Hossain Md Daloar, Kim Won Soo, Hwang Ha Soo, Lim Kwon Taek
Division of Image and Information Engineering, Pukyong National University, San 100 Yongdang-dong, Nam-gu, Busan 608-739, Republic of Korea.
J Colloid Interface Sci. 2009 Aug 15;336(2):443-8. doi: 10.1016/j.jcis.2009.04.044. Epub 2009 Apr 21.
Poly(methylmethacrylate) (PMMA)/montmorillonite clay nanocomposites were synthesized via the free radical polymerization of MMA in the presence of alkyl ammonium substituted polysilsesquioxane surfactant-modified clay and AIBN initiator in supercritical CO(2) and ethanol. The reactions were also conducted by adding a small amount of water to observe the intercalation and exfoliation behavior of the clay and the properties of the nanocomposites. Initially, clay was cation exchanged with the surfactant to enhance its hydrophobicity and to expand the interlamellar spaces of silicate platelets. Organophilization with the three dimensional surfactant and a small amount of water molecules in the solvent reduced the surface energy of clay dramatically, which promoted the miscibility of polymer/clay nanocomposites. The morphology of the nanocomposites was characterized by scanning electron microscopy. The intercalation and dispersion of the clay were quantified by both X-ray diffraction and transmission electron microscopy. Due to the three dimensional structure, alkyl ammonium substituted polysilsesquioxane surfactant gives stable clay separation and dimension stability of the nanocomposites. Different distribution of the clay also plays an important role in physical properties. Thermogravimetric analysis and differential scanning calorimetry were employed to investigate the thermal properties and glass transition temperature of the nanocomposites.
聚甲基丙烯酸甲酯（PMMA）/蒙脱土纳米复合材料是在超临界二氧化碳和乙醇中，以烷基铵取代的聚倍半硅氧烷表面活性剂改性的粘土和偶氮二异丁腈引发剂为条件，通过甲基丙烯酸甲酯的自由基聚合反应合成的。反应还通过添加少量水来进行，以观察粘土的插层和剥离行为以及纳米复合材料的性能。最初，粘土与表面活性剂进行阳离子交换，以增强其疏水性并扩大硅酸盐片层的层间间距。在溶剂中用三维表面活性剂和少量水分子进行有机化处理，显著降低了粘土的表面能，这促进了聚合物/粘土纳米复合材料的混溶性。通过扫描电子显微镜对纳米复合材料的形态进行了表征。通过X射线衍射和透射电子显微镜对粘土的插层和分散进行了定量分析。由于三维结构，烷基铵取代的聚倍半硅氧烷表面活性剂使纳米复合材料具有稳定的粘土分离和尺寸稳定性。粘土的不同分布对物理性能也起着重要作用。采用热重分析和差示扫描量热法研究了纳米复合材料的热性能和玻璃化转变温度。
