Effect of storage time on the characteristics of a waterborne polyurethane/tetraethoxysilane mixture and the properties of prepared films

Waterborne polyurethane (WPU) is one of the most important resins. The properties of WPU can be modified by introducing inorganic components. Tetraethoxysilane (TEOS) is a precursor for preparing inorganic polymers and can be used to prepare WPU/silica hybrids. In this study, WPU dispersion was synthesized by reacting polytetramethylene ether glycol and dimethylolpropionic acid with isophorone diisocyanate, followed by chain extension with ethylenediamine. After mixing WPU with TEOS, the mixture was sealed and stored at room temperature for different lengths of times. The influence of time on the characteristics of the WPU/TEOS mixture and the properties of films were investigated. The results showed that the viscosity, surface tension and average particle size of the mixture increased with prolonged storage time. ²⁹Si-NMR analysis indicated that the structure of silica exists in the WPU film. DSC, DMA and TGA results showed that WPU/silica films made from the mixture have less thermal activity, higher storage modulus, lower damping peak heights and better heat resistance after relatively long storage times.     

水性聚氨酯/聚甲基丙烯酸甲酯杂化乳液的合成

用异佛尔酮二异氰酸酯(IPDI)、聚丙二醇(PPG)和二羟甲丙酸(DMPA)合成了水性聚氨酯分散体(WPU),讨论了PPG摩尔质量,NCO/OH及PPG/DMPA比例对WPU乳液和涂膜性能的影响。以WPU为种子与甲基丙烯酸甲酯进行乳液聚合制备杂化乳液,研究了不同PU/PMMA物质的量比例对杂化乳液及涂膜性能的影响,并采用TEM对WPU及杂化乳液粒子进行了表征。结果表明,在以PPG1000为原料,NCO与OH物质的量比为1.4∶1,PPG与DMPA物质的量比为1∶0.8条件下制备的WPU杂化乳液,随着PMMA比例增加,杂化乳液的稳定性和成膜性变差,聚合物膜断裂伸长率降低,但铅笔硬度、耐水性及耐乙醇性均得到了改善。     

无卤阻燃硅溶胶改性水性聚氨酯的研究

以聚醚(N -210)、异佛尔酮二异氰酸酯(IPDI)为基本单体,一缩二乙二醇(EX)为扩链剂,二羟甲基丙酸( DMPA)为亲水扩链剂,制备出固含量为30％的水性聚氨酯(WPU)乳液.采用机械分散的方式将纳米硅溶胶按计量加入到WPU乳液中,得到一系列硅溶胶改性的WPU乳液.研究表明,硅溶胶在WPU中分散得比较均匀,硅溶...     

Preparation and characteristics of a waterborne preventive stain coating material with organic-inorganic composites

With the goal of developing a waterborne coating material that prevents staining, organic-inorganic composites prepared from colloidal silica and two types of acrylic resin emulsions were investigated as exterior coatings. conventional acrylic resin emulsion and organic silane hybridized acrylic resin emulsion prepared by emulsion polymerization were mixed with colloidal silica to form organic-inorganic comiposite films. The addition of colloidal silica to emulsions yielded films with higher hydrophilicities, as indicated by lower water contact angles for these films in comparison to films without colloidal silica. The water contact angles of organic silane hybridized acrylic resin emulsion/colloidal silica films were lower than those of acrylic resin emulsion/colloidal silica films. Composite films containing colloidal silica particles smaller than 100 nm in diameter showed high hydrophilicities. Observations of the dispersed state of colloidal silicaparticles in organic-inorganic composite films by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that colloidal silica particles were densely aggregated on the film surface. Outdoor exposure tests of the coating materials prepared from organic silane hybridized acrylic resin and colloidal silica particles with diameters of 7.5 nm showed excellent stain resistance.     

