摘要
先使用偶联剂γ-巯丙基三甲氧基硅烷(MPMS)对微米级硅胶微粒进行了表面改性,然后使改性微粒表面的巯基与溶液中的偶氮二异丁腈(AIBN)构成巯基-AIBN引发体系,引发油溶性单体甲基丙烯酸缩水甘油酯(GMA)在硅胶微粒表面发生接枝聚合,制得了高接枝度(23g/100g)的接枝微粒PGMA-SiO2。对影响GMA接枝聚合的主要因素进行了考察,对表面引发接枝聚合的机理进行了研究。以对氨基苯磺酸钠为试剂,通过环氧基团的开环反应,对PGMA-SiO2接枝微粒进行了功能化改性,将阴离子基团苯磺酸钠(BSNa)键合于接枝大分子PGMA侧链,制得功能接枝微粒BSNa-PGMA-SiO2,并初步研究了其功能性。研究表明,受溶液中的AIBN分解反应的诱导,改性硅胶微粒表面的巯基会发生氢原子转移,在硅胶微粒表面产生硫自由基,使GMA可在硅胶微粒表面有效地发生接枝聚合。接枝聚合适宜的温度为55℃,适宜的AIBN用量为单体质量的0.8%。功能接枝微粒BSNa-PGMA-SiO2表面携带有高密度的负电荷,对苦参碱和金雀花碱等生物碱分子具有强吸附作用。
Micro-sized silica gel particles were first surface-modified with coupling agent γ-mercaptopro- pyltrimethoxysilane （MPMS）, obtaining the modified particles MPMS-SiO2, on which thiol groups were chemically attached. Subsequently, a surface-initiating system was constituted with the thiol groups on the surfaces of MPMS-SiO2 particles and 2,2%azobis （2-methylpropionitrile） （AIBN） in the organic solvent, namely the thiol-AIBN initiating system was formed. The ＂surface-initiated graft-polymerization＂ of glyci- dyl methacrylate （GMA） was carried out, preparing the grafted particles PGMA-SiO2 with a high grafting degree of 23 g/100 g. The effects of the main factors on the graft-polymerization of GMA were examined, and the mechanism of the surface-initiated graft-polymerization was explored. The functional modification of the grafted particles was conducted using sodium 4-aminobenzenesulfonate as reagent via the ring-opening reaction of the epoxy groups of the grafted PGMA, obtaining the functional particles BSNa-PGMA- SiO2 on which sodium benzenesulfonate （BSNa） groups were bonded, and their functionality was prelimi- narily investigated. Results show that by inducing the decomposition reaction of AIBN, the thiol groups onthe surfaces of the particles MPMS-SiO2 will produce a hydrogen atom transfer process from thiol groups to the free radicals that were the product of the decomposition reaction of AIBN. As a result, a great deal of sulfur free radicals will produce on the surfaces of silica gel particles, and they will effectively initiate the monomer GMA to be graft-polymerized onto silica gel particles. For the graft-polymerization system, 55 ℃ should be selected as a suitable reaction temperature, and an amount of AIBN with 0. 8% of the monomer mass should be selected as an appropriate used amount of AIBN in the solution. The functional particles BSNa-PGMA-SiO2 carry negative charge with a high density because of the presence of anionic polyelectrolyte on their surfaces. By right of strong electrostatic interaction, the functional particles BSNa PGMA-SiO2 possess strong adsorption ability towards alkaloids such as for matrine and cytisine.
出处
《功能高分子学报》
CAS
CSCD
北大核心
2013年第3期223-230,共8页
Journal of Functional Polymers
基金
山西省青年科学基金资助项目(20110210215)
关键词
表面引发接枝
甲基丙烯酸缩水甘油酯
硅胶
巯基
氢原子转移
surface-initiated graft-polymerization
gtycidyl methacrylate
silica gel
thiol
hydrogen atomtransfer
