甲基丙烯酸甲酯乳液聚合中自由解吸及解吸速率常数的分析与计算

在甲基丙烯酸甲酯（MMA）乳液聚合动力学研究的基础上，建立了计算自由基解吸速率常数k0的多元方程式，研究了在MMA乳液聚合过程中K0的变化规律，分析了各种因素对自由基解吸的影响。计算结果表明，K0不仅与单体转化率有关，而且与引发剂浓度、乳化剂浓度、反应温度及相比有关。     

多乙烯基硅油改性丙烯酸酯乳液的合成及性能

以自制阳离子型乳化剂H、多乙烯基硅油和丙烯酸类单体为主要原料,采用一步法和半连续种子乳液聚合法合成有机硅改性丙烯酸酯乳液。研究了不同聚合方法、不同有机硅含量对硅丙乳液乳胶膜的吸水率、疏水性能的影响,通过纳米粒度-Zeta电位分析仪、接触角仪、红外光谱、透射电镜对乳液及聚合物结构进行了表征。结果表明有机硅单体参与了聚合,乳液稳定性好、平均粒径小。采用半连续种子乳液聚合法合成乳液,有机硅最大添加量为40%(占壳层单体总量),乳胶膜的吸水率只有3.2%,对水的接触角达到105.2o。     

镶嵌型乳胶粒子的合成

以苯乙烯、甲基丙烯酸甲酯、丙烯腈等单体或它们的混合物为硬单体,天然胶乳为弹性组分,经多步种子乳液聚合法制得了在天然胶乳的粒子上镶嵌硬聚合物相的互穿网络型乳胶粒子.考察了十二烷基硫酸钠、十二烷基苯磺酸钠、壬基酚聚氧乙烯醚、油酸等乳化体系,过硫酸钾、过氧化苯甲酰热引发体系及异丙苯过氧化氢-四乙烯五胺、叔丁基过氧化氢-四乙烯五胺等氧化还原引发体系对聚合反应的影响.研究了交联剂用量对互穿结合率、溶胶含量的影响及溶胀时间、硬单体组成、乳化剂种类对乳胶粒子形态的影响,确定了适宜的聚合配方和工艺条件.透射电镜观察乳粒形态结果表明,单一使用极性或非极性单体,仅得到核-壳结构乳液,而采用不同极性单体复合、溶胀、互穿,得到的是镶嵌硬聚合物型乳粒结构.     

乳化剂对阳离子乳液聚合及乳胶粒性能的影响

以苯乙烯、丙烯酸丁酯为非离子单体,甲基丙烯酰氧乙基三甲基氯化铵（DMC）为阳离子单体,偶氮二异丁基脒盐酸盐（AIBA）为引发剂,十六烷基三甲基氯化铵（CTAC）和乙撑基双（十六烷基二甲基氯化铵）（G16—2—16）为乳化剂,采用半连续种子乳液聚合法进行阳离子乳液聚合。探讨了乳化剂的分子结构和用量对反应速率、单体转化率以及乳胶粒粒径、Zeta电位等的影响。结果表明：乳化剂的用量越大,反应速率越大,单体转化率越高,而乳胶粒粒径越小;使用G16—2—16作乳化剂时,单体转化率较高,乳胶粒粒径较大,Zeta电位较高。     

羟基硅油改性丙烯酸树脂的合成及其性能

羟基硅油改性丙烯酸树脂的合成及其性能;种子乳液聚合;羟基硅油;丙烯酸酯;玻璃化转变温度     

复合乳液乳胶粒样品的制备

报道了利用火棉胶支持膜制取复合乳液乳胶粒样品的技术,不同于传统制作方法,其所其制备的样品具有分散度好,样品边界清晰等优点.     

“水包水”型阳离子聚丙烯酰胺乳液的合成

The emulsion of cationic polyacrylamide was prepared by a soap-free polymerization,using water as media,the oligomer that prepared by myself as emulsifier and stabilizer,(NH_4)_2S_2O_8 as initiator.The effect of the amount of isopropanol,oligomer and the ratio of DMC/AM on the molecular weight of cationic polyacrylamide were all studied.The best amount of isopropanol,oligomer are 25%,20% of the total monomer and the ratio of DMC/AM is 3/7.     

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...     

