表面引发接枝聚合法制备接枝微粒PHEMA/SiO2及其8-羟基喹啉功能化转变研究

通过用表面引发接枝聚合和高分子反应制备8-羟基喹啉型复合螯合微粒.首先使用γ-氨丙基三甲氧基硅烷(AMPS)对微米级硅胶微粒进行表面改性,制得改性微粒AMPS-SiO2；使改性微粒AMPS-SiO2表面的氨基与溶液中的过硫酸盐构成氧化-还原引发体系,实施了甲基丙烯酸羟乙酯(HEMA)在硅胶微粒表面的高效引发接枝聚合,制得了接枝微粒PHEMA/SiO2.又以5-氯甲基-8-羟基喹啉(CHQ)为试剂,使接枝的PHEMA发生大分子反应,实现了接枝微粒PHEMA/SiO2的8-羟基喹啉功能化转变,制得了复合微粒HQ-PHEMA/SiO2.采用多种手段对两种微粒进行了表征,重点研究了氨基-过硫酸盐表面引发接枝体系的接枝聚合机理,并研究了CHQ与接枝PHEMA的醇羟基之间取代反应的机理,还初步考察了功能微粒HQ-PHEMA/SiO2对重金属离子的螯合吸附性能.研究结果表明,氨基-过硫酸盐表面引发接枝聚合体系具有很高的引发活性,在室温(30℃)即可制得高接枝密度(40 g/100g)的接枝微粒PHEMA/SiO2；CHQ与接枝PHEMA的醇羟基之间的取代反应遵循SN1的反应历程,使用强极性溶剂有利于反应的进行.微粒HQ-PHEMA/SiO2对重金属离子呈现很强的螯合吸附能力,是一种功能复合微粒.

STUDIES ON PREARATION OF GRAFTED PARTICLES OF PHEMA/SiO2 AND THEIR 8-HYDROXYQUINOLINE-FUNCTIONALIZATION TRANSFORM

Micron-sized silica gel particles were surface-modified with coupling agent γ-aminopropyltrimethoxysilane(AMPS),obtaining the modified particles AMPS-SiO2.A redox initiating system was constituted by the amino groups on the surface of AMPS-SiO2 particles and persulfate in the solution,and the surface-initiated graft-polymerization of 2-hydroethyl methacrylate was performed,resulting in the grafted particles PHEMA/SiO2.Subsequently,a polymer reaction of the grafted PHEMA was carried out,and it was the nucleophilic substitution reaction between the hydroxyl group of the grafted PHEMA and the chloromethyl group of 5-chloromethyl-8-hydroxyquinoline(CHQ).As a result,the 8-hydroxyquinoline-functionalization transform of the grafted PHEMA was realized,obtaining the functional composite particles HQ-PHEMA/SiO2.The two kinds of particles were characterized by several methods.In this work,the graft-polymerization mechanism for the amino group-persulfate initiation system was mainly investigated,and the mechanism of the substitution reaction between the hydroxyl group of the grafted PHEMA and the chloromethyl group of CHQ was also explored in depth.Finally,the chelating adsorption property of HQ-PHEMA/SiO2 for heavy metal ions was preliminarily examined.The experimental results show that the amino group-persulfate initiation system has very high initiation activity,and it can effectively initiates the graft-polymerization of HEMA on silica gel particles.At room temperature(30℃),the grafted particles PHEMA/SiO2 with high grafting degree(40 g/100 g) can obtained.The substitution reaction between the hydroxyl groups of the grafted PHEMA and CHQ has a reaction mechanism of SN1,and using the solvent with strong polarity is advantageous to the reaction.The functional particles HQ-PHEMA/SiO2 possess very strong chelating adsorption ability for heavy metal ions.The functional composite particles are promising and potential in the analysis and separation fields.