水性聚氨酯/硅溶胶复合涂层的制备与性能

将水性聚氨酯乳液与硅溶胶共混,制备了水性聚氨酯/硅溶胶复合乳液。采用TEM、激光粒度分析仪、流变仪、ATR-FTIR、TG对复合乳液及其涂膜进行表征,探讨了硅溶胶用量对复合涂膜性能的影响。ATR-FTIR分析表明,聚氨酯分子和硅溶胶之间可以形成氢键,但不存在化学键结合;TEM、激光粒度分析测试表明,硅溶胶质量分数的增加,使复合乳液粒子粒径增大,粒度分布变宽,当硅溶胶质量分数20%后,乳胶粒子间易发生团聚;流变分析发现,加入硅溶胶后,乳液的表观黏度(ηa)增大,假塑性增强。性能测试结果表明,硅溶胶质量分数20%时,复合乳液具有好的储存稳定性,复合涂膜表现出很好的热稳定性,48 h吸水率仅为18.94%,同时表现出很好的耐溶剂性能,拉伸强度达到28.98 MPa,铅笔硬度达2H,附着力0级。     

Preparation and properties of Waterborne polyurethane/nanosilica composites: A diol as extender with triethoxysilane group

Waterborne polyurethane (WPU) was prepared from toluene diisocyanate, polypropylene glycol, 2,2‐bis(hydroxymethyl)propionic acid and a diol containing triethoxysilane group as the chain extender which was synthesized via Michael addition between 3‐triethoxysilylpropylamine and 2‐hydroxyethylacrylate. Different amounts of nanosilica were incorporated into the WPU to prepare WPU/nanosilica composites. The results showed that the particle size of the emulsions increased and their viscosity decreased first and then increased with increasing the amount of nanosilica. Incorporation of nanosilica into WPU enhanced the water contact angle and thermal stability of the composites films, meanwhile, their tensile strength and hardness increased first and then decreased. However, increasing the amount of nanosilica resulted in reduction in the elongation at break of the films. It suggested that nanosilca was anchored into the side chain of WPU due to the condensation process between the triethoxysilane group in the side chain of WPU molecular and the silanols group on the surface of nanosilica. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40526.     

聚氨酯-聚丙烯酸酯复合胶乳的制备及其性能研究

通过丙酮工艺法,分别制备了含有羧基作为内乳化剂的乙二胺扩链型水性聚氨酯(EDAWPU)和甲基丙烯酸β羟乙酯(HEMA)封端的水性聚氨酯(VLWPU)。为了改善水性聚氨酯(WPU)膜的性能,采用无皂乳液法制备了未交联型和交联型水性聚氨酯/聚丙烯酸酯复合乳液(UCPUA和CPUA)。通过红外对EDAWPU和VLWPU的化学结构进行了确认。使用TEM发现CPUA复合乳胶的形貌是以聚丙烯酸酯为核,聚氨酯为壳的核/壳结构。CPUA和UCPUA的分子量分别为310934和86522。从DSC曲线中能观察到CPUA膜的玻璃化转变温度相对较高。在CPUA膜中,通过交联CPUA的拉伸强度也得到增加。所以结果显示CPUA复合乳胶在硬度,附着力,柔韧性,光泽度和耐水性等方面均显示出了优异的性能。     

Polydicyclopentadiene Reinforced with Grafted Silica Nanoparticles

Polydicyclopentadiene (PDCPD) nanocomposites reinforced with nanoscale silica were prepared by an in-situ polymerization technique in simulating reaction injection molding system. The nanoscale silica particles were treated with toluene diisocynate (TDI) and 5-norbornene-2-carboxylic acid (NCA). The analysis of IR, TGA and dispersion test on the modified nanoscale silica showed the success of surface modification. The incorporation of nanoscale silica of low content had an positive effect on hardness and bending strength of the PDCPD matrix. The wear resistance of PDCPD/ silica nanocomposite is significantly improved in comparison with neat PDCPD, and the SEM micrographs of the worn surface revealed their wear mechanisms.     

