【作者】 戚飞飞；

【导师】 詹晓力； 陈丰秋；

【作者基本信息】 浙江大学 ， 化学工程， 2004， 硕士

【摘要】 细乳液聚合是一种新型的聚合方法，具有独特的聚合机理、乳化体系和颗粒特性，已越来越受到人们关注。近年来关于细乳液聚合的研究大多侧重于乙烯类单体的自由基聚合，而有关八甲基环四硅氧烷（D₄）及功能性有机硅单体的离子型细乳液聚合的报道很少。本文以合成用于织物整理的有机硅阳离子型聚合物乳液为背景，成功地实现了阴离子开环细乳液聚合，并分别对该体系D₄单体细乳液的制备及其稳定性、D₄阴离子开环细乳液聚合机理、聚合规律、成核方式及动力学展开了研究。 细乳液聚合成核场所是单体液滴，其液滴尺寸决定聚合机理与乳液稳定性。本文对D₄单体细乳液的制备工艺技术进行了研究，结果表明：助乳化剂的溶解与扩散、乳化剂对单体液滴的覆盖程度、助乳化剂与乳化剂的协同作用、均质化强度对成核方式和细乳液稳定性均有显著影响。通过均质化分散，在少量乳化剂和助乳化剂存在下，制备了窄分布、平均粒径小于100nm的稳定的阳离子型D₄单体细乳液，可用于进一步实现D₄阴离子开环细乳液聚合。 在制备了稳定的单体细乳液基础上，本文开展了对D₄阴离子开环细乳液聚合机理、聚合规律和成核机理的研究。通过聚合速率和粘均分子量随转化率的变化关系提出了D₄阴离子开环细乳液聚合机理；结合机理考察了聚合温度、催化剂浓度和复合乳化剂浓度对聚合动力学的影响；进一步结合粒径分析对成核机理进行探讨，证明该阴离子开环细乳液聚合不同于常规乳液聚合，主要的成核场所为单体液滴。 根据所提出的聚合机理，本文对D₄阴离子开环细乳液聚合反应动力学进行了研究，建立了该体系下的聚合物链数模型、增长速率模型，并通过拟合确定了该反应体系中不同温度下引发、增长和缩合的速率常数和相应的表观活化能。 通过上述研究，本文成功实现了D₄阴离子开环细乳液聚合，制备了稳定的、纯度高、粒径细、分布窄的阳离子有机硅聚合物细乳液。关于细乳液单体 浙江大学硕士学位论文的制备及其稳定性、聚合机理、聚合规律和成核机理所进行的系统探讨，以及对D;阴离子开环细乳液聚合动力学的研究具有显著的应用背景和一定的理论意义，为进一步合成功能性有机硅聚合物细乳液提供了研究与开发依据。更多还原

【Abstract】 As a new technique, miniemulsion polymerization is attracting more and more concerns for its nucleation mechanism, emulsification system and process. Up to the present most researches of miniemulsion polymerization focus on radical reactions while few has been done on D4 anionic ring-opening miniemulsion polymerization. Based on the background of siloxane cationic polymer emulsions used mainly for fabric softening, miniemulsion polymerization of octamethylcyclotetrasiloxane (D4) by anionic ring-opening reaction was achieved in this work. Scientific researches such as the preparation and stability of D4 cationic miniemulsions, reaction mechanism, nucleation mechanism and kinetics of anionic ring-opening miniemulsion polymerization about this system were carried out.As monomer droplet nucleation predominates during the miniemulsion polymerization, the droplet sizes determine both the reaction mechanisms and the stability of miniemulsion. Preparation of D4 cationic miniemulsions were studied. The results indicate that dissolve and diffuse of cosurfactant, coating of droplet covered by surfactant, cooperation between cosurfactant and surfactant, and intensity of homogenize influence the miniemulsion stability remarkably. Some stable D4 miniemulsions with narrow droplet sizes distributions and small average sizes less than 100nm have been synthesized for D4 ring-open anionic miniemulsion polymerization by homogenization under the condition of surfactant and cosurfactant in small amount.After stable monomer miniemulsions had been prepared, anionic ring-opening polymerization of D4 in miniemulsion was studied, including reaction mechanism, polymerization rules and nucleation mechanism. According to the relations of polymerization velocity and viscosity average molecular weight versus conversion, the mechanism of D4 anionic ring-opening polymerization in miniemulsion was developed. Effects of variations on the rate of polymerizationwere investigated, including reaction temperatures, concentrations of catalyst, surfactant and cosurfactant. Different feature ’between miniemulsion polymerization and conventional emulsion polymerization was proved that monomer droplet nucleation predominates during anionic ring-opening miniemulsion polymerization of D4.On the kinetics study preliminarily, the number of polymer chainsmodel - = kl[D4]t -k’cNf and the propagation velocity model were established. Kinetics analysis and computerizedsimulation are in good agreement with a reaction scheme. The apparent rate constants of initiation, propagation and condensation at various temperatures and the corresponding activation energies were determined.In conclusion, some stable polydimethylsiloxane cationic miniemulsions with narrow droplet size distributions and small average sizes were synthesized through D4 anionic ring-opening miniemulsions polymerization. On such a notable industry background, the study on anionic ring-opening miniemulsion polymerization of D4 including preparation and stability of D4 cationic miniemulsions, reaction mechanism, nucleation mechanism of latex particles and kinetics are valuable to the application and development of this polymerization technique.更多还原