Zhang Fen, Bai Yaowen, Ma Yuhong, Yang Wantai
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, P.O. Box 37, Beijing 100029, China.
J Colloid Interface Sci. 2009 Jun 1;334(1):13-21. doi: 10.1016/j.jcis.2009.02.040. Epub 2009 Apr 8.
A novel dispersion polymerization system, with a methanol/water (MeOH/H2O) mixture as reaction medium and a polymerizable dimethylaminomethacrylate methyl chloride (DMC) as stabilizer was developed. By monitoring the polymerization evolution and observing the morphological changes of the polystyrene (PS) particles by SEM, it was found that this system had the following unique features: (1) a much lower amount of DMC (0.025 mass% based on styrene as opposed to 5 mass% for a routine system) was required to prepare monodisperse and stable PS particles; (2) the rate of polymerization was fast and the conversion was very high; (3) the monodisperse particles with average diameters of approximately 200-1600 nm could be directly obtained. These features were explained by a synergistic interaction between water and the quarternary ammonium cations. Combined with XPS, ion-exchange/conductometric titration, FTIR and 1H NMR analysis, a plausible polymerization mechanism through which the particles were stabilized by the PS-PDMC copolymer formed in situ was proposed.
开发了一种新型分散聚合体系，以甲醇/水（MeOH/H₂O）混合物作为反应介质，以可聚合的二甲基氨基甲基丙烯酸甲酯氯（DMC）作为稳定剂。通过监测聚合过程并利用扫描电子显微镜（SEM）观察聚苯乙烯（PS）颗粒的形态变化，发现该体系具有以下独特特征：（1）制备单分散且稳定的PS颗粒所需的DMC量要低得多（基于苯乙烯为0.025质量%，而常规体系为5质量%）；（2）聚合速率快且转化率非常高；（3）可直接获得平均直径约为200 - 1600 nm的单分散颗粒。这些特征通过水与季铵阳离子之间的协同相互作用得到了解释。结合X射线光电子能谱（XPS）、离子交换/电导滴定、傅里叶变换红外光谱（FTIR）和核磁共振氢谱（¹H NMR）分析，提出了一种合理的聚合机理，即通过原位形成的PS - PDMC共聚物使颗粒稳定。