The structure and properties of acrylic‐polyurethane hybrid emulsions and comparison with physical blends

Aqueous acrylic‐polyurethane hybrid emulsions were prepared by semibatch emulsion polymerization of a mixture of acrylic monomers (butyl acrylate, methyl methacrylate, and acrylic acid) in the presence of polyurethane dispersion. Equivalent physical blends were prepared by mixing acrylic emulsion and polyurethane dispersion. The weight ratio between acrylic and polyurethane components varied to obtain different emulsion properties, microphase structure, and mechanical film properties of hybrid emulsions and physical blends. Particle size and molecular mass measurements, scanning electron microscopy, glass transition temperature, and rheological measurements performed characterization of the latex system. The mechanical properties were investigated by measuring tensile strength and Koenig hardness of dried films. The experimental results indicate better acrylic‐polyurethane compatibility in hybrid emulsions than in physical blends, resulting in improved chemical and mechanical properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 67–80, 2000     

Maleopimaric acid‐modified two‐component waterborne polyurethane for coating applications

Maleopimaric acid (MPA), an important rosin derivative, was used to partially substitute isophthalic acid for the preparation of an anionic polyol (MPP) dispersion. The MPP dispersion was then applied to prepare a novel maleopimaric acid‐modified two‐component waterborne polyurethane (MPP‐2K‐WPU). The influences of NCO:OH molar ratio on the thermal properties, water absorption, surface free energy, and application properties of MPP‐2K‐WPU films were investigated. With increasing NCO:OH molar ratio, the thermal stability, pencil hardness, and ethanol resistance of MPP‐2K‐WPU films were improved, but the water resistance was enhanced firstly and then weakened. The surface free energy of MPP‐2K‐WPU films mainly depended on the dispersion interaction which was related to the structure of macromolecules. In addition, compared with the control sample of PP‐2K‐WPU(1.5:1) film, the MPP‐2K‐WPU(1.5:1) film exhibited improved thermal stability, water resistance, gloss, pencil hardness, and ethanol resistance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43292.     

纳米二氧化硅水溶胶改性UWPU的研究

通过丙酮法合成光固化水性聚氨酯丙烯酸酯预聚体,用三乙胺中和后在乳化过程中原位引入纳米二氧化硅水溶胶(Wv33、R900、R301)制备二氧化硅/光固化水性聚氨酯(SiO2/UWPU)纳米复合乳液,并进一步通过紫外光固化制备了SiO2/UWPU复合膜。通过电子扫描显微镜(SEM)和电子拉力机研究了不同纳米二氧化硅水溶胶对UWPU/SiO2复合膜的微观结构和力学性能的影响。SEM分析表明表面有机改性的pH值接近中性的硅溶胶(Wv33)较pH为酸性或碱性的硅溶胶在聚氨酯基体中有较好的分散性;应力-应变曲线分析表明Wv33能有效实现对复合膜的增强,即提高了复合膜的储存模量、拉伸强度和邵A硬度。     

Improvement of Hardness and Wear Resistance of Glass Fiber-Reinforced Epoxy Composites by the Incorporation of Silica/Carbon Hybrid Nanofillers

The tribological performance of hybrid composite (epoxy reinforced with woven, nonwoven tissue glass fibers, silica and carbon black nanoparticles) was investigated. Two methods were used to ensure good dispersion of nanoparticles in epoxy resin which were ultrasonic processor and magnetic stirrer. The effect of silica and/or carbon black nanoparticle content on microindentation hardness and wear properties of the neat glass fiber-reinforced epoxy composites was investigated. The results from the wear test indicated that, under all applied loads, incorporation of silica and carbon black nanoparticles either single or combined significantly improved the wear resistance of neat glass fiber reinforced epoxy. A significant increase in hardness of the hybrid nanocomposite laminates was achieved. Analysis of variance was developed to study the optimal wear testing parameters on composite samples. The most significant parameter is the time, followed by nanoparticle (silica and carbon black) content.     

