【作者】 赖贵贞；

【导师】 李晓；

【作者基本信息】 福州大学 ， 化学工程， 2006， 硕士

【摘要】 随着社会的发展和人类环保意识的增强,超微胶乳发挥着越来越重要的作用,而且分子量及结构可控、分子量分布窄的超微胶乳可进一步拓宽应用领域。本文采用乳液聚合氨化微化法和微乳液聚合法制备了固含量较高而乳化剂含量低的丙烯酸酯超微胶乳和苯丙超微胶乳,同时将原子转移自由基聚合（ATRP）引发催化配位体系引入微乳液聚合,对在苯乙烯微乳液中实施ATRP可控聚合进行了探索,并研究了ATRP微乳液体系的聚合动力学。先采用单体两段滴加法乳液聚合得到常规胶乳,再对所得胶乳进行氨化剪切,制备了聚合物含量约32%、乳化剂量约1.2%、粘度约220cP、数均粒径63nm的丙烯酸酯超微胶乳。单体两段滴加法中,当预加单体小于30%时,聚合反应体系具有很好的稳定性。氨化剪切阶段,加氨4ml、剪切5min时微化效果最佳。此外,超微胶乳涂膜的性能与单体配比、加氨量和剪切时间都有关。将常规乳液聚合制得的乳液在一定条件下加氨搅拌微化,制备了乳化剂量为0.6%、固含量为27%且数均粒径在40nm左右的苯丙超微胶乳。氨化温度是影响超微胶乳性能的主要因素,最佳氨化温度为60℃。功能单体丙烯酸（AA）和甲基丙烯酸羟乙酯（HEMA）配合使用,超微胶乳涂膜的硬度和附着力都得到提高。乳化剂用量对超微胶乳及其涂膜的性能也有直接的影响。比较了几种改进的微乳液聚合工艺,采用单体完全滴加法制备了聚合物含量高达33.5%、固含量为38.4%、数均粒径为64.7nm的丙烯酸酯超微胶乳。在较佳反应条件的基础上,改变引发剂的用量对粒径的影响不大。聚合温度以78℃为佳,并且在聚合过程中温度需保持恒定。固含量增加,超微胶乳的粒径、涂膜的硬度及附着力有所增大。以AIBN/CuCl₂/bpy为引发催化配位体系引发苯乙烯微乳液聚合,发现聚合过程中M_n随转化率的提高而下降,PDI随转化率的提高呈增加趋势,常规自由基聚合与ATRP聚合同时存在,反应中后期聚合的可控性逐渐增强。提高CuCl₂、AIBN/CuCl2/bpy浓度,聚合速度下降,聚合的可控性增强,并有Rp∝[CuCl₂]^-0.52和Rp∝[ATRP]^-0.77。CuCl₂/bpy浓度较高时,聚合后期表现出比较明显的活性聚合特征。此外,ATRP微乳液体系在室温下就能顺利聚合,且聚合速度随温度的提高而提高,反应总活化能为67.53kJ/mol。更多还原

【Abstract】 With the development of society and the increasing consciousness in environmental protection, micro-latexes are getting more and more important. The application of micro-latexes will be broadened if the molecular weight is controlled and the molecular weight distribution is narrow. In this thesis, polyacrylate micro-latex and poly（styrene-acrylate） micro-latex with higher solid content and low emulsifier content were prepared by emulsion polymerization followed with ammonification and micronization or by microemulsion polymerization directly. Meanwhile, the initiator-catalyst-ligand system of atom transfer radical polymerization （ATRP） was introduced into microemulsion. The controllability and the kinetics of styrene polymerization in microemulsions with AIBN/CuCl₂/bpy were investigated.Polyacrylate latex was synthesized by two-stage monomer dropping method in emulsion system, and then the micro-latex with 32% polymer, 1.2% emulsifier, 220cP viscosity and small particle size （63nm） was prepared under shearing in the presence of ammonia. When the pre-added monomers were less than 30%, the polymerization could proceed stably. The micronization effect was found best when ammonification with 4ml ammonia and shearing 5min. The performance of micro-latex membrane was affected by the monomer ratio, the amount of ammonia and shearing time.Poly（styrene-acrylate） micro-latex with 0.6% emulsifier content, 27% solid content and number average particle diameter about 40nm was prepared by stirring the normal latex, which was synthesized in conventional emulsion polymerization, in the presence of ammonia. Ammonification temperature was important and 60℃was optimal. The hardness and adhesion of micro-latex membrane increased when combining acrylic acid with hydroxyethyl methacrylate. The content of emulsifier also affected the performance of micro-latex and its membrane.Several kinds of improved microemulsion polymerization technology were compared, and the polyacrylate micro-latex with 33.4% polymer content, 38.4% solid content and number average particle diameter 64.7nm was prepared by continuously feeding of monomer during polymerization. On the basis of optimal polymerization conditions, the amount of initiator affected the particle size of micro-latex only slightly.更多还原