构建巯基-Ce(Ⅳ)盐氧化还原引发体系实现丙烯腈在硅胶微粒表面的高效接枝聚合

REALIZING HIGHLY EFFECTIVE GRAFT-POLYMERIZATION OF ACRYLONITRILE ON SURFACES OF SILICA GEL PARTICLES BY CONSTRUCTING MERCAPTO GROUP-CERIUM(Ⅳ) SALT REDOX INITIATION SYSTEM

使用偶联剂γ-巯丙基三甲氧基硅烷(MPMS,KH-590),对微米级硅胶微粒进行了表面化学改性,将巯基引入硅胶微粒表面(SiO2-MPMS),构成巯基-Ce(Ⅳ)盐氧化-还原引发体系,探索研究了丙烯腈在硅胶微粒表面的引发接枝聚合,制得了高接枝度(30 g/100g)的接枝微粒SiO2-MPMS-g-PAN.采用红外光谱(FTIR)、扫描电镜(SEM)及热重分析(TGA)等方法对接枝微粒SiO2-MPMS-g-PAN进行了表征.在此基础上,重点研究了主要因素对巯基-Ce(Ⅳ)盐体系引发AN接枝聚合的影响.研究结果表明,类似于羟基-Ce(Ⅳ)盐体系,巯基-Ce(Ⅳ)盐体系也可以有效地引发乙烯基单体在固体微粒表面接枝聚合.与在固体微粒表面引入可聚合双键的"grafting through"接枝聚合法相比,铈盐引发的接枝聚合,由于活性位点居于载体表面,故具有高的接枝度,是一种高效率的表面引发接枝法.为制得高接枝度的接枝微粒SiO2-MPMS-g-PAN,本研究体系适宜的酸浓度为0.25 mol/L;Ce(Ⅳ)盐浓度为5.0×10-3 mol/L;接枝聚合宜在50℃下进行.

Micron-sized silica gel particles were chemically surface-modified with coupling agent KH-590,mercapto groups were introduce onto the surfaces of silica gel particles,and a redox initiation system of mercapto group-cerium（Ⅳ） salt was constructed.On this basis,the highly effective graft-polymerization of acrylonitrile on surfaces of silica gel particles was explored successfully,and the grafted particles SiO2-MPMS-g-PAN with a high grafting degree of 30 g/100g were obtained.The grafted particles SiO2-MPMS-g-PAN were characterized by FTIR,TGA and SEM methods.The effects of the main factors on the graft polymerization of AN were examined.The experimental results show that mercapto group-cerium（Ⅳ） salt system is similar to hydroxyl group-cerium（Ⅳ） salt system,and it can effectively initiate the vinyl monomers to be graft-polymerized on the surfaces of solid particles.As compared with the method of ＂grafting through＂,the graft polymerization initiated by cerium（Ⅳ） salt has the character of high graft efficiency because the active sites lie on the surface of the support,and it is a highly effective method of ＂surface-initiated grafting＂.In order to prepare the grafted particles SiO2-MPMS-g-PAN with high grafting degree in this system,the suitable H＋ concentration should be 0.25 mol/L,and the appropriate cerium（Ⅳ） salt concentration should be 5.0×10-3 mol/L.At the same time,the graft polymerization should be allowed to carry out at 50℃.