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。     

甲基丙烯酸-3-三甲氧基硅丙酯/苯乙烯共聚乳胶粒微结构

我们曾制备了核-壳结构的杂化乳胶粒, 并用溶剂将核去除得到杂化空心微胶囊. 但由于此乳液聚合过程十分复杂, 在不同条件下反应得到乳胶粒的微结构有较大不同, 目前尚未见到各反应条件下所得产物微结构的表征和形成机理的研究报道. 本文将系统分析在不同反应条下, MPS和St种子乳液聚合过程中, 得到的乳胶粒壳层杂化聚合物的微结构, 并研究了其形成原因.     

种子乳液聚合物胶粒形态及胶膜结构研究

以醋酸乙烯酯和丙烯酸丁酯为单体，用乳液聚合方法，以极性小的ＰＢＡ为种子进行了ＶＡ种子聚合，用透射电镜染色及皂液滴定方法对胶粒形态进行了表征，结果，上述聚合反应能形成ＰＢＡ／ＰＶＡ核壳结构的胶粒，而以ＰＶＡ为种子对ＰＢＡ进行聚合，则不能形成ＰＶＡ／ＰＢＡ核壳结构的胶粒，其胶粒亦具有类似ＰＢＡ／ＰＶＡ核壳结构或半包囊结构，将胶乳制成胶膜，其耐水性能测试表明成膜后胶粒基本保持了其分散阶段的形态。     

醋酸乙烯酯-丙烯酸丁酯乳液共聚乳胶粒形态演化过程的模拟

将簇迁移动力学拓展应用到共聚形态的研究中，对醋酸乙烯酯 丙烯酸丁酯从间歇到不同加料速率下的半连续乳液共聚实验的乳胶粒形态演化过程进行了模拟，模拟从共聚 均聚转折点开始．结果说明：半连续加料时，随着加料速率加快，相分离程度增加，间歇反应时形成了核壳结构．乳胶粒形态模拟结果与文献对此共聚乳胶粒形态的实验表征结果类似．     

一种具有核-壳结构的聚合物纳米胶粒的制备及其药物运载性能

以丙烯酸异丁酯(IBA)、甲基丙烯酸二甲氨乙酯(DMAEMA)、丙烯酸羟乙酯(HEA)作为聚合单体,利用种子微乳液聚合制备了一种具有核-壳结构的聚合物纳米胶粒P(DMAEMA-co-IBA)/P(IBA-co-HEA);采用红外光谱仪、动态激光光散射仪、透射电镜分析了所得胶粒的结构和形貌;将叶酸成功嵌入聚合物胶粒,得到直径约293nm的球形载药胶粒,利用药物体外释放测定了药物运载性能.结果表明,所制备的共聚物纳米胶粒呈球形,直径约275nm,粒径分布较窄,并具有核-壳结构;其对药物具有缓释性和pH响应性.     

核壳型PVAc/PBA乳胶粒热力学平衡状态

乙酸乙烯酯;形态;核壳型PVAc/PBA乳胶粒热力学平衡状态;核壳结构;丙烯酸丁酯;乳液聚合;     

核壳型PVAc/PBA乳胶粒热力学平衡状态

乙酸乙烯酯;形态;核壳型PVAc/PBA乳胶粒热力学平衡状态;核壳结构;丙烯酸丁酯;乳液聚合;     

种子乳液聚合中复合乳胶粒结构形态的热力学分析

为了得到一种能够预测和控制乳胶粒结构形成的定量方法，本研究选用含有两 种聚合物乳胶粒(P_a和P_b)和水的体系作为模型体系来模拟种子乳液聚合体系，在 不考虑动力学因素的条件下，对乳胶粒可能出现的三种极限形态进行了热力学分析 。结果表明，最终乳胶粒稳定的结构形态不仅取决于体系中的P_a，P_b和水三者之 间的界面张力γ_(aw)，γ_(bw)和γ_(ab)，而且还取决于两聚合物的体积分数 V_a和V_b。形成P_a/P_b型正核壳结构乳胶粒的热力学必要条件是(γ_(aw)-γ_ (bw))/γ_(ab) > V_a~(2/3)-V_b~(2/3)和(γ_(aw)-γ_(ab))/γ_(bw) > (1- V_b~(2/3))/V_a~(2/3)；形成P_a/P_b型反核壳结构乳胶粒的热力学必要条件是(γ _(aw)-γ_(bw))/γ_(ab) < V_a~(2/3)-V_b~(2/3)和(γ_(bw)-γ_(ab))/γ_(aw) > (1-V_a~(2/3))/V_b~(2/3)。对以聚丙烯酸酯为种子有机硅氧烷的乳液聚合体系 的初步研究结果表明，所得乳胶粒的结构形态与利用上述热力学关系式预测的结果 基本一致。     