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     

水包油型微乳液相色谱分离激素类药物的影响因素

采用水包油型微乳液相色谱(MELC)分离了6种激素类药物(醋酸可的松、泼尼松龙、己烯雌酚、炔雌醇、醋酸氟轻松及黄体酮)。考察了微乳流动相的组成成分(包括表面活性剂的浓度、油相种类、有机添加剂种类)及固定相孔径等对分离的影响。实验得到的最佳分离条件: 色谱柱为Venusil ASB C18 (T)(粒径5 μm,孔径30 nm,250 mm×4.6 mm),微乳流动相为30 g/L十二烷基硫酸钠(SDS)-0.8%正辛烷-6.6%正丁醇,流速为0.8 mL/min,检测波长为254 nm,柱温为35 ℃。该方法可用于甾体药物及其制剂的分离鉴别以及快速测定。     

Microwave Effects Due to Anionic or Cationic Initiators in Emulsion Polymerization Reactions

Summary: Emulsion polymerization reactions were performed under microwave irradiation and conventional heating using anionic or cationic initiators and surfactants. Microwave irradiation promoted higher reaction rates for both initiators and surfactants, in comparison with the conventional heating. The effect of high power microwave irradiation was studied using a method of cycles of heating and cooling, where rapid polymerization reactions were obtained. In the reactions with anionic initiator and surfactant, a decrease in the particle diameters was observed with microwave heating, and even smaller particles were obtained using high power microwave irradiation. Moreover, the decrease in the particle size was acompanied by an increase in the polymer molecular weight. On the other hand, these effects were not observed for reactions with cationic initiator and surfactant.     

无皂乳液聚合法合成阴离子PS微球及粒径控制

以苯乙烯(St)和丙烯酸(AA)为单体,过硫酸钾(KPS)为引发剂,采用无皂乳液聚合法合成了单分散阴离子聚苯乙烯(PS)微球,并对微球结构和影响单分散性的因素进行了研究。结果表明,AA单体也已共聚到聚合物链上,AA的加入使PS微球粒径减小,并赋予PS微球表面负电性;聚合反应的活化能为42.95kJ/mol,升高聚合温度提高了反应速率;随着KPS用量的增加,PS微球粒径减小,在用量为0.6%时呈现最好单分散性;随着反应介质中丙酮含量增加,聚合物在介质中溶解度增加,使PS微球粒径有所减小,但微球粒径分布有所变宽。     

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. II. Polymerization mechanism

The mechanism of growth of latex particles in the emulsion polymerization of vinyl acetate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40; Henkel) was investigated. Both the aqueous phase and the particle/water interface were found to be loci for the copolymerization of TREM LF-40 with vinyl acetate. Competitive growth experiments using TREM LF-40 and its nonpolymerizable derivative were conducted to separate the effects of aqueous phase and particle surface. Particle size analysis of the seeded and unseeded polymerizations coupled with kinetic results suggested that the reactions at the particle/water interface are more important and that the particle size of the latexes is a key parameter controlling the polymerization rate through copolymerization and chain transfer to the polymerizable surfactant at the particle surface. A decrease in particle size lead to an increase in the amount of TREM LF-40 polymerized at the particle surface and to a decrease in polymerization rate. © 1992 John Wiley & Sons, Inc.     

Nucleation in Emulsion Polymerization: Another Step towards Non-Micellar Nucleation Theory

Summary : Comprehensive experimental results of the nucleation stage of styrene emulsion polymerization in the absence as well as in the presence of emulsifier at different concentrations are presented. In addition, the influence of initiator type and presence of seed particles are studied. The nucleation mechanism is verified by means of on-line monitoring of the optical transmission and the conductivity of the aqueous phase. Results prove that micelles do not alter the nucleation mechanism which comprises the initiation of water soluble oligomers in the aqueous phase followed by their aggregation into colloidally stable latex particles. Surfactants assist with nucleation as they lower the activation free energy of particle formation. Contrary, in the presence of seed particles above a critical volume fraction the formation of new particles can be suppressed.     

