Poly[2-(methacryloyloxy)ethyl]trimethylammonium tetrafluoroborate (P[MATMA][BF4]), 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[MATMA][BF4] could be grafted to the surface of SiO2 by ATRP, and the resultant modified SiO2 (SiO2-P[MATMA][BF4]) 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[MATMA][BF4] 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[MATMA][BF4] exhibits a much higher heterogeneous nucleation efficiency in the foaming process.%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.
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