核-壳粒子增韧聚合物的研究进展

核-壳粒子增韧结合了弹性体增韧和刚性粒子增强的优点，将其用于聚合物共混体系中有可能得到比基体树脂更高韧性更好刚性的复合材料。本文综述了相关核-壳粒子的分类、形态、形成机制，以及它们对聚合物基体的增韧机理，并详细阐述了反应性和非反应性聚合物共混体系中原位形成的核-壳粒子形态演化规律及其对共混物力学性能的影响。     

荧光探针法研究核壳结构有机硅-丙烯酸酯乳液的聚合行为

以芘为荧光探针,探讨了有机硅-丙烯酸酯核壳乳液聚合过程中,芘的第一振动峰(373 nm处)与第三振动峰(384 nm处)荧光强度的比值I1/I3与乳化剂、有机硅单体(D4)和引发剂(KPS)用量之间的关系,并结合聚合过程中探针芘的I1/I3峰值与单体转化率及乳胶粒形态演变之间的关系,研究了核壳结构有机硅-丙烯酸酯乳液的聚合行为.研究结果表明,探针芘的I1/I3峰值随乳化剂用量,D4用量,KPS用量不同发生相应的变化,随单体转化率的增加而增大.当乳化剂用量、D4用量、KPS与总单体的质量比依次为2 g、8 g、0.7%时,得到的乳液具有优良的综合性能.聚合反应过程中,当种子乳胶粒转变为核壳乳胶粒时,芘的I1/I3峰值仍呈现出明显的转变,说明有机硅-丙烯酸酯核壳乳液具有互穿聚合物网络结构.因此,荧光探针可用于研究有机硅-丙烯酸酯核壳乳液聚合反应进程.     

Effect of the Shell Crosslinking Level andCore/Shell Ratio on the Morphology of LatexParticles in the Preparation of Hollow Latexes简

Three-layer core/shell latex particles with various shell crosslinking level and shell thickness were prepared by multistep emulsion polymerization, and the hollow latex particles with different morphologies were then obtained after alkali post-treatment. Influences of divinyl benzene(DVB) content and the core/shell mass ratio on emulsion polymerization and particle morphology were investigated. Results showed that with the increase of DVB content, the percentage of total amount of ―COOH on the particle surface and free in aqueous phase(PSFa) decreased, and the morphology of the post-treated particles underwent evolution from cracked, intact hollow to deficient swelling structure. Decreasing the core/shell mass ratio could not only make more carboxyl groups encapsulated by the shell, but also increase the shell resistance to the swelling of the core. The uniform hollow latex particles with intact morphology were obtained when the DVB content was 3.54 wt% and the core/shell mass ratio was 1/6.     

反应性复合乳液的合成、表征及其交联反应

利用种子半连续乳液聚合方法合成了核层或壳层带有环氧基以及壳层带有羧基的3种不同核/壳结构的乳胶粒子,通过物理共混带环氧基和羧基的乳胶粒子,得到了两种反应性复合乳液.利用透射电镜和激光动态光散射对乳胶粒子进行了表征,其粒径分布较窄,粒径分布的多分散系数为0.062,平均粒径约76 nm,乳胶粒子具有明显的核/壳结构.通过胶膜的凝胶率和膨胀率的测定和红外光谱分析对反应性复合乳液中乳胶粒子的扩散及交联反应进行了研究,并探讨了不同核壳结构复合乳液对涂膜机械性能的影响.研究表明,当反应性复合乳液中的环氧基和羧基分别分布在乳胶粒子的核层和壳层时,有利于聚合物分子链的充分扩散和化学交联反应的进行,从而提高涂膜的物理化学性能,当甲基丙烯酸缩水甘油酯(GMA)含量为10 wt%时,涂膜的拉伸强度达20.3 MPa.     

