氯甲基聚苯乙烯/硅胶复合微粒的制备与表征

采用"接出(grafting from)"方式,在溶液聚合体系中将苯乙烯(St)接枝聚合在微米级硅胶表面,制备了接枝微粒PSt/SiO2;使用新型氯甲基化试剂1,4-二氯甲氧基丁烷,对接枝在硅胶表面的聚苯乙烯进行了氯甲基化(CM)反应,制得了氯甲基聚苯乙烯/硅胶(CMPS/SiO2)复合微粒.采用热重分析(TG)测定了PSt/SiO2的接枝度,并使用扫描电子显微镜(SEM)观察了其形貌;通过红外光谱法(FTIR)与佛尔哈德分析法表征了CMPS/SiO2的化学结构与组成.重点考察了各种因素对PSt/SiO2氯甲基化反应过程的影响规律.研究结果表明,CMPS/SiO2的制备不仅具有绿色环保的特点,而且反应容易控制.反应时间、溶剂种类与用量、催化剂种类与用量及氯甲基化试剂的用量等因素均会对该复合微粒的制备产生影响,如影响CMPS/SiO2的氯甲基化程度;抑制或促进已接枝的PSt大分子链之间通过Friedel-Crafts反应发生交联.若选用SnCl4为催化剂,以CH2Cl2为溶剂,在室温下反应10 h左右,可制得氯含量接近16 wt%(以接枝的PSt为基准计算)的CMPS/SiO2.

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

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.