silica nanocomposite latexes can be prepared with a wide range of silica content using an acidic silica sol. The dried nanocomposite films of these latexes exhibit simultaneous improvement of hardness and toughness even at high silica load, and enhanced solvent resistance, presumably resulting from hydrogen bond interactions between polymer chains and silica particles as well as silica aggregate/particle networks. Copyright © 2009 Society of Chemical Industry
Co-reporter:Kaiqing Luo, Shuxue Zhou, Limin Wu
Thin Solid Films 2009 Volume 517(Issue 21) pp:5974-5980
Publication Date(Web):1 September 2009
DOI:10.1016/j.tsf.2009.03.162
UV-curable zirconia (ZrO2) nanoparticle coatings, prepared by dispersing highly-crystalline zirconia nanoparticles (4 nm) in tetrahydrofuran with the aid of 3-glycidoxypropyltrimethoxysilane (GPTMS) and following addition of a cationic photoinitiator, were cast on silicon wafers (or glass substrates) by dip-coating or spin-coating and photopolymerized to get transparent ZrO2 nanoparticle films. Ellipsometrical characterization indicates that the refractive index of the film changes from 1.63 to 1.77 at wavelength of 632 nm when the molar ratio of GPTMS-to-ZrO2 decreases from 0.30 to 0.15. Nano-indentation tests show that the films exhibit robust mechanical performance though they are not heat-treated.
Co-reporter:Yiqing Hu, Shuxue Zhou, Limin Wu
Polymer 2009 50(15) pp: 3609-3616
Publication Date(Web):
DOI:10.1016/j.polymer.2009.03.028
Co-reporter:Shuxue Zhou;Limin Wu
Macromolecular Chemistry and Physics 2008 Volume 209( Issue 11) pp:1170-1181
Publication Date(Web):
DOI:10.1002/macp.200800090
Co-reporter:Kaiqing Luo, Shuxue Zhou, Limin Wu and Guangxin Gu
Langmuir 2008 Volume 24(Issue 20) pp:11497-11505
Publication Date(Web):September 23, 2008
DOI:10.1021/la801943n
Zirconia (ZrO2) nanocrystals, synthesized from zirconium(IV) isopropoxide isopropanol complex and benzyl alcohol, were dispersed and functionalized in organic solvents using three kinds of bifunctional silane coupling agents (SCAs), 3-glycidoxypropyltrimethoxysilane (GPTMS), 3-aminopropyltriethoxysilane (APTES), and 3-isocyanatopropyltriethoxysilane (IPTES). Completely transparent ZrO2 dispersions were achieved in tetrahydrofuran (THF) with all three SCAs, in pyridine and toluene with APTES and IPTES, and in N,N-dimethylformamide with IPTES. Dynamic laser scattering (DLS) measurements and high-resolution transmission electron microscopical (HRTEM) observation indicated that the ZrO2 nanocrystals are dispersed on a primary particle size level. Fourier transform infrared spectroscopy, solid-state 13C- and 29Si NMR spectroscopy, and thermogravimetric analysis demonstrated that all three SCAs are chemically attached to the surface of the ZrO2 nanoparticles, however, in different bonding modes. Except for GPTMS/ZrO2/THF dispersion and IPTES/ZrO2/pyridine dispersion, all other transparent dispersions have poor long-term stability. The increasing polarity, due to high amount of APTES attached and high hydrolysis and condensation degree of the bonded APTES, and the aggregation, due to interparticle coupling via the bonded triethoxysilyl group, are the causes of the poor long-term stability for the ZrO2 dispersions with APTES and IPTES, respectively. Nevertheless, the APTES-functionalized ZrO2 precipitates can be deagglomerated in water to get a stable and transparent aqueous ZrO2 dispersion via addition of a little hydrochloric acid.
Co-reporter:Libang Feng;Hongxia Fang;Limin Wu;Bo You
Journal of Applied Polymer Science 2007 Volume 104(Issue 5) pp:3356-3366
Publication Date(Web):8 MAR 2007
DOI:10.1002/app.25940
Poly(methyl methyacrylate)-block-polydimethylsiloxane (PMMA-b-PDMS) copolymers with various compositions were synthesized with PDMS-containing macroazoinitiator (MAI), which was first prepared by a facile one-step method in our lab. Results from the characterizations of X-ray photoelectron spectroscopy (XPS), contact angle measurements, and atomic force microscopy (AFM) showed that the copolymer films took on a gradient of composition and more PDMS segments enriched at the film surfaces, which then resulted in the low surface free energy and little microphase separation at the film surfaces. By contrast, transmission electron microscopy (TEM) analysis demonstrated that distinct microphase separation occurred in bulk. Slight crosslinking of the block copolymers led to much steady morphology and more distinct microphase separation, in particularly for copolymers with low content of PDMS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Co-reporter:Baozhong Lin, Shuxue Zhou
Progress in Organic Coatings (May 2017) Volume 106() pp:145-154
Publication Date(Web):May 2017
DOI:10.1016/j.porgcoat.2017.02.008
Co-reporter:Kunlin Chen, Shuxue Zhou and Limin Wu
Chemical Communications 2014 - vol. 50(Issue 80) pp:NaN11894-11894
Publication Date(Web):2014/08/12
DOI:10.1039/C3CC49251F
A self-repairing superhydrophobic organic coating comprising polystyrene, fluorinated poly(methylsiloxane), fluorinated alkyl silane modified silica nanoparticles and photocatalytic titania nanoparticles shows self-repairing ability after mechanical damage, photocatalytic self-cleaning performance, and thus long-term outdoor durability.
