The polyurethane/polyacrylate soap-free emulsion formation: effects of hydrophilic polyurethane

The vinyl group terminated water-borne polyurethanes (WPU) with different DMPA content were prepared. Subsequently the core-shell polyurethane/polyacrylate (PUA) composite emulsions were synthesized by soap-free emulsion copolymerization. The WPU as sole surfactant was used in copolymerization, and the lowest surface tension could be achieved to 38.8?mN m^?1. Furthermore, the final conversion of acrylic monomer was reached to 98% in the case of WPU reactive seed. The FTIR-ATR indirectly confirmed the core-shell structure of PUA, simultaneously combined with DSC results found that the compatibility of WPU and PA was enhanced by growing grafting efficiency. The TEM results further indicated that the amount of DMPA in WPU had a great significant role in polymerization and final morphology structure. The PUA composite particles changed from scattered structure, core-shell structure to multi-core structure with increasing DMPA content. Correspondingly, the reinforcing and toughening effects were also found in PUA films with the increase content of DMPA by tensile testing.     

Effect of Molecular Weight of WPU on the Heterogenic PUA Composite Latex Prepared by Soap-Free Emulsion Polymerization

Aqueous acrylic-polyurethane (PUA) composite emulsion was prepared by soap-free seeded emulsion copolymerization. Waterborne polyurethane (WPU) was used as the seeded emulsion and functioned as surfactant. The effect of molecular weight of WPU on the heterogenic was investigated. The molecular weight of WPU was controlled by varying the NCO/OH mole ratio. The GPC results confirmed that the molecular weight of WPU presented double distribution. And the molecular weight of WPU decreased with the increasing NCO/OH mole ratio. Surface tension test indicated that the molecular weight had little influence on the surface activity of WPU. However, after emulsion copolymerization of acrylic monomers, the morphology and properties of the PUA composite were impacted markedly by the molecular weight of WPU. With an increase in the NCO/OH mole ratio, the morphology of PUA composite latex changed from core-shell structures to fish bowl structure, and the mechanical properties of PUA films changed correspondingly.     

聚氨酯—聚丙烯酸树脂的合成及表征

讨论了在聚氨酯水分散体中进行丙烯酸酯共聚物乳液聚合的一些特征。研究表明,聚氨酯水分散体起着种子乳液的作用,发生了核－壳型事过程;复合乳液中聚氨酯链形成其壳,聚丙烯酸树脂分子链形成其核,二树脂的分子链相贯穿与缠结,形成了互穿网络结构。     

Synthesis of polyacrylate core-shell structure latex by radiation techniques

A series of poly(butyl acrylate-co-methyl methacrylate)/poly (ethyl acrylate-co-acrylic acid) interpenetrating polymer network (IPN) was synthesized in latex form by emulsion polymerization. The multiphase morphology of the latex particles was studied after two-stage polymerization by using transimission electron microscope (TEM), the result indicated that the morphology of the particles comprises gradient shell structure, cellular structure and core-shell structure. The change of morphology might stem from emulsion polymerization by radiation initiation or chemical initiation and the weight composition of poly(EA-co-MMA) seed latex which formed the core. By radiation techniques, we successfully synthesized poly( BA-co-MMA)/poly(EA-co-AA) latex of core-shell structure having (42-8)/(46-4) weight compositions. The PA core-shell structure latex applied to textile as a water proofing coating showed higher water-pressure and easier handling than that with PA homogeneous phase structure latex.     