不同聚醚二元醇软段对光固化水性聚氨酯乳液性能的影响

以不同聚醚二元醇、异佛尔酮二异氰酸酯、2,2-双羟甲基丙酸、甲基丙烯酸-2-羟基乙酯为主要原料,通过丙酮法合成光固化水性聚氨酯(WPU)乳液,讨论了不同聚醚软段对光固化WPU乳液性能的影响.结果表明,由聚四氢呋喃醚二元醇PTMG1000和PTMG2000制备的光固化WPU乳液具有较小的粒径和粘度,其交联后的膜具有较高储...     

Synthesis and characterization of nanosilica/waterborne polyurethane end‐capped by alkoxysilane via a sol‐gel process

A novel method was used to synthesis nanosilica/waterborne polyurethane (WPU) hybrids by in situ hydrolysis and condensation of tetraethyl orthosilicate (TEOS) and/or 3‐aminopropyltriethoxylsilane bonding at the end of the WPU molecular chain. The hybrid was characterized by scanning electron microscopy, energy dispersive spectroscopy (EDS), transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS). The results showed that the nanosilica/WPU hybrids with well‐dispersed nanosilica particles were synthesized, in which the particles had typical diameters of about 50 nm. In addition, XPS and FTIR analyses demonstrated that chemical interaction occurred between WPU and silica. The effects of TEOS on surface wettability, water resistance, mechanical strength, and thermal properties of the hybrid were also evaluated by contact angle measurements, water absorption tests, mechanical tests, and differential scanning calorimetry, respectively. An increase in advancing contact angles, water resistance, and tensile strength, as well as decrease in elongation at break and glass transition temperature, were obtained with the addition of TEOS. Water absorption decreased from 17.3 to 5.5%. The tensile strength increased to a maximum of 29.7 MPa, an increase of about 34%. Elongations at break of the hybrids decreased 191%. These results were attributed to the effects of the nanosilica and the chemical interaction between WPU and silica. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Dual‐curable unsaturated polyester inorganic/organic hybrid films

An unsaturated polyester, based on maleic anhydride, 1,6‐hexanediol, and trimethylol propane, was formulated with tetraethylorthosilicate (TEOS) oligomers and a coupling agent to prepare inorganic/organic hybrid films. TEOS oligomers were prepared through the hydrolysis and condensation of TEOS with water, and 3‐(triethoxysilyl)propylisocyanate was used as the coupling agent between the organic and inorganic phases. The hybrid materials were cured by moisture via sol–gel chemistry and by the UV curing of unsaturated polyesters. To compare the properties of the moisture‐cured inorganic/organic hybrid films, a conventional 2K polyurethane system was also prepared. The tensile, adhesion, abrasion, and fracture toughness properties were investigated as functions of the coupling agent and relative amount of UV cure versus thermal cure. Although no difference could be observed in the tensile properties, the abrasion resistance, fracture toughness, and adhesion were enhanced by the incorporation of TEOS oligomers into polyurethane films. Also, the abrasion resistance, fracture toughness, and tensile properties were increased with both moisture and UV exposure. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 115–126, 2006     

One-pot fabrication of fluoride-silica@silica raspberry-like nanoparticles for superhydrophobic coating

A facile and effective method to fabricate raspberry-like nanoparticles is reported in a one-pot reaction. This method consists of two steps: preparation of silica nanoparticle precursors dispersion via the Stober process and growth of the tiny functional fluoride-silica nanoparticles on the surface of silica nanoparticle precursors via the hydrolysis-condensation reaction of tetraethoxysilane (TEOS) and 1H,1H,2H,2H-Perfluorodecyl triethoxysilane (HDFTES). The obtained raspberry-like nanoparticle dispersion could be spray coated onto different substrates directly with the water contact angle greater than 150° and water roll-off angle less than 4°. And the prepared coatings maintained water resistance after water jetting, sand abrasion. This method can be an effective strategy for fabricating superhydrophobic surfaces for practical industrial applications.     