Preparation,morphology, and thermoresponsive properties of poly(N‐isopropylacrylamide)‐based copolymer microgels

In this research, thermoresponsive copolymer latex particles with an average diameter of about 200–500 nm were prepared via surfactant‐free emulsion polymerization. The thermoresponsive properties of these particles were designed by the addition of hydrophilic monomers [acrylic acid (AA) and sodium acrylate (SA)] to copolymerize with N‐isopropylacrylamide (NIPAAm). The effects of the comonomers and composition on the synthesis mechanism, kinetics, particle size, morphology, and thermoresponsive properties of the copolymer latex were also studied to determine the relationships between the synthesis conditions, the particle morphology, and the thermoresponsive properties. The results showed that the addition of hydrophilic AA or SA affected the mechanism and kinetics of polymerization. The lower critical solution temperature (LCST) of the latex copolymerized with AA rose to a higher temperature. However, because the strong hydrophilic and ionic properties of SA caused a core–shell structure, where NIPAAm was in the inner core and SA was in the outer shell, the LCST of the latex copolymerized with SA was still the same as that of pure poly(N‐isopropylacrylamide) latex. It was concluded that these submicrometer copolymer latex particles with different thermoresponsive properties could be applied in many fields. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 356–370, 2006     

Morphology and grafting reactions in core/shell latexes

The particle morphology and percent grafting were investigated as a function of the crosslink density of the seed latex in two systems of core/shell latexes of polybutadiene/polymethyl methacrylate (PB/PMMA) and styrene–butadiene rubber/polymethyl methacrylate (SBR/PMMA) prepared by seeded emulsion polymerization at 50°C. The thin layer chromatography/flame ionization detection (TLC/FID) technique was used to characterize the grafting efficiency of the core/shell latexes. The percent grafting of the shell polymer was found to decrease with increasing the crosslink density of the core material. The particle morphology and precent grafting were also investigated as a function of composition and structure of the core material in four core/shell latex systems: polybutadiene/styrene–acrylonitrile copolymer (PB/SAN), (styrene-butadiene) random copolymer/styrene acrylonitrile copolymer (S:B/SAN), polystyrene : polybutadiene/styrene-acrylonitrile copolymer (PS:PB/SAN) and Kraton/styrene-acrylonitrile copolymer (Kraton/SAN), which were prepared by direct emulsification for the seed followed by emulsion polymerization at 70°C for the shell polymer. Grafting and crosslinking of the core material were found to be competitive reactions depending on the microstructure of the seed latex.     

Particle morphology of self-hydrolyzed acrylate polymer colloids: A 13C NMR and DSC study

Methyl acrylate polymer colloids can be hydrolyzed self-catalytically by bound strong acid surface groups derived from the polymerization initiator. The kinetics of hydrolysis were earlier shown to be apparently pseudo-zeroth-order for any given latex, and first order with respect to surface strong acid concentration. A surface reaction zone model was proposed to explain the kinetics. This model leads to the prediction that the polymer particles will possess a core-shell morphology after some hydrolysis has occurred. This study employs ¹³C NMR spectroscopy to investigate the particle morphology in the wet latex, a new application for this method. The temperature dependence of the ¹³C NMR integrated intensities at various levels of hydrolysis provides strong evidence that the particles do possess core-shell morphology, and that the shell is composed of PAA/PMA copolymer. This shell is swollen and plasticized by water, resulting in greatly enhanced segmental mobility of the polymer chains as evidenced by marked narrowing of the NMR lines. Thermal measurements alone cannot distinguish particle morphology because PMA appears to be somewhat compatible with its partially hydrolyzed analog at the temperatures of measurement.     

