水性可紫外光固化的硫代聚氨酯分散体的制备

Preparation of UV-curable Waterborne Polythiourethane

本文利用巯基-点击化学制备了一系列水性可光固化的硫代聚氨酯分散体,即通过连续的巯基-异氰酸酯和巯基-迈克尔加成反应分别合成硫代聚氨酯和聚硫醚:首先,二异氰酸酯与过量的二元硫醇反应生成端基为巯基的硫代聚氨酯低聚物,然后与合成的二丙烯酸酯单甲基丙烯酸酯进行巯基-迈克尔加成反应,得到侧基为甲基丙烯酸酯的硫代聚氨酯树脂,最后,巯基乙酸与端基上的丙烯酸酯反应,提供树脂的亲水基团。将树脂分散在水中后,得到半透明的可光固化硫代聚氨酯分散体。树脂的主链上含有硫醚键,可以有效克服氧阻聚效应,得到较高的转化率;侧基上带有很多可光聚合的甲基丙烯酸酯基团,光聚合后固化膜的交联密度非常高,因而也具有较高的玻璃化转变温度。

A series of UV-curable waterborne polythiourethane dispersions were successfully prepared via sequential thiol-click reactions.Speciffically,thiol-isocyanate and thiol-Michael reactions were implemented,and the overall two-step procedure efficiently yielded desired product under mild reaction conditions.Initially,diisocyanate and excess dithiol were reacted to produce the oligomeric polythiourethane dithiol,which was afterwards selectively reacted with acrylate groups of glicerol-derived diacrylate-monomethacrylate monomer to provide the resin containing methacrylate functionalities along the polythiourethane backbone.After the resin was dispersed in water,what resulted in translucent emulsion,the UV-curable waterborne polythiourethane was obtained.As a significant amount of methacrylate groups were attached on the main polymer chains,a dramatical increase in the crosslink density of films was achieved after UV-curing.The resultant crosslinked materials exhibited excellent mechanical properties thus showing promise for coatings applications.