水性聚氨酯荧光增白材料的合成及其性能研究

荧光增白剂可吸收不可见的紫外光,并且将紫外光转变为可见的蓝色或蓝紫色光发射出来;由于蓝色和黄色互为补色,消除了物质中的黄色部分,从而达到了增白效果。因此,采用荧光增白剂合成的水性聚氨酯(WPU)增白材料,用于涂料和织物上,可初步解决芳香族WPU的耐黄变问题。研究了乳液pH值、荧光增白剂的用量及其添加方式对WPU增白效果的影响,并通过透射电镜(TEM)观察增白剂在WPU中的分散情况。实验结果表明,WPU乳液及其胶膜的蓝光效果随着荧光增白剂用量的增加呈先增后降的趋势,当w(荧光增白剂)=0.008%时为最佳;当pH=7～9时,荧光增白剂在WPU中的分散稳定性和增白效果都较好;荧光增白剂的两种添加方式对其在WPU乳液及其胶膜中的分散稳定性和增白效果的影响不明显。     

WPU/CB/GO nanocomposites: in situ polymerization preparation,thermal, and anticorrosion performance evaluation

In this paper, composite fillers including graphene oxide and carbon black had been applied to modify pure waterborne polyurethane (WPU) and a new nanocomposite was prepared by in situ polymerization, whose structure was characterized by Fourier transform infrared spectroscopy that demonstrated interfacial interactions existing between the filler particles and the hard segments of WPU chains. Meanwhile, thermal properties of prepared nanocomposites were enhanced after adding composite fillers as shown in the results of thermogravimetric analysis and differential scanning calorimetry curves, which could be explained by several factors including strong interface interaction between organic phase and inorganic phase verified by infrared spectra and scanning electron microscopy as well as transmission electron microscopy, good dispersion and barrier effect of the composite fillers, reinforced crosslinking density of the system. Additionally, the contact angle and anticorrosion performance of the nanocomposite films were heightened after adding fillers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48716.     

Synthesis and properties of novel water‐dispersible polyisocyanates

A series of novel water‐dispersible polyisocyanates (WDPs) were synthesized with hexamethylene diisocyanate isoxyanurates (HDI trimer), dimethylol butanoic acid (DMBA), polyethylene glycol monomethyl ether (MPEG‐600) and 1,4‐cyclohexanedimethanol (CHDM) as materials. Two‐component waterborne polyurethane (2K‐WPU) films based on WDPs were prepared and characterized by ultraviolet‐visible spectrophotometer, thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), and surface contact angle measurement. The effects of molar ratios of DMBA/MPEG and CHDM/MPEG and their amounts on properties of WDPs including the water dispersibility, storage stability, films hardness, and water resistance were also investigated. The results showed that the introduction of CHDM could efficiently improve the storage stability, the hardness and water resistance of 2K‐WPU films due to the rigid cyclic structure and hydrophobicity property of CHDM. It was found that WDPs had excellent storage stability, and the 2K‐WPU displayed short tack‐free times, high hardness, good water resistance, excellent surface appearance and gloss with 3:7:3 of the molar ratio of DMBA/MPEG/CHDM. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44735.     

Effect of nanosilica content on properties of polyurethane/silica hybrid emulsion and its films

Polyurethane/silica hybrid emulsion (PUSi) was synthesized by the reaction of isophorone isocyanate, polyether polyol, hydrophilic nanosilica (A200), dimethylol propionic acid, trimethylol propane, and 3‐aminopropyltriethoxysilane (KH550). The films of the waterborne polyurethane (WPU) were prepared. The structure of the polyurethane was characterized by Fourier transform infrared spectrometer (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). The particle size distribution and morphology of emulsion were examined. Influence of nanosilica content on the mechanical properties and solvent absorption of the cast films were also measured quantificationally. FTIR indicates that  NH₂ of KH550 reacted with  NCO of polyurethane. TG analysis indicates that nanosilica can improve thermal stability of polyurethane. There is no clear effect of nanosilica on the glass transition of soft segments. It was found that greater mechanical properties of WPU were obtained when chemical networks were formed by sol‐gel process. As the nanosilica content increases, water absorption and ethanol absorption decreased. The particle size increases with increase of A200 content. PUSi hybrid emulsions are endowed with pseudoplasticity. The apparent viscosity of emulsions increased and then decreased with addition of A200. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011