苯乙烯微乳液种子聚合

通过观测苯乙烯微乳液种子聚合前后体系内聚合物粒子大小及其分布的变化发现,无论是γ射线还是KPS引发,聚合过程中都没有新的聚合物粒子生成。尽管聚合前体系中存在单体溶胀的胶束,但在聚合过程中这些胶束主要充当单体仓库,自己成核聚合的几率很低。由于微乳液种子聚合体系内,单体量相对较低,聚合物粒子数目很大,其聚合动力学明显不同于常规乳液种子聚合。     

有机硅-丙烯酸酯聚合物乳液合成及粒径分析

通过种子乳液半连续法合成了有机硅改性丙烯酸酯聚合物乳液,并对其粒子形态及分布进行分析。结果表明:通过种子乳液半连续聚合工艺可制备出固含量42wt%,乳化剂含量4wt%(基于单体量)、窄分布纳米粒子的有机硅改性丙烯酸酯聚合物乳液。随反应进行,粒径分布变窄,平均粒径逐渐增大。随乳化剂中SDS与OP-10的摩尔比减少,粒径增大。     

有机硅-丙烯酸酯微乳液的合成与表征

采用高温乳化种子单体滴加法制备了有机硅-丙烯酸酯共聚微乳液。对合成条件及微乳液的性能进行了研究。用红外光谱(FT-IR)、透射电镜(TEM)、动态激光粒度仪(PCS)对微乳液的结构和粒子形态进行了表征。结果表明:有机硅氧烷与丙烯酸酯发生了共聚反应,生成的微乳液粒子大致为球形结构,粒子大小比较均一,粒径较小。     

有机硅改性丙烯酸酯乳液的合成

乳液聚合;涂料;有机硅改性丙烯酸酯乳液的合成     

丙烯酸酯纳米乳液的制备与表征

将甲基丙烯酸羟乙酯(HEMA)与甲基丙烯酸(MAA)或丙烯酸(AA)用作甲基丙烯酸甲酯(MMA)／丙烯酸丁酯(BA)乳液聚合体系的反应性助乳化剂，采用一种改进的微乳液聚合方法，合成了高单体／乳化剂比例(大于40：1)的聚丙烯酸酯纳米乳液．讨论了引发剂、乳化剂、助乳化别对乳胶粒大小和胶膜吸水率的影响，并对乳液的流体力学行为，共聚物的拉伸行为及耐水性等进行了研究．     

O／W微乳液催化苯乙烯聚合动力学研究

Ｏ／Ｗ微乳液催化苯乙烯聚合动力学研究１）郝京诚孙海英汪汉卿２）（中国科学院兰州化学物理研究所兰州７３００００）尤进茂（曲阜师范大学化学系曲阜２７３１６５）关键词微乳液催化苯乙烯聚合动力学分类号Ｏ６４３．１３微乳液作为聚合反应介质，催化单体聚合反应研究...     

TEM研究苯乙烯微乳液聚合机理

用透射电镜(TEM)对苯乙烯(St)/十二烷基硫酸钠(SDS)/正戊醇/水的O/W微乳液体系在反应前、聚合过程中和反应结束后等不同时间里进行观察,并测定苯乙烯微乳液聚合前后粒径的大小,根据粒径大小的变化研究苯乙烯微乳液聚合成核机理,发现其成核位置主要是在胶束和单体微珠滴里。此外,还发现SDS/St的质量比越大,相对分子质量越低。     

硅丙乳液的合成工艺研究

采用半连续种子乳液聚合工艺,以乙烯基三乙氧基硅烷(VTS)为改性剂、十二烷基硫酸钠(SDS)和烷基酚聚氧乙烯醚(OP-1O)为复合乳化体系,在引发剂过硫酸铵(APS)的作用下合成稳定的硅丙乳液.利用红外光谱(FTIR)和扫描电镜(SEM)对涂膜进行了表征.结果表明:单体转化率随乳化剂用量、引发剂用量、有机硅用量、聚合温...     

光散射法研究丙烯酸十八酯和苯乙烯微乳液 共聚机理

在十六烷基溴化吡啶/叔丁醇/15%丙烯酸十八酯和苯乙烯/水体系的O/W微乳液中,使用动态光散射法,研究其中两种单体共聚反应的成核机理。结果表明,聚合过程中乳胶粒成核位置主要在增溶胶囊的单体微珠中,乳胶粒主要依靠单体微珠不断提供单体而长大。     

反应性乳化剂对有机硅-丙烯酸酯乳液共聚合的影响

有机硅改性丙烯酸酯;乳液聚合;反应性乳化剂对有机硅-丙烯酸酯乳液共聚合的影响     

Effect of dose rate on emulsion and microemulsion polymerization of styrene

Emulsion and microemulsion polymerization of styrene were initiated with a gamma ray to study the effect of dose rate on polymerization. In both systems, there is an apparent plateau of polymerization rate in the curve of reaction rate vs. conversion. It was shown that emulsion polymerization conformed to the Smith–Ewart theory very well. Changing the dose rate in interval 2 had no great influence on polymerization rate, but it changed the average lifetime of radicals in polymer particles and affected the molecular weight of polymer produced. For microemulsion polymerization it was assumed that in the plateau it is the number of growing polymer particles being kept constant, not the number of polymer particles. When the dose rate was changed while the polymerization came into the constant period, the polymerization rate and the molecular weight of the polymer varied with the dose rate. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 257–262, 1998     