Synthesis of polytetrafluoroethylene/polyacrylate core-shell nanoparticles via emulsifier-free seeded emulsion polymerization

Polytetrafluoroethylene (PTFE)/polyacrylate core-shell nanoparticles were produced via the emulsifier-free seeded emulsion polymerization of acrylate monomers with PTFE latex as seed. The monomer conversions under different synthesis parameters were monitored by a gravimetric method. The polymerization conditions for preparing PTFE/polyacrylate core-shell nanoparticles were surveyed and optimized. The chemical component of the PTFE/polyacrylate particles was confirmed by comparing the Fourier-transform infrared spectra of PTFE and PTFE/polyacrylate particles. The core-shell structure of the resulting PTFE/polyacrylate nanocomposite particles was investigated by transmission electron microscopy. The water contact angles of the films prepared from PTFE/polyacrylate nanocomposite particles showed that the films were hydrophilic, which confirmed that polyacrylate covered the surface of the PTFE particles. This kind of PTFE/polyacrylate core-shell nanoparticles might advance the compatibility of PTFE with other materials due to the covering of the polyacrylate shell on the surface of PTFE, which would make them promising in various fields.     

聚氨酯/聚丙烯酸酯复合乳液的研制进展

概述聚氨酯－聚丙烯酸酯复合乳液的制备方法。特别对聚氨酯－聚丙烯酸酯复合乳液共聚法作了较为系统的介绍和讨论。     

大分子不饱和单体法合成具有核壳结构的丙烯酸酯/聚氨酯乳液及表征

采用丙烯酸酯（AC）对水性聚氨酯（WPU）进行改性,合成了接枝型丙烯酸酯/聚氨酯(PUA)复合乳液。 随着共聚物中丙烯酸酯质量分数的增加,乳液外观由透明变为不透明,乳液粒径随之增大、分布变宽。 TEM显示,PUA乳胶粒子呈现清晰的核壳结构,且形态规整,粒径分布在60~120 nm之间。 FTIR测试表明,随着丙烯酸酯质量分数的增加,聚氨酯(PU)硬段氢键化作用先增强后减弱,硬段的有序度逐渐降低。 DSC分析表明,当AC的质量分数低于75%时,PU、聚丙烯酸酯(PA)两组分相容性较好,只出现一个玻璃化转变温度,并且随着PA质量分数的增加逐渐升高。 PA质量分数的增加,使胶膜的最大热失重速率从363 ℃提高至412 ℃,吸水率从11.3%降低至5.7%,弹性模量从16.4 MPa提高至47.6 MPa,拉伸强度从9.0 MPa提高至23.7 MPa,断裂伸长率从365%提高至408%,同时乳液的粘度下降,干燥时间变短,胶膜的附着力变好。     

聚氨酯/聚丙烯酸酯复合乳液粒子热力学平衡形态预测

以水性聚氨酯分散液为种子采用无皂乳液聚合新技术合成出了具有核壳结构的聚氨酯/聚丙烯酸酯（PU/PA）复合聚合物乳液。采用界面张力简化计算方法计算了聚合物与聚合物之间以及聚合物和水之间的界面张力,通过界面自由能变化最小的热力学判据对合成的复合乳液粒子的热力学平衡形态进行了预测。并利用透射电子显微镜观察和用接触角法测定的膜的表面极性对其进行了证实。结果表明：界面自由能变化的最小判据可以推广到PU/PA 体系,本文给出的界面张力的简化计算方法是可行的。     

Preparation of epoxy-acrylic latex based on bisphenol F epoxy resin

Bisphenol F based epoxy-acrylic latex with different amount of epoxy resin was successfully prepared by semi-continuous seeded emulsion polymerization. The resulting composite latexes had a narrow size distribution of about 105 nm in diameter. The DSC result showed that the epoxy resin and polyacrylate were grafting copolymerization. The FTIR spectra showed that the epoxy group had been introduced into the epoxy acrylic latex system, and the composite latex could be crosslinked with epoxy hardener at room temperature. The crosslinked composite latex film exhibited a high Tg compared to epoxy-acrylic latexes. The surface of the films with the epoxy resin was regular, and diffused into the polyacrylate phase in the epoxy-acrylic latexes films. Since the curing reactions occurred before latex particle coalescence stage, the surfaces of the cured epoxy-acrylate latex films had a number of interface particle. Compared with the acrylic latex, the thermal stability of the epoxy-acrylate latex was increased, and the stability of the cured film increased with increasing epoxy content.     

