可控交联聚合的设计

A NOVEL DESIGN OF CONTROLLABLE CROSS-LINKING POLYMERIZATION

用分子链上合有50～200个羟基的聚乙烯醇靖丁醛（PVB）与4，4＇-二苯甲垸二异氰酸酯（MDI）组成了一个交联聚合体系。反应初期首先形成分子链上合有-NCO和-OH基团的预聚聚分子，预聚物分子在溶液中呈无规线团形态，并存在线团内和线团间反应，由于这是一对竞争反应．所以使交联过程得以控制，PVB分子的官能度与MDI用量可以改变分子内和分子间反应的数量，这正是控制交联过程及设计共有有限分子量的可溶性交联大分子所需要的。

Untill now, how macromolecular random coil morphology influences the cross-linking process has been ignored by researchers. In this paper, a cross-linking polymerization system comprising polyvinyl butyral with 50～200 -OH groups on its chain backbone and 4,4＇-diphenylmethane diisocyanate was designed to investigate this issue. Prepolymers with -NCO and -OH groups on the chain were produced at the early stage of the polymerization. The functional degree of PVB and the amount of MDI have different influence on the inner and inter-coil environment therefore, changes in these factors will inevitably change the ratio of intra-to inter-coil reactions. To control these factors is essential to control the cross-linking polymerization process and to synthesize soluble cross-linking macromolecules with a limited molecular weight. In this paper, this issue was addressed detailedly, and the TEM was used to characterize the structure of ICM.