采用巯基-BPO氧化还原引发体系实现GMA在硅胶微粒表面的高效接枝聚合

Constructing mercapto-BPO redox initiation sysetm to realize effective graft-polymerization of GMA on silica gel particles

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,制得了表面带有巯基的改性微粒MPMS-SiO2.使改性微粒MPMS-SiO2表面的巯基与溶液中的BPO构成氧化-还原引发体系,实现了油溶性单体甲基丙烯酸缩水甘油酯(GMA)在硅胶微粒表面的引发接枝聚合,制得了接枝度为26g/100g的接枝微粒PGMA/SiO2.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PGMA/SiO2进行了表征。在此基础上,重点研究了主要因素对巯基-BPO体系引发GMA接枝聚合的影响.研究结果表明,巯基-BPO体系引发的接枝聚合,由于活性位点位于固体表面,因此也是一种表面引发接枝法。与在固体微粒表面引入可聚合双键的"穿过接枝"("grafting through")法相比,巯基-BPO引发体系可更有效地实现油溶性单体的接枝聚合.为制得高接枝度的接枝微粒PGMA/SiO2,适宜的温度为55℃,适宜的BPO用量为单体的1wt%左右,适宜的单体浓度为10 wt%。

Micro-sized silica gel particles were first surface-modified with coupling agent y-mercaptopropyl trimethoxysilane （MPMS） , obtaining the modified particles MPMS-SiOz, on which mereapto groups were chemically introduced. Subsequently, A red-ox initiation system was constituted with the mercapto groups on the surfaces of MPMS-SiO2 particles and benzoyl peroxide（BPO） in a solution, and the＂ surface-initiated graft-polymerization＂ of glycidyl methacrylate （GMA） was realized, achieving the grafted parti- Cles PGMA/SiO2 with a high grafting degree of 26g/100g. The grafted particles PGMA/SiO2 were characterized by FTIR,SEM and TGA. In this work, the effects of the main factors on the graft-polymerization of GMA were mainly investigated, and the graft-poly- merization mechanism was explored. The experimental results show that as compared with the method of＂ grafting through＂ ,in which the polymerizable double bonds are first introduced onto the solid particles, the graft-polymerization initiated by mercapto-BPO sys- tem has the character of high grafting degree because of the locating of active sites on the surface of the support. For those oil-solu- ble monomers,this is a surface-initiated grafting method with a high efficiency. In order to prepare the grafted particles PGMA/SiO2 with a high grafting degree,55℃should be selected as a suitable reaction temperature, the used amount of BPO in the solution should be selected as of 1 wt%, and the appropriate monomer concentration is 10 wt% of the solution mass.