丙烯酸酯改性水性聚氨酯乳液的制备及性能研究

采用共聚的方法制备出丙烯酸酯改性的水性聚氨酯共聚乳液(PUA乳液),并对PUA乳液的制备方法和工艺、耐溶剂性、机械稳定性进行了初步的研究。结果表明,具有IPN结构的PUA乳液耐溶剂性、机械稳定性比水性PU有明显的提高。     

Preparation and characterization of emulsifier-free core–shell interpenetrating polymer network-fluorinated polyacrylate latex particles

The emulsifier-free core–shell interpenetrating polymer network (IPN) fluorinated polyacrylate latex particles with fluorine rich in shell were prepared by emulsifier-free seeded emulsion polymerization with water as the reaction medium. The fluorinated copolymer could be fixed on the particle surface due to the formation of interpenetrating polymer network. The resultant core–shell particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) analysis, Fourier transform infrared (FTIR) spectrometry, X-ray photoelectron spectroscopy (XPS) analysis and thermogravimetric analysis (TGA). The core–shell particles possessed very narrow monomodal particle size distributions. XPS analysis of the latex film displayed that perfluoroalkyl groups had the tendency to enrich at surface and there was a gradient concentration of fluorine in the structure of the latex film from the film–air interface to the film–glass interface. In addition, compared with the latex film of crosslinked polyacrylate prepared under the same condition, the emulsifier-free core–shell IPN-fluorinated polyacrylate latex film showed better thermal stability, higher contact angle and lower water uptake.     

Synthesis and characterization of poly (n-butyl acrylate)-poly (methyl methacrylate) latex interpenetrating polymer networks by radiation-induced seeded emulsion polymerization

A series of latex interpenetrating polymer networks (LIPNs) were prepared via a two-stage emulsion polymerization of methyl methacrylate (MMA) or mixture of MMA and n-butyl acrylate (n-BA) on crosslinked poly(n-butyl acrylate)(PBA) seed latex using ⁶⁰Co γ-ray radiation. The particles of resultant latex were produced with diameters between 150 and 250 nm. FTIR spectra identified the formation of crosslinked copolymers of PMMA or P(MMA-co-BA). Dynamic light scattering (DLS) showed that with increasing n-BA concentration in second-stage monomers, the particle size of LIPN increased. Transmission electron microscope(TEM) photographs showed that the morphology of resultant acrylate interpenetrating polymer network (IPN) latex varied from the distinct core-shell structure to homogenous particle structure with the increase of n-BA concentration, and the morphology was mainly controlled by the miscibility between crosslinked PBA seed and second-stage copolymers and polarity of P(MMA-co-BA)copolymers. In addition, differential scanning calorimeter (DSC) measurements indicated the existence of reinforced miscibility between PBA seed and P(MMA-co-BA)copolymer in prepared LIPNs.     

氯丁胶乳-聚甲基丙烯酸甲酯复合乳胶粒结构形态

以氯丁胶乳（Pa）为种子乳液,甲基丙烯酸甲酯（Pb）为第二单体,采用种子乳液聚合法,制备了氯丁胶乳-聚甲基丙烯酸甲酯复合乳胶粒。 热力学分析表明,当Pb的体积分数Φb＜0.69时,可同时形成Pa-Pb型正核-壳和（Pa＋Pb）分离型乳胶粒,当Φb＞0.69时,形成Pb-Pa型翻转型核壳结构乳胶粒,并伴有Pa-Pb型正核-壳结构乳胶粒的形成。 动力学分析表明,引发剂类型、第二单体的加入方式、种子乳胶粒的交联、单体/聚合物质量比是影响乳胶粒形态的主要因素。 采用水溶性引发剂过二硫酸钾（KPS）,以饥饿态方式加入单体,氯丁胶乳 聚甲基丙烯酸甲酯(PCR-PMMA)复合乳胶粒呈现正核-壳结构,以充溢态方式加入单体则不能形成明显的核-壳结构;而以油溶性偶氮二异丁腈（AIBN）为引发剂时,单体无论以充溢态方式加入还是饥饿态加入均倾向于形成翻转核-壳型粒子。 在种子乳胶粒中加入一定量交联剂二缩三乙二醇二甲基丙烯酸酯,有利于形成明显的正核壳结构。 以饥饿态进料,KPS为引发剂时,随着单体用量增加,壳层变厚,仍呈正核-壳结构,与热力学分析结果相吻合;以AIBN为引发剂时,随着单体用量增加,PCR-PMMA复合乳胶粒逐渐由翻转核壳型结构变为互穿结构。     

