《悬浮-乳液复合聚合制备核-壳聚合物粒子的研究》由会员分享，可在线阅读，更多相关《悬浮-乳液复合聚合制备核-壳聚合物粒子的研究（104页珍藏版）》请在金锄头文库上搜索。
1、浙 江 大 学 博 士 学 位 论 文 1 摘摘 要要 大粒径(如粒径大于 10m)核-壳结构聚合物复合粒子在溶剂吸附、 药物和 催化剂负载等方面具有良好的应用前景。由于常用的种子乳液和种子分散聚 合只能合成小粒径核-壳聚合物复合粒子， 开发大粒径核-壳结构聚合物复合粒 子的合成方法，并阐明其聚合成粒机理，具有理论和实际意义。 论文首次提出了采用悬浮-乳液复合聚合(SECP)制备大粒径核-壳结构聚 合物复合粒子的新方法，通过在第一单体悬浮聚合过程中，滴加另一单体的 乳液聚合组分(EPC)， 使悬浮聚合和乳液聚合在聚合反应和成粒过程上发生耦 合，控制聚合条件而制得大粒径核-壳结构聚合物复合粒子。
2、论文就 SECP 条 件和第二单体特性对成粒过程的影响、成粒机理、聚合过程粒子组成变化、 聚合动力学和 SECP 的应用进行了研究。 论文以苯乙烯(St)为悬浮聚合单体，滴加含甲基丙烯酸酸甲酯的 EPC， 进行悬浮-乳液复合聚合，考察了形成大粒径聚苯乙烯/聚甲基丙烯酸酸甲酯 (PS/PMMA)核-壳结构复合粒子的主要影响因素。 通过对聚合转化率和聚合物 粒子粒径分布的分析，发现 EPC 滴加策略、EPC 组成和悬浮聚合体系均对粒 子形成有影响，尤其是 EPC 开始滴加时间和滴加方式，是影响形成核-壳结 构大粒径复合粒子的关键因素。 通过追踪 SECP 过程聚合物粒径分布和颗粒形态的变化，发现在
3、 St 悬浮 反应中期滴加 MMA 乳液聚合组分后，聚合体系逐渐由悬浮粒子与乳胶粒子 并存向形成单峰分布的复合粒子转变，最终形成核-壳结构完整的大粒径 PS/PMMA 复合粒子； 在 St 悬浮反应初期滴加 MMA 乳液聚合组分， St 与 MMA 一起分散成更小液滴，反应后期凝并形成非核-壳结构复合粒子；在 St 悬浮反 应后期滴加 MMA 乳液聚合组分，PMMA 乳胶粒子与 PS 悬浮粒子基本独立 存在。在此基础上，提出了悬浮-乳液复合聚合的成粒机理。 研究了第二单体特性对形成的聚合物复合粒子形态的影响，发现滴加水 溶性小、与第一单体聚合物相容性好的第二单体的 EPC，可以在较宽的悬浮 聚
4、合转化率范围内形成核-壳形态完整的聚合物复合粒子， 并且壳/核质量比较 高。以亲水性较强的 MMA 为悬浮聚合单体，滴加含 St 的 EPC，发现同样可 浙 江 大 学 博 士 学 位 论 文 2 以形成核-壳形态完整的复合粒子，并且没有发现 PMMA 和 PS 的相反转。 通过 FTIR、1H-NMR 和 13C-NMR 分析方法，研究 SECP 聚合过程中复 合粒子中 MMA/St 链节摩尔比的变化，发现悬浮粒子中 MMA/St 链节摩尔比 逐渐增大，而 PMMA 乳胶粒子逐渐减少，表明悬浮相和乳液相间存在物质传 递过程。 最终得到的复合粒子除含 PS 和 PMMA 均聚物外， 还含少量
5、MMA-St 共聚物。 St-MMA 悬浮-乳液复合聚合动力学表明，St 聚合转化率时间关系和聚 合速率与悬浮聚合一致； 由于 PMMA 乳胶粒子在悬浮粒子表面的凝并， MMA 聚合速率低于常规乳液聚合速率。分别得到 SECP 和普通乳液聚合恒速段聚 合速率与乳化剂和引发剂浓度的关系为：Rp (SECP)S0.50I0.59， Rp (emulsion)S0.74I0.30。 最后，应用 SECP 方法合成了大粒径丙烯腈(AN)-丙烯酸丁酯(BA)-苯乙 烯(St)共聚(AAS)树脂和 PMMA/聚甲基丙烯酸羟乙酯(PHEMA)复合微球。采 用先滴加含 BA 单体的 EPC，再补加 AN 和
6、St 单体的方法可以合成颗粒形态 良好、St/AN 共聚物接枝率和橡胶含量高的 AAS 树脂，经熔融加工后，橡胶 相在塑料相分散较均匀，制品的力学性能与橡胶含量相近的种子乳液聚合合 成的 AAS 树脂相当。 采用 SECP 方法制备的大粒径 PMMA/PHEMA 复合微球 表面以 HEMA 乳液聚合物为主，且具有微孔结构。复合微球在水和苄醇的平 衡溶胀率大于纯 PMMA 微球。在磷酸盐缓冲液中释放时间长达 360h，释放 量占负载总量的 82%；而 PMMA 微球的释放时间为 216h，释放量占负载总 量的 60%。 关键词：关键词：悬浮-乳液复合聚合；核-壳复合粒子；成粒机理；组成；动力学
7、浙 江 大 学 博 士 学 位 论 文 3 ABSTRACT The core-shell structure polymer composite particles with greater size can be applied in solvent adsorption, drug and catalyzer carrier. Although the synthesis of small size core-shell polymer composite particles via the conventional seeded emulsion polymerization and
8、seeded dispersion polymerization has been widely investigated, the preparation of core-shell structure polymer particles with greater size is still a challenging work. Thus, it is necessary to develop a new method for synthesizing the core-shell polymer composite particles with greater size. An orig
