构建芳叔胺-BPO氧化还原引发体系实现苯乙烯在硅胶微粒表面的高效接枝聚合

首先使用偶联剂γ-氨丙基三甲氧基硅烷(AMPS)对微米级硅胶微粒进行了表面改性,制得表面带有伯胺基的改性微粒SiO2-AMPS,接着使4-(二乙氨基)水杨醛(DEAS)与微球SiO2-AMPS发生席夫碱反应,制得表面含有芳叔胺基的改性微粒SiO2-DEAS.使改性微粒SiO2-DEAS表面的芳叔胺基团与溶液中的BPO构成氧化-还原引发体系,实现了油溶性单体苯乙烯(St)在硅胶微粒表面的引发接枝聚合,制得了高接枝度(27 g/100g)的接枝微粒SiO2-DEAS-g-PSt.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-DEAS-g-PSt进行了表征.在此基础上,重点研究了主要因素对芳叔胺-BPO体系引发St接枝聚合的影响.研究结果表明,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,芳叔胺-BPO体系引发的接枝聚合,由于活性位点位于载体表面,故具有高的接枝度,是油溶性单体的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-DEAS-g-PSt,适宜的温度为50℃,适宜的BPO用量为单体的3 wt%左右,适宜的单体浓度为10 wt%.

CONSTRUCTING ARYL TERTIARY AMINE-BPO REDOX INITIATION SYSTEM TO REALIZE HIGHLY EFFECTIVE GRAFT-POLYMERIZATION OF STYRENE ON SILICA GEL PARTICLES

Micro-sized silica gel particles were first surface-modified with coupling agent γ-aminopropyltrimethoxysilane(AMPS) for obtaining the modified particles SiO2-AMPS,on which primary amino groups were chemically attached.Subsequently,the Schiff base reaction between SiO2-AMPS particles and 4-(diethylamino)salicylaldehyde(DEAS) was allowed to carried out,resulting in the modified particles SiO2-DEAS,on which aryl tertiary amine moieties were bonded.So a redox initiation system was constituted with the aryl tertiary amine moieties on the surfaces of SiO2-DEAS particles and benzoyl peroxide(BPO) in a solution,and the "surface-initiated grafting" of styrene(St) was realized,and the grafted particles SiO2-DEAS-g-PSt with a high grafting degree of 27 g/100g were prepared.The grafted particles SiO2-DEAS-g-PSt were characterized by FTIR,SEM and TGA.In this work,the effects of some factors on the graft-polymerization of styrene were mainly investigated.The experimental results show that the graft-polymerization initiated by aryl tertiary amine-BPO system has the character of high grafting degree because of the lying of active sites on the surfaces of the support particles as compared with the method of "grafting through",in which the polymerizable double bonds are first introduced onto the surfaces of the solid particles.For those oil-soluble monomers,this is a surface-initiated grafting method with a high efficiency.In order to prepare the grafted particles SiO2-DEAS-g-PSt with a high grafting degree,50℃should be selected as an suitable reaction temperature,a amount of BPO with 3 wt% of the monomer mass should be selected as an appropriate used amount of BPO in the solution,and the applicable monomer concentration is 10 wt% of the solution mass.