Effects of shell composition,dosage and alkali type on the morphology of polymer hollow microspheres

Polymer hollow microspheres were prepared by performing alkali treatment on the multilayer core/shell polymer latex particles containing carboxyl groups. Effects of the shell composition and dosage as well as alkali type on the morphology of the microspheres were investigated. Results showed that in comparison with acrylonitrile(AN) and methacrylic acid(MAA), using butyl acrylate(BA) as the shell co-monomer decreased the glass transition temperature(T_g) of shell effectively and was beneficial to the formation of uniform and big hollow structure. Along with the increase of the shell dosage, the alkali-treated microspheres sequentially presented porous and hollow morphology, and the size of microspheres increased, while the hollow diameter increased first and then decreased, and the maximum hollow ratio reached 39.5%. Furthermore, the multilayer core/shell microspheres had better tolerance to NH_3·H_2O than to NaOH. When the molar ratio of alkali to methacrylic acid(MR_(alkali/acid)) for Na OH ranged from 1.15 to 1.30 or MRalkali/acid for NH_3·H_2O ranged from 1.30 to 2.00, the regular polymer hollow microspheres could be obtained.     

聚硅氧烷/丙烯酸酯核/壳复合胶乳的粒径分布与成核机理

通过种子乳液法合成出具有高有机硅含量核 壳结构的聚硅氧烷 丙烯酸酯复合粒子 .研究了聚合方法、乳化剂浓度、引发剂浓度、单体滴加速度等工艺条件对复合乳液粒径尺寸、分布与形态的影响 ,并对复合乳液的成核机理进行了探讨 .研究表明 ,乳化剂浓度对乳液粒子的粒径分布和形态、结构有显著影响 ,引发剂浓度增加将使粒子粒径减小 ;相对一次投料法 ,种子乳液法生成的粒子分布窄 ,具有明显核壳结构 ,通过壳层单体滴加速度可以控制粒子的粒径尺寸和分布 ;而壳层丙烯酸酯聚合物主要是在聚硅氧烷种子表面的“过渡层”聚合、富集而成 .     

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.     

Morphology control of magnetic latex particles prepared from oil in water ferrofluid emulsion

The use of magnetic latex particles as solid support in biomedical applications is favourable when homogeneous and well-defined core–shell polymer particles are used. Accordingly, this paper concerns with the synthesis of magnetic poly(styrene–divinylbenzene) latex particles using emulsion polymerization of styrene (St) and divinylbenzene (DVB) monomers in the presence of preformed oil in water organic ferrofluid emulsion droplets as seed. The key parameters which affect on formation and morphology of the prepared magnetic latexes were investigated, including type of magnetic emulsion, St/DVB monomers ratio, DVB amount, type of initiator and surfactant nature. In this study, two different magnetic emulsions were used, low and high octane content magnetic emulsions. The magnetic emulsions were stabilized using different types of surfactants including AP, Triton X 405 and SDS. In addition, four different initiators, including AIBN, V50, ACPA and KPS were examined. The morphology of the prepared magnetic latexes was investigated using transmission electron microscopy. In addition, particle size and size distribution, magnetic content and magnetic properties of the prepared magnetic latexes were also examined, using various techniques, e.g. dynamic light scattering, thermal gravimetric analysis and vibrating sample magnetometer, respectively. The results showed that the morphology type (Janus like, moon like and/or core–shell) of the prepared magnetic latex particles could be controlled depending mainly on the used formulation. In fact, the use of styrene monomer leads to anisotropic morphology. Whereas, the progressive use of DVB in presence of KPS intiator leads to a well-defined magnetic core and polymer shell structure.

种子乳液聚合的研究进展

种子乳液聚合法因具有乳液稳定性更好、粒径分布窄、易控制等优点,在乳胶粒子设计及制备各种功能性胶乳方面具有重要作用,是制备高固含量乳液及具有核壳结构乳液的最常见最简便的方法.本文综述了近年来种子乳液的聚合工艺、聚合机理, 包括接枝机理、互穿聚合物网络机理、聚合物沉积机理、种子表面聚合机理和离子键合机理等,以及种子乳液聚合在乳胶粒子设计方面的应用研究进展,并讨论了影响种子乳液聚合的各种因素.