核壳结构聚氯乙烯-丙烯酸酯共聚树脂乳胶的性能研究

研究了两类具有不同核壳结构的聚氯乙烯–丙烯酸酯(PVC-ACM)共聚树脂乳胶。通过核磁共振谱仪和透射电子显微镜分别分析了共聚树脂的化学结构与粒子的形貌,按照国家标准或行业标准考察了两类乳胶作为建筑及工业涂料用乳胶的主要性能。结果表明,两类共聚树脂粒子均能观察到核壳结构,其中PVC/ACM共聚树脂粒子的核壳结构更为明显;两类乳胶的主要性能基本满足国家标准或行业标准的要求,而PVC/ACM乳胶更适合应用于建筑涂料领域。     

环氧树脂改性核壳乳胶粒子的制备

采用预乳化-半连续种子乳液聚合工艺制备了环氧树脂改性聚丙烯酸丁酯/(聚甲基丙烯酸甲酯-衣康酸)(PBA/P(MMA-ITA-DGEBA))核壳乳胶粒子。采用激光粒度仪、傅立叶变换红外光谱(FTIR)、差示扫描量热仪(DSC)、透射电子显微镜(TEM)等方法对核壳乳胶粒子进行了表征,实验结果表明:PBA/P(MMA-ITA-DGEBA)乳胶粒子确为核壳结构,双酚A型环氧树脂已经被成功接枝到核壳乳胶粒子上,由于ITA、DGEBA链段的存在,导致壳层PMMA玻璃化转变温度的(Tg)升高。     

核壳型复合高分子乳液乳胶粒子形态学

系统阐述了核壳型复合高分子乳液乳胶粒子形态方面的研究进展。探讨了单体亲水性、聚合工艺、加料方式、引发剂、聚合场所的粘度、种子交联度、聚合温度及反应体系pH值等对乳胶粒子形态的影响。介绍了热力学研究的概况 ,并通过计算界面自由能变化最小来控制和预测粒子的形态。讨论了粒子核壳结构对乳液性能的影响 ,如最低成膜温度 ,核壳结构在热处理后机械、光学性能的变化。总结了用来表征乳胶粒子核壳结构常用的手段 ,包括透射电镜法 (TEM) ,扫描电镜法(SEM) ,示差量热扫描法 (DSC) ,最低成膜温度法 (MFT)以及通过测定两阶段聚合物中羧基的分布来确定粒子的形态等     

PBA/P(MMA-ITA)核壳胶乳粒子的合成

采用种子乳液聚合方法合成了聚丙烯酸丁酯(PBA)/聚(甲基丙烯酸甲酯-衣康酸)[P(MMA-ITA)]核壳乳胶粒子,并用透射电子显微镜、傅里叶变换红外光谱仪、差示扫描量热仪及非水酸碱滴定等对其进行了表征.结果表明:核壳乳胶粒子平均粒径为330 nm,其中,PBA核平均粒径为290 nm;通过接枝共聚物P(MMA-ITA)实现了核壳间的化学键连接.     

PBA-P(MMA-DMA)核壳乳胶粒子的制备

采用预乳化半连续种子乳液聚合方法制备了一种新型的表层含氨基的聚甲基丙烯酸丁酯(PBA)-聚(甲基丙烯酸甲酯-甲基丙烯酸二甲氨基乙酯)[P(MMA-DMA)]核壳乳胶粒子,并通过激光粒径分析仪、透射电子显微镜、X射线光电子能谱仪和元素分析仪等对其进行表征。结果表明:PBA-P(MMA-DMA)乳胶粒子为核壳结构,PBA核芯和PBA-P(MMA-DMA)核壳乳胶粒子的平均粒径分别为270,340 nm;PBA-P(MMA-DMA)核壳乳胶粒子的壳层确实含有甲基丙烯酸二甲氨基乙酯(DMA),当DMA用量为甲基丙烯酸甲酯质量的10.0%时,PBAP(MMA-DMA)核壳乳胶粒子氮元素质量分数达0.29%,折合壳层氨基质量分数达0.78%。     

交联型聚硅氧烷/聚丙烯酸酯复合乳液的制备

在甲基丙烯酰氧丙基三甲氧基硅烷存在下，以交联的聚硅氧烷为种子，丙烯酸酯单体为第二单体，偶氮二异丁腈为引发剂，分别采用间歇法、溶胀法和半连续法制备了聚硅氧烷／聚丙烯酸酯复合乳液。采用透射电子显微镜对乳胶粒子形态进行了表征，发现乳液中形成了以聚丙烯酸酯为核、聚硅氧烷为壳的反相核壳结构乳胶粒子；放置90天后，乳胶粒子的形态未发生翻转；将复合乳液破乳后分析，聚合物凝胶量达到96％以上，说明聚合体系交联很好。     

