热敏乳液薄膜的制备及性能

本文介绍了一种可以通过三步法制得的具有亲油的核和亲水的壳的高分子微胶粒。首先,通过乳液聚合得到甲基丙烯酸正丁酯与甲基丙酸甲酯的共聚物乳液(p-(BMA-MMA));利用(p-(BMA-MMA)乳液作为种子,用一种氧化还原引发体系引发反应,通过控制反应条件,在乳胶粒表面包覆一层均匀的聚甲基丙烯酸缩水甘油酯(p-GMA)外壳,壳层聚合物的含量为5~15wt.%之间;最后,壳层表面的环氧基团与三乙醇胺盐酸盐反应,环氧基团转变为季铵盐,使外壳成为极性的亲水表面。核-壳型固体微胶粒可以在水中较好地分散并形成稳定的乳液。通过旋涂法将固体乳液颗粒和PVA的混合水溶液涂在铝版基上,室温下干燥,可得到乳液薄膜。实验发现,室温下核-壳乳液薄膜与水的接触角在16.1°-27.5°范围内,可经过150℃短时间的烤版处理后,接触角将超过87,°表明乳液薄膜通过加热后完全由亲水性转为亲油性。同时,该乳液薄膜在烤版前很容易用中性水由版基上冲洗掉,但烤版后不再能够被洗掉。当在乳液薄膜中加入一种红外染料(最大吸收波长在830nm)后,该薄膜变得对830nm的LD激光敏感,并通过LD激光曝光和中性水显影后,得到阴图型图像。

Preparation and Properties of Thermo-sensitive Latex Films

Polymer particles with hydrophobic core and hydrophilic shell were prepared via a three-step method.First,poly(butyl methacrylate.co-methyl methacrylate)(p-(BMA-MMA)) latex was prepared through emulsion polymerization.Then,using the p-(BMA-MMA) latex as seed,a uniform shell of poly(glycidyl methacrylate)(p-GMA) was formed by using a redox initiation system under kinetically controlled conditions.The contents of the shell were in the range of 5wt%~15 wt %.Finally,the epoxy groups existing in the shell were converted into the ionic species through the reaction with triethanolamine hydrochlorid in aqueous phase,resulting in a charged hydrophilic shell.The solid particles could be re-dispersed in water to afford a stable emulsion.Latex films were prepared by spin-casting the aqueous mixture of the latex made from the solid latex particles and poly(vinyl alcohol)(PVA) onto an aluminum substrate and then dried at room temperature.The contact angles between the core-shell latex films and water were in the range of 16.1°~27.5 ° at 25 ℃,but would turn to be larger than 87° after the films were baked at 150℃ for a short period of time.This indicated that the films were completely switched from hydrophilicity to hydrophobicity by the action of heat.Additionally,the latex films before baking could be easily washed away from the substrate with neutral water,but could no longer be removed after baking.When an IR dye(with maximal absorption at 830nm) was incorporated into the film,the film became sensitive to LD lasers emitting at 830 nm and negative images were obtained after exposed by LD laser and developed by neutral water.