Polyurethane–polyacrylate interpenetrating polymer networks. I

Two-component topologically interpenetrating polymer networks (IPN) of the SIN type (simultaneous interpenetrating networks) composed of a melamine-cured polyacrylate and five different polyether-based polyurethanes were made. The linear polymers and prepolymers were combined in solution, together with the necessary crosslinking agents and catalysts; films were cast, chain-extended, and crosslinked in situ. Infrared spectroscopy indicated that little or no reaction between the different networks occurred. In all cases, except for one IPN which was made from a very highly crosslinked polyurethane, maxima in tensile strength, significantly higher than the tensile strengths of the components, occurred. This was explained by an increase in crosslink density resulting from interpenetration. Some enhancement in other physical properties (impact strength and thermal resistance) was also noted.     

乳液互穿网络型丙烯酸酯类热塑性弹性体的研究

以xPEA/xPSt和xPEA/xPSAN体系为例,考察多步种子乳液聚合法合成乳液互穿网络聚合物(LIPN)的合成条件,通过TEM观察了乳粒形态结构.xPEA在较低的交联度下,xPEA/xPSt(质量比75/25)和xPEA/xPSAN乳粒为一壳多核的反核壳结构,但是xPEA在较高的交联度下则生成核壳结构乳粒.DSC分析结果表明,在反核壳的乳粒中两种聚合物之间形成互穿网络(IPN)结构.考察了xPEA/xPSt体系LIPN型热塑性弹性体(TPE)的力学性能与互穿网络之间的关系及微相重组在材料力学性能中的作用.xPEA中TEGDA的质量分数为0.5%,xPSt中DVB的质量分数为0.15%时,材料性能最佳.     

聚氨酯脲-丙烯酸酯水分散液的粒径及形态研究

研究了羧基含量、异氰酸酯指数（［ － ＮＣＯ］／［ － ＯＨ］） 、聚氨酯脲与聚丙烯酸酯组成比（ＰＵＵ／ＰＡ） 以及一系列制备工艺因素对聚氨酯脲—丙烯酸酯（ＰＵＡ） 水分散液粒子尺寸及形态的影响。结果表明：羧基含量和ＰＵＵ／ＰＡ 组成比增大或异氰酸酯指数减小都会导致分散液粒径减小;ＰＵＡ 中ＰＡ 含量越大,ＰＵＡ 水分散液粒子形态越不规整;工艺因素如搅拌强度、升温速率等对ＰＵＡ 水分散液粒子尺寸及形态的影响不符合传统乳液聚合的规律。     

氟含量对含氟丙烯酸酯共混乳胶膜梯度结构和表面性能的影响

首先将制备出的平均粒径较小的含氟丙烯酸酯均聚物乳液与平均粒径较大的纯丙烯酸酯共聚物乳液按不同的比例( 1/9,2/8,3/7,4/6,5/5)共混,接着将各共混乳液在室温下(20℃)玻璃基材上干燥后,于110℃/210℃下热处理一段时间.运用接触角法,XPS、AFM、SEM-EDX等详细研究了共混乳胶膜中含氟组分含量对...     