表层含羟基核壳乳胶粒子PBA-P(MMA-VA)的制备

采用预乳化-半连续种子乳液聚合法制备了聚丙烯酸丁酯(PBA)-聚(甲基丙烯酸甲酯-乙酸乙烯酯)[P(MMA-VAc)]核壳乳胶粒子,然后经醇解得到表层含羟基的PBA-聚(甲基丙烯酸甲酯-乙烯醇)[P(MMAVA)]核壳乳胶粒子。采用傅里叶变换红外光谱仪、差示扫描量热仪及透射电子显微镜等表征了核壳乳胶粒子的结构和形态。结果表明:PBA-P(MMA-VAc)为核壳结构,核壳乳胶粒子的平均粒径为340 nm,其中PBA核的平均粒径为270 nm;功能单体乙酸乙烯酯(VAc)参与了壳层共聚合,并且部分P(MMA-VAc)成功接枝到PBA核上;VAc用量增加导致壳层交联度提高、玻璃化转变温度上升,当VAc用量为壳层单体质量的20%时,壳层中以化学键连接在PBA核上的乙烯醇质量分数达5.44%。     

表面含磺酸基的核-壳型乳胶粒子的制备与表征

为了合成表面含磺酸基的双亲型核-壳聚合物,本文采用两步乳液聚合法,第1步合成PS种子乳液;第2步用氧化还原引发体系在PS种子乳胶粒外包覆1层交联的聚苯乙烯磺酸酯,得到表面含磺酸酯的核-壳型聚苯乙烯(CPS)乳胶粒子。通过调节壳层单体的加入量,可以控制外壳层聚合物的质量分数(相对核层)在10%~30%之间。将外壳层的磺酸酯基水解转化成磺酸基得目标产物。用透射电子显微镜(TEM)、红外光谱(IR)、差热分析(DSC)和热失重分析(TGA)、X射线光电能谱(XPS)等方法对制备的乳胶粒子进行了测试和表征。     

环糊精对聚合物乳胶粒子性能影响的研究

以苯乙烯（St）和甲基丙烯酸丁酯（BMA）为单体,采用核壳乳液聚合的方法,制备了苯丙乳胶粒子。研究了不同含量β-环糊精(β-CD)对聚合体系反应过程及苯丙乳胶粒子性能的影响。动态光散射(DLS)数据显示,制备的乳胶粒子粒径小且分布窄,分布均匀,具有单分散性;接触角表明,乳胶膜的亲水性增强,表面能较改性前有所增加;原子力显微镜(AFM)和透射电子显微镜(TEM)表明,改性后乳胶粒子为核壳结构,粒径分布均匀,大小均一;当β-CD含量为5 %时,制得的苯丙乳液聚合物综合性能最佳。     

羧基磁性高分子微球的性能表征

以改性后得到的Fe3O4-KH-570粒子为核,运用分散聚合法合成羧基磁性高分子微球,采用紫外光谱仪、红外光谱(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等手段进行表征。结果表明,该羧基磁性高分子微球粒子平均粒径为350nm,磁响应性良好,具有明显的核壳结构。     

Morphological prediction and its application to the synthesis of polyacrylate/polysiloxane core/shell latex particles

A theoretical analysis and a morphological prediction of polyacrylate (PA)/polysiloxane (PSi) latex particles with core/shell morphologies were first conducted based on interfacial tensions and relative volumes of the two polymers in the latex system. The results indicated that the normal core/shell morphology particles (PSi/PA), with hydrophobic polysiloxane as the core and with hydrophilic polyacrylate as the shell, can be easily formed. Although the inverted core/shell morphology particles (PA/PSi) with polyacrylate as the core could not be formed in most cases, even if the fraction volume of polysiloxane was larger than 0.872, which is the smallest value of forming a PA/PSi particle, the PSi/PA particles were unavoidably formed simultaneously with PA/PSi particle formation. The synthesis of PA/PSi particles containing equal amounts of polyacrylate and polysiloxane was then carried out using seeded emulsion polymerization. Before the cyclosiloxane cationic polymerization, 3‐methacryloyloxypropyl trimethoxysilane (MATS) was introduced into the polyacrylate seed latex to form an intermediate layer and chemical bonds between the core and the shell polymers. The characterization by transmission electron microscopy (TEM) demonstrated that the perfect PA/PSi core/shell particle is successfully synthesized when both the core and the shell polymers are crosslinked. The experiments showed that both the hardness and water adsorption ratio characteristics of latex films of the PA/PSi particles are in good agreement with those of the polysiloxane film. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2251–2258, 2001     