非离子型可聚合聚氨酯/苯乙烯的超浓乳液聚合

研究了以非离子型可聚合聚氨酯(PUAG)和苯乙烯(St)为混合单体的超浓乳液聚合, 并且考察了n(NCO)/n(OH)摩尔比、复合乳化剂体系质量浓度[E]、不同乳化剂的种类、引发剂质量浓度[I]、单体体积分数(或分散相体积分数, 也称内相比Φ)、聚合温度等因素对聚合稳定性、动力学的影响. 同时结合光相关光谱(PCS)测定了聚合物乳胶粒子大小和粒径分布, 用透射电子显微镜(TEM)观察了粒子形态, 结果表明: 当n(NCO)/n(OH)＝2∶1, T＝328 K, Φ＝80.39%, [I]＝0.8% g/g (PUAG-St), [E]＝0.22 g/mL H₂O, m(MS-1)/m(CA)＝2∶1, PVA＝0.01 g/mL H₂O时, 超浓乳液不仅有较好的聚合稳定性和较快的聚合速率, 而且粒径小分布均匀. 同时, 在此条件下的表观动力学表达式和表观活化能分别确定为R_p＝k[I]^0.50[E]^0.73[M]^0.54和 E_a＝29.7 kJ/mol. 热失重分析(TGA)进一步表明: 调节PUAG的含量可以达到对聚苯乙烯的改性, 提高聚苯乙烯的热稳定性.     

硅氧烷乳液聚合过程中大颗粒形成机理的研究：Ⅱ.聚硅氧烷乳液的耐酸碱…

研究了阴离子型与阳离子型聚硅氧烷乳液的耐酸碱稳定性，发现阴离子型乳液对酸碱都相当稳定，在乳液制备过程中，酸性催化剂不会引起乳液颗粒的凝聚；而阳离子型乳液的耐酸三稳定性性差，尤其是引起乳液颗粒慢速凝聚的碱浓度下限值很低，碱是制备阳离子型乳液的化剂，碱引起乳液颗粒的慢速凝聚是阳离子型乳液中大颗粒形成的主要原因，在乳液聚合过程中所发生的相当部分的乳化剂从水相向有机硅相的转移也是影响阳离子型乳液稳定性的一     

氯丁胶乳乳液接枝甲基丙烯酸甲酯的反应动力学

采用乳液聚合法将甲基丙烯酸甲酯(MMA)接枝到氯丁胶乳上,红外光谱和核磁共振氢谱证实了接枝产物的生成。 研究了反应温度、乳化剂浓度、引发剂浓度和单体浓度对表观聚合速率的影响。 结果表明,当反应温度为50 ℃,引发剂叔丁基过氧化氢 四乙烯五胺（t-BHP/TEPA）用量为氯丁胶乳干重的0.5%,单体/聚合物质量比m(M)∶m(P)=3∶5,乳化剂十二烷基连苯醚二磺酸钠（DSB）用量为单体总质量1%时,单体转化率和接枝效率分别为99.1%和54.9%。 聚合反应动力学关系式为：Rp=Kc(E)0.15c(I)0.30c(MMA)1.41,式中,K为常数,在40~55 ℃范围内,聚合反应的表观活化能Ea＝60.2 kJ/mol。 接枝聚合基本符合自由基反应机理。     

Trialkylsilyl-Protected Functional Initiators for Stereospecific Anionic Polymerization of Methacrylates

Anionic polymerizations of methyl methacrylate with trialkylsilyl-protected lithium benzylamides were conducted in the presence of aluminum compounds such as n-Bu₃Al. When the Me₃Si-protected amide was used, the carbonyl attack took place to some extent to form a methacrylamide derivative with slightly lower initiator efficiency (∼0.9). In the case of i-Pr₃Si-protected amide, the carbonyl addition was completely suppressed. The obtained polymers had narrow molecular weight distribution and carried benzylamino end-group, as revealed by NMR analysis, which is readily accessible for further chemical transformations such as acylation with acryloyl chloride and debenzylation with H₂/Pd-C. Difuntional initiators with protected groups were also examined.     

丁苯胶乳的合成研究

以丁二烯和苯乙烯为单体、十二烷基硫醇为乳化剂,通过一步法合成了大粒径丁苯胶乳（SBR）.结果表明：乳化剂浓度、电解质浓度、固含量及单体加入方式是控制丁苯胶乳粒径大小的关键因素.通过适时补加乳化剂,选取适宜的电解质浓度、固含量及采用种子半连续加料方式有利于控制SBR粒径大小及分布.