K2S2O8/Na2SO3引发St/BA微乳液共聚合的研究

以十二烷基硫酸钠／十二烷基苯磺酸钠(SDS／SDBS)为乳化剂，过硫酸钾／亚硫酸钠(K2S2O3／Ni2SO3)为引发剂进行苯乙烯／丙烯酸丁酯(SL／BA)微孔液共聚合反应。研究了引发剂浓度[I]OR、单体总浓度[M]、乳化剂含量[E]和聚合温度T对微孔液共聚合最大反应速率Rmax和共聚物粘均分子量^-Mη的影响，测定了共聚单体的竞聚率，结果得到：Rmax∝[I]^0.98OR[M]^0.81[E]^-0．34e^-4712／T，^-Mη∝[I]^-0.27OR[M]^0.48[E]^-0.68e^2304/T；rSt=0.598，rBA=0.0206。     

Seeded microemulsion polymerization of butyl acrylate

The seeded microemulsion polymerization of butyl acrylate was studied with γ-rays. The hydrodynamic diameter and its distribution of polymer particles in the seeded microemulsion before and after polymerization were determined with photon correlation spectroscopy (PCS). Though there were micelles in the microemulsion, it was found that new particle formation could be ignored during polymerization. The polymerization kinetics of the seeded microemulsion was investigated. The polymerization rate increases with the dose rate and added monomer content and decreases with the seed fraction. It was completely different from that for seeded emulsion polymerization. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2631–2635, 1998     

乙烯基硅烷-丙烯酸酯乳液共聚动力学研究

以乙烯基三乙氧基硅烷(VTES)、丙烯酸酯为单体,乙氧基醇磺基琥珀酸二钠(A—102)为乳化剂,合成了有机硅改性丙烯酸酯共聚乳液。研究了乳化剂、引发剂、VTES、反应温度以及功能性单体甲基丙烯酸羟乙酯(HEMA)对乳液共聚反应速率的影响。结果表明:聚合速率随乳化剂浓度、引发剂浓度、HEMA浓度的增大及反应温度的升高而增大,但随VTES浓度增大而逐渐减小。由实验得出恒速阶段聚合反应速率R_p与乳化剂浓度C_E、引发剂浓度C_1及有机硅单体浓度C_(VTES)的关系为R_p∝C_E~(0.35)C_I~(0.48)C_(VTES)~(-0.64),表观活化能E_a为81.1kJ·mol~(-1)。     

Kinetics of the potassium persulfate-initiated inverse emulsion polymerization of sodium acrylate solutions

The kinetics of the K₂S₂O₈-initiated inverse emulsion polymerization of aqueous sodium acrylate solutions in kerosene with Span 80 as the emulsifier has been studied. The conversion-time curves are S-shaped. The following expressions have been obtained for the maximum rate of polymerization and the molecular weight of the polymers under the experimental conditions investigated: R_max ∞ [K₂S₂O₈]^0.78[sodium acrylate]^1.5[Span 80]^0.1, (OVERLINE)M(/OVERLINE)_u ∞ [K₂S₂O₈]^−0.37[sodium acrylate]^2.9[Span 80]^−0.2. The activation energy for the maximum rate of polymerization is 94.8 kJ mol^−1. The results suggest a monomer–droplet–nucleation mechanism for the system studied. © 1996 John Wiley & Sons, Inc.     

室温自交联型聚丙烯酸酯纳米乳液的研究

本文分别用反应性乳化剂和常规乳化剂合成了室温自交联丙烯酸纳米乳液,并对其乳液的流变性能进行了研究,发现:反应性乳化剂所得乳液的表观粘度ηa、稠度系数K、零剪切粘度η0均比常规乳化剂所得乳液的增大。并用XPS对乳胶膜进行分析表明,反应性乳化剂在乳液的干燥成膜过程中不易向胶层表面迁移富集。与常规乳化剂体系的乳液相比,反应性乳化剂体系的乳液挥发速率快,吸水率低。并对两种乳液进行了粒径大小及分布的表征。     

防污涂料用丙烯酸树脂的合成研究

以偶氮二异丁腈为引发剂,利用溶液聚合的方法,对丙烯酸、丙烯酸酯和甲基丙烯酸酯进行三元共聚,合成了带有羧酸基团的丙烯酸树脂共聚物,红外光谱表征结果与预期产物所含基团吻合。对反应过程中各个影响因素进行了讨论,并由正交实验得出了最优化的合成条件:引发剂用量为2.5%,单体质量分数40%(wt.),加热温度80℃,及单体滴加时间为2.5h。该合成树脂具有稳定的分子量及粘度,可与金属盐的反应用来制备防污涂料的基料。     

Polymerization of styrene with ionic comonomer,nonionic comonomer,or both

Nanosized polystyrene latexes with high polymer contents were obtained from an emulsifier-free process by the polymerization of styrene with ionic comonomer, nonionic comonomer, or both. After seeding particles were generated in an initial emulsion system consisting of styrene, water, an ionic comonomer [sodium styrenesulfonate (NaSS)] or nonionic comonomer [2-hydroxyethyl methacrylate (HEMA)], and potassium persulfate, most of the styrene monomer or a mixture of styrene and HEMA was added dropwise to the polymerizing emulsion over 6 h. Stable latexes with high polystyrene contents (≤25%) were obtained. The latex particle weight-average diameters were largely reduced (41 nm) by the continuous addition of monomer(s) compared with those (117 nm) obtained by the one-pot polymerization method. Latex particles varied from about 30 to 250 nm in diameters, whereas their molar masses were within 10⁴ to 10⁵ g/mol. The effect of the comonomer concentration on the number of polystyrene particles per milliliter of latex and the weight-average molar masses of the copolymers during the polymerization are discussed. The surface compositions of the latex particles were analyzed by X-ray photoelectron spectroscopy, which indicated that the surface of the latex particles was significantly enriched in NaSS, HEMA, or both. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1634–1645, 2001