有机-无机杂化核壳型乳胶粒的制备及其粒径控制

以苯乙烯乳液聚合合成种子,再在种子外生成苯乙烯与甲基丙烯酸-3-三甲氧基硅丙酯（MPS）的共聚物,利用MPS中硅氧烷基的水解-缩合反应,形成交联的壳,得到有机-无机杂化型核壳乳胶粒.然后用溶剂将聚苯乙烯模板溶解,可得到空心微胶囊.通过透射电镜（TEM）和动态光散射粒径仪（DLS）观测乳胶粒及微胶囊的形态.并研究了乳化剂种类、介质pH值、MPS用量和加入方式对粒径、粒子数和体系稳定性的影响.发现非离子型乳化剂、酸性或碱性介质、MPS用量过多均促进乳胶粒子数减少,减弱了乳液稳定性.而采取连续滴加MPS的方法则可提高乳液的稳定性,且粒径可控.     

The effect of the polymerization route on the amount of interphase in structured latex particles and their corresponding films

Three series of hard/soft styrene-acrylic latex based systems with equivalent compositions were prepared either by blending of homopolymer latexes or by preparing structured latex particles having core shell (CS) or inverted core shell (ICS) morphologies. Transmission electron microscopy (TEM) was used to investigate the particle morphologies, which were correlated to the calculated fractional radical penetration for the propagating species during the reactions. The thermo-mechanical properties as well as the morphology of the resulting latex films were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and TEM. The viscoelastic properties of the interphase between the first and second-stage polymers formed in the structured hard/soft latex films, as well as its qualitative amount and also the film morphologies were found to depend on the interplay between thermodynamic and kinetic parameters during the synthesis of the samples.     

Preparation of the stable core–shell latex particles containing organic-siloxane in the shell

In this study, the latex particles with a polyacrylate core and a polydimethylsiloxane shell via 3-(methacryloxypropyl)-trimethoxysilane as the space arm to link the core and shell have been prepared by semi continuous seeded emulsion polymerization. And several key polymerization reaction conditions such as the emulsifier concentration, 3-(methacryloxypropyl)-trimethoxysilane dosages, feeding sequence and the acrylates/siloxanes ratio were detailedly discussed. Then, the optimal condition to prepare stable core/shell particles was selected and a proper preparation process has been established. The as-synthesized particles were characterized by TEM and XPS. The clear core/shell structure of the particles could be observed through analysis TEM. In addition, the results of XPS analyses manifested that siloxanes had been grafted on the surface of the polyacrylate particles and they distributed on the outmost layer of the particles. Finally, the surface hydrophobicity of the film formed by latex particles was investigated by the water absorption ratio measurement. The results indicated the developed latex particle provided with a fair water-repellency property.     

Investigation of fluorinated polyacrylate latex with core–shell structure

Fluorinated polyacrylate latices with core–shell structure were prepared by semi‐continuous emulsion polymerization, using a mixed emulsifier system composed of a reactive emulsifier and a small amount of anionic emulsifier. The conversion and chemical components of the final latices were studied by gravimetric methods and Fourier‐transform infrared (FTIR) spectrometry, respectively. The structure of the latex particles was determined by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and particle size analysis. The latex films exhibited a low surface energy and high water‐contact angles. The surface analysis from X‐ray photoelectron spectroscopy (XPS) revealed that the fluorinated components preferentially self‐organized at the film–air interface. From XPS depth profiling of the film, it was found that a gradient concentration of fluorine existed in the structure of the latex film from the film–air interface to the film–glass interface. Compared with the core–shell structure with a fluorinated core, the core–shell structure with a fluorinated shell was more effective for modifying the properties of the latex films. Copyright © 2005 Society of Chemical Industry     

Preparation and characterization of poly(butadiene-stat-styrene)/poly(styrene-stat-acrylonitrile) structured latex particles

