粒径可控的聚乙烯醇交联微球VA/DVB的制备

Preparation of Crosslinked Polyvinyl Alcohol Microspheres VA/DVB with Controllable Grain Size

以醋酸乙烯酯(VAc)为主单体,二乙烯基苯(DVB)为交联剂,聚乙烯醇(PVA)为分散剂,采用悬浮聚合法制备了交联微球VAc/DVB。重点考察了分散剂用量、搅拌速率、油水两相比例、NaCl用量等因素对交联微球的形成及其粒度的影响。使用甲醇对微球VAc/DVB进行醇解反应,制得了聚乙烯醇交联微球VA/DVB。结果表明:交联微球VA/DVB的物理形态决定于前驱体微球VAc/DVB的形貌与粒径。在悬浮聚合体系中,分散剂用量、搅拌速率与油水两相比是影响交联微球制备的主要因素,当分散剂用量太少(<0.3%)、搅拌速率太慢(<200 r/min)与油水两相体积比太大(>1∶4)时,共聚合体系中均不能发生成球过程。控制悬浮聚合的反应条件,可以制备出球形度好、粒径可调控的交联微球VA/DVB。影响醇解反应的主要因素是反应温度,适宜的温度是40℃,反应15 h醇解度可达92%。

Crosslinked copolymer microspheres VAc/DVB were prepared with suspension polymerization method by using vinyl acetate as a main monomer, divinyl benzene as crosslinker and polyvinyl alcohol as disperser. Effects of various factors, such as the amount of disperser, stirring rate, ratio of oil phase to water phase and the amount of NaCl, on the sphericity and size of the crosslinked microspheres were mainly examined. The alcoholysis of the microspheres VAc/DVB were performed, and the crosslinked polyvinyl alcohol microspheres were obtained. Results show that the physical aspect of the microspheres VA/ DVB dependes on the morphology and grain size of the precursor microspheres VAe/DVB. In the suspension polymerization, the main factors are the amount of the disperser PVA, stirring rate and the ratio of oil phase to water phase. The balling spheres can not be formed as the amount of PVA is 0. 3% less, or the stirring rate is lower than 200 r/min, or the volume ratio of oil phase to water phase is greater than 1 = 4. As long as controlling conditions of the suspension copolymerization, the microspheres VA/DVB with excellent sphericity and controlled particle diameter can be gained. Reaction temperature is the key factor effecting the alcoholysis degree of VA/DVB. The fitting temperature is 40 ℃ and an alcoholysis degree of 92G in 15 h can be reached.