SiO_2表面接枝聚离子液体及其在聚苯乙烯超临界二氧化碳发泡中的应用

Synthesis of the Silica Particles Grafted with Poly(ionic liquid) and its Application in Polystyrene Supercritical Carbon Dioxide Foaming

采用原子转移自由基聚合法(ATRP)在二氧化硅(SiO2)表面接枝具有二氧化碳(CO2)强吸收能力的聚甲基丙烯酰氧乙基三甲基四氟硼酸铵(P[MATMA][BF4]),再以聚丙烯酸与聚苯乙烯(PS)的嵌段共聚物(PAA-b-PS)为相容剂,将SiO2-P[MATMA][BF4]添加到PS基体中进行超临界CO2发泡,以提高CO2在PS基体中的溶解度及异相成核效率。将氨基改性的SiO2(SiO2-NH2)与PS的复合物作对比。红外光谱(FT-IR)、热重分析(TGA)、透射电镜(TEM)、扫描电镜(SEM)分析结果表明,SiO2表面能够接枝聚离子液体,且SiO2-P[MATMA][BF4]与SiO2-NH2在PS基体中均有良好的分散效果;相比于纯发泡PS,PS/SiO2-NH2复合发泡材料的泡孔结构变化不大,而SiO2-P[MATMA][BF4]的引入,使得发泡PS的泡孔密度显著提高,平均泡孔尺寸明显降低,泡孔尺寸分布变窄。说明SiO2-P[MATMA][BF4]具有更高的异相成核效率。

Poly[2-（methacryloyloxy）ethyl]trimethylammonium tetrafluoroborate（P）,as a novel poly（ionic liquid） with the strong carbon dioxide（CO2） absorption ability,was grafted onto silica particles（SiO2） by using the method of surface-initiated atom transfer radical polymerization（ATRP）.The modified SiO2 was introduced into polystyrene（PS） matrix by the aid of polyacrylic acid and polystyrene diblock copolymer（PAA-b-PS） as compatibilizer,and its influences on PS foaming by supercritical CO2 were investigated.The results of Fourier transform infrared spectroscopy（FT-IR）,thermo-gravimetric analysis（TGA）,and transmission electron microscopy（TEM） show that P could be grafted to the surface of SiO2 by ATRP,and the resultant modified SiO2（SiO2-P） could be well-dispersed in the PS matrix.The SiO2 modified by（3-aminopropyl）triethoxysilane（KH-550）（SiO2-NH2） was also synthesised in the same manner for comparison.The cell morphology characterization obtained by using scanning electron microscopy（SEM） indicates that the morphology of PS/SiO2-NH2 composite foam has no significant difference from that of pure PS foam.However,PS/SiO2-P composite foam possesses higher cell density,smaller cell size and narrower size distribution than those of pure PS foam and PS/SiO2-NH2 composite foam.Compared with SiO2-NH2,SiO2-P exhibits a much higher heterogeneous nucleation efficiency in the foaming process.