9、inal method, named suspension-emulsion combined polymerization (SECP), was proposed to prepare the core-shell polymer particles with the greater size in this thesis. During the SECP process, the emulsion polymerization constituents (EPC) were added to suspension polymerization (SP) system at the dif
10、ferent stages of suspension polymerization drop-wisely. The suspension polymerization and emulsion polymerization processes would be combined in chemical reaction and particle formation process, and the core-shell polymer composite particles with greater size would be formed by controlling the polym
11、erization conditions. The influences of polymerization conditions and the properties of second monomer on the particle feature, the particle formation process and mechanism, the composition variation of polymer particles, the kinetic of SECP and the application of SECP were investigated. Firstly, SE
12、CP using styrene (St) as the suspension polymerization monomer, and methyl methacrylate (MMA) as the emulsion polymerization monomer, was carried out. It is found that the EPC addition strategy, the constituents of EPC and the features of dispersed droplets in St suspension polymerization system wer
13、e the key factors affecting the formation of core-shell structure particles, and the EPC addition strategy was the most important factor in the formation of core-shell polymer particles. Secondly, the particle features of the resulting polymer particles and the particle 浙 江 大 学 博 士 学 位 论 文 4 formati
14、on mechanism of SECP were studied. It is found that PMMA latex particles were gradually coagulated with PS particles after the addition of EPC at the mid stage of St suspension polymerization, and core-shell structure PS/PMMA composite particles with greater size were finally formed. St/MMA copolyme
15、r particles composed of primary particles and imperfect core-shell structure PS/PMMA composite particles were obtained by adding EPC at the initial and later stage of St SP, respectively. According to the particle formation mechanism of St suspension polymerization and the variations of particle fea
16、tures of PS/PMMA composite particles, the particle formation mechanism of SECP were proposed. The composition of composite polymer particles was analyzed by using FTIR, extraction, 1H-NMR and 13C-NMR methods. It is found that the molar ratio of MMA/St units in composite particles increased and the content of PMMA latex particles decreased with the increasing of polymerization time after the addition of EPC. So, it is evidenced that PMMA latex particles would be coagulated with PS s