Co-reporter:Yunjiao Gu, Jiahua Yang and Shuxue Zhou
Journal of Materials Chemistry A 2017 - vol. 5(Issue 22) pp:NaN10875-10875
Publication Date(Web):2017/04/03
DOI:10.1039/C7TA01499F
Oil contamination is problematic in subaqueous environments. It is difficult to prepare long-lasting textured superhydrophilic/underwater oil-repellent coatings without using a sophisticated method. Here, an ultra-facile and low-cost immersion-curing approach has been developed to generate superhydrophilic and underwater superoleophobic coatings from poly(vinyl alcohol) (PVA)/silica (SiO2) nanocomposites. During immersion curing, polymeric dissolution occurs simultaneously with crosslinking but occurs solely at the topmost layer, and helps to create enriched hierarchical surface micro-/nanostructures. Hence, superhydrophilicity is attainable for nanocomposite coatings with a filler percentage of only 15 wt%. Immersion-cured PVA/SiO2 nanocomposite coatings with 35 wt% silica have an excellent underwater superoleophobicity in terms of durability and ultra-low oil adhesion towards a variety of oils, including viscous crude oil. Because of its lower filler content and confined porous structure, this coating has a greater transparency compared with its conventional blend-curing underwater superoleophobic counterpart. Immersion-cured nanocomposite coatings display an excellent mechanical durability based on pencil hardness (3H) and sand-abrasion performance. The extra acrylic/melamine base-coat allows the underwater superoleophobic PVA/SiO2 coatings to be applied to diverse substrates, including glass, metals, and plastics, and renders them free from oil in aqueous environments.
Co-reporter:Xiaolong Wang, Shuxue Zhou and Limin Wu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 29) pp:NaN5758-5758
Publication Date(Web):2014/04/30
DOI:10.1039/C4TC00437J
Fe3+ doped Mg/Al layered double hydroxides (Mg/Al + Fe LDHs) were prepared by a facile solvothermal method. Incorporation of Fe3+ into Mg/Al LDHs can efficiently shift their UV-absorption to cover the entire UV range, allowing them to qualify as a candidate for blocking the whole UV light region (200–400 nm). The as-obtained Mg/Al + Fe LDHs possess intrinsic dispersibility in water, and, moreover, they can be dispersed in an organic solvent (xylene) after being sequentially washed with water/ethanol and then acetone. Accordingly, highly transparent and whole UV-blocking coatings were readily fabricated by incorporating Mg/Al + Fe LDHs into waterborne or solvent-based polysiloxane coatings, or merely using an aqueous Mg/Al + Fe LDH dispersion due to its self-supporting behavior. More importantly, the Mg/Al + Fe LDH-based coatings exhibited long-term UV-shielding performance even after accelerated weathering tests for as long as 800 h.
Co-reporter:Xiaolong Wang, Shuxue Zhou and Limin Wu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 45) pp:NaN7553-7553
Publication Date(Web):2013/09/26
DOI:10.1039/C3TC31479K
This paper presents a facile method for encapsulation of a SiO2 layer on the surfaces of ZnO quantum dots (ZnO QDs) to fabricate ZnO QD@SiO2 nanoparticles. Coating of a SiO2 layer can effectively improve the dispersion of ZnO QDs in an aqueous phase, insulate the photocatalytic activity of ZnO QDs and increase the photoluminescent quantum yield. When the as-obtained ZnO QD@SiO2 nanoparticles were introduced into acrylic latex, highly transparent, excellent UV-shielding and durable waterborne polymer coatings were easily fabricated. Moreover, the polymer coatings can convert UV into blue light effectively, which is beneficial for their application as agricultural films.
Co-reporter:Xiaofeng Ding, Shuxue Zhou, Guangxin Gu and Limin Wu
Journal of Materials Chemistry A 2011 - vol. 21(Issue 17) pp:NaN6164-6164
Publication Date(Web):2011/03/25
DOI:10.1039/C0JM04546B
A long-term superhydrophobic self-cleaning coating was first fabricated by simply blending ambient-cured fluorinated polysiloxane binder with TiO2 nanoparticles. The obtained coating has excellent durability in various environments, and this method can be used for large-scale fabrication of self-cleaning coatings for practical applications.