有机硅改性磺酸型聚氨酯/丙烯酸酯复合乳液的制备

将磺酸型聚酯多元醇、异佛尔酮二异氰酸酯（IPDI)和三羟甲基丙烷(TMP)在无有机溶剂参与的情况下进行预缩聚,以硅烷偶联剂γ-氨丙基三乙氧基硅烷（KH550）作为改性剂,加入双官能团单体甲基丙烯酸-β-羟乙酯(HEMA),得到含乙烯基和有机硅封端的聚氨酯作为种子乳液,然后与甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)混合单体共聚,合成了有机硅改性磺酸型聚氨酯/丙烯酸酯复合乳液。 红外光谱的表征确定了有机硅改性磺酸型聚氨酯/丙烯酸酯复合乳液的化学结构;透射电子显微镜观察证实了此复合乳液具有明显的核壳结构;热重分析表明,经有机硅和丙烯酸酯改性后,胶膜的最大热失重温度提高了20 ℃,X射线衍射分析表明胶膜的结晶度降低,有利于提高膜的韧性。 力学性能测试及吸水率测试结果表明,当有机硅含量为1.9%时,胶膜的拉伸强度最高达到25.03 MPa,断裂伸长率为328%,此时膜的吸水率最低。     

Semi-continuous emulsion polymerization of styrene in the presence of poly(methyl methacrylate) seed particles. Polymerization conditions giving core-shell particles

This work reports the morphology of two-phase latex particles prepared by semi-continuous seed emulsion polymerization of styrene in the presence of polar poly(methyl methacrylate), PMMA, seed particles, using different conditions of non-polar styrene feed rate, rate of initiation, seed particle concentration and temperature of polymerization.The expected latex particle morphology at thermodynamic equilibrium is an inverted core-shell structure where the non-polar polystyrene would form the core. However, depending on the set of process conditions used the morphology of the resulting two-phase particles varied from that of a pure core-shell structure, over intermediate structures in which a shell of PS surrounded a PMMA core containing an increasing number of PS phase domains, to a structure in which the entire PS phase was present as discrete PS phase domain, more or less evenly distributed in a matrix of PMMA.By the use of a caloirimetric reactor system the monomer concentration in the particles during the different polymerization experiments could be calculated by comparing the integral of the polymerization rate curve with the integral of the monomer feed rate. A comparison between particle morphology and the calculated concentration of plasticizing monomer in the polymerizing particles strongly suggested that the diffusivity of the entering oligo radicals determined by the difference between polymerization temperature and the glass transition temperature of the monomer-swollen core polymer is a key factor determining the morphology of two-phase particles prepared by semi-continuous seed emulsion polymerization.Two-phase particles with a true core-shell structure were obtained in experiments where the estimated glass transition temperature of the PMMA phase was only a few degrees below the polymerization temperature. The results show that such particles can be obtained under conditions of high as well as low styrene feed rates, provided that the rate of initiation is properly adjusted.     

The Effect of Weight Fraction of H-PDMS on the Latex Membrane and the Stability of Composite Emulsion of H-PDMS/Acrylate

High hydrogen-containing polymethylsiloxane(H-PDMS)/polyacrylate composite emulsion was synthesized by a drop-adding method for monomer emulsion. The effects of weight fraction of H-PDMS on the stability of composite emulsion, water resistance and heat-aging resistance of the latex membrane have been investigated. The TEM demonstrated that latex particles are a core-shell structure. By analyzing the spectrums of FTIR and ¹H-NMR, it can be indicated that H-PDMS had reacted with acrylate monomer resulting chemical bond formation. The core-shell structure and chemical bond play an important role to restrain phase separation of composite emulsion and enhance the stability of the emulsion. By analyzing the surface tension, apparent viscosity and morphological structure, the results showed that the stable composite emulsion system can be obtained in which the average latex particle size was smaller than 90 nm when weight fraction of H-PDMS is below 16% (based on the weight of acrylate monomer), the stable emulsion system can be obtained in which the average latex particle size becomes larger than 90 nm when the weight fraction of H-PDMS is above 20% of the acrylate monomer. The DSC demonstrated that the T_g of pure polyacrylate is 49°C, and there is only one T_g (35°C) when the weight fraction of H-PDMS is 13%, but there are two T_g (15°C and 25°C) when the weight fraction of H-PDMS is 16%. In addition, the water resistance and heat-aging resistance of composite latex membrane enhanced gradually with the increase of amount of H-PDMS.