In rubber toughening of thermoplastics, core/shell polymers have been used extensively. This work introduces the synthesis and characterization of polybutadiene based core/shell latex particles with controlled particle size and crosslinking density of the core. A lithium soap recipe was employed to prepare a series of poly(butadiene-stat-styrene) (90/10 by wt) core particles by conventional emulsion polymerization through a batch process. The shell polymer, poly(styrene-stat-acrylonitrile) (72/28 by wt), was polymerized by a semicontinuous process in the presence of the core particles to form a core/shell morphology. The effects of initiator concentration, monomer feeding rate, core/shell ratio, and gel-fraction of the core on the core/shell particle morphology were studied. The degree of grafting of the shell polymer on the core particles was determined as well. The morphology and glass transitions of these particles were characterized by transmission electron microscopy, differential scanning calorimetry, and dynamic mechanical spectroscopy. These latex particles can be used specifically in toughening polycarbonate. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1123–1134, 1997     

Particle size and morphology of poly[styrene‐co‐(butyl acrylate)]/nano‐silica composite latex

Nanocomposite latex with nano‐silica of varying particle sizes was prepared via in situ polymerization and investigated by submicron particle size analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier‐transform infrared spectrometry (FTIR) and Raman spectrometry. It was found that nanocomposite latex exhibited a core–shell structure with nano‐silica particles enwrapped, resulting in an increase in the latex particle size. The smaller the nano‐silica particles, the more were embedded in each latex particle. The increase in the particle size of latex depended not only on the particle size of nano‐silica, but also on the number of nano‐silica particles in each latex particle. Copyright © 2004 Society of Chemical Industry     

Particle morphology and NMR structure of polymethylmethacrylate/polystyrene emulsifier‐free core–shell cationic latices in the presence of DBMEA

In the absence of emulsifier, we prepared stable emulsifier‐free polymethylmethacrylate/polystyrene (PMMA/PSt) copolymer latex by batch method with comonomer N,N‐dimethyl, N‐butyl, N‐methacryloloxylethyl ammonium bromide (DBMEA) by using A1BN as initiator. The size distribution of the latex particles was very narrow and the copolymer particles were spherical and very uniform. Under the same recipe and polymerization conditions, PMMA/PSt and PSt/PMMA composite polymer particle latices were prepared by a semicontinuous emulsifier‐free seeded emulsion polymerization method. The sizes and size distributions of composite latex particles were determined both by quasi‐elastic light scattering and transmission electron microscopy (TEM). The effects of feeding manner and staining agents on the morphologies of the composite particles were studied. The results were as follows: the latex particles were dyed with pH 2.0 phosphotungestic acid solution and with uranyl acetate solution, respectively, revealing that the morphologies of the composite latex particles were obviously core–shell structures. The core–shell polymer structure of PMMA/PSt was also studied by ¹H, ¹³C, 2D NMR, and distortionless enhancement by polarization transfer, or DEPT, spectroscopy. Results showed that PMMA/PSt polymers are composed of PSt homopolymer, PMMA homopolymer, and PMMA‐g‐PSt graft copolymers; results by NMR are consistent with TEM results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1681–1687, 2005     

Synthesis and characterization of core/shell ionomeric latexes. I. Latex and film properties

This research work involved studies on the synthesis and characterization of core/shell ionomeric latexes in order to understand the process of ionic aggregate formation. The core/shell structure of the ionomeric latexes prepared in this study confines the ionic domains to the copolymeric matrix within the shell polymer, and in addition, benefits from the ionomeric properties and core/shell structure simultaneously. Core/shell ionomeric latexes with polystyrene cores and styrene/n-butyl acrylate/methacrylic acid terpolymer shells were synthesized by a semicontinuous seeded emulsion copolymerization process. The distribution of the methacrylic acid in the core/shell latexes was determined using conductometric titration techniques. The results of the conductometric titration analysis indicate that the principal locus of the carboxyl groups in the core/shell latexes is at the particle surface, but specific information about the differences in the distribution of methacrylic acid inside the latex particles could not be obtained. Mechanical characterization of the core/shell ionomeric latex films was carried out to understand the structure-property relationships using Dynamic Mechanical Analysis (DMA) and tensile testing. It was discovered that the core/shell latexes exhibited significantly different properties, owing to the differences in the overall carboxyl content and surface loading. Extensive studies were carried out to study the effect of water plasticization on the mechanical behavior of the core/shell ionomeric latex films; water adsorption causes the solvation of ionic aggregates. A preliminary investigation of the effect of the type of counterion used for the neutralization of carboxyl groups on the properties of core/shell ionomeric latex films was also carried out. © 1995 John Wiley & Sons, Inc.