PREPARATION AND CHARACTERIZATION OF CHLOROMETHYLATED POLYSTYRENE-GRAFTED PARTICLES OF MICRON-SIZED SILICA GEL

Abstract

The grafting polymerization of styrene on micron-sized silica gel particles was performed in solution polymerization system with the manner of "grafting from",and grafting particles PSt/SiO_2 were obtained.Chloromethylation reaction for the polystyrene grafted on silica gel particle surfaces was allowed to be carried out by using a novel chloromethylation reagent,1,4-bis(chloromethoxy)butane(BCMB),and chloromethylated polystyrene-grafted silica gel particles,CMPS/SiO_2,were prepared and these composite particles also can be called as "composite-type chloro-sphere".The grafting degree of PSt/SiO_2 was analyzed with thermaogravimetric analysis(TG),and the morphology of PSt/SiO_2 particles was examined with scanning electron microscope(SEM).The chemical structure and composition of CMPS/SiO_2 particles were characterized using infrared spectrum(FTIR) and Volhard method.The effects of various factors on the chloromethylation reaction of PSt/SiO_2 were mainly examined.The experimental results show that the method for preparing the composite-type chloro-sphere CMPS/SiO_2 in this study not only is environmentally friendly,but also is easy to be controlled.Various factors,such as reaction time,solvents,catalysts and their used amount and the use level of BCMB will influence the preparation of the composite particle CMPS/SiO_2 greatly.The effects of these factors exhibit in two aspects:(1) they affect the chloromethylation degree of CMPS/SiO_2;(2) they inhibit or accelerate the Friedel-Crafts crosslinking reaction between polystyrene macromolecular chains grafted on the surfaces of silica gel particles.The CMPS/SiO_2 with about 16 wt% of chlorine content(based on the grafted polystyrene) can be prepared when the reaction was carried out at room temperature for about 8 h using CH_2Cl_2 as solvent and SnCl_4 as catalyst.