熱塑性聚醚醯亞胺(PEI)-SiO2 奈米複合材料由可溶性PEI 以新穎溶凝膠法(sol-gel)結合四乙氧基矽烷(TEOS)溶液製備而成,PEI 是由間苯二胺(mPDA)及4,4’-(4,4’-二酚氧基異丙基)-二苯甲酸酐(BPADA)合成。偶聯劑用來提高PI 和SiO2之間相容性。此法並與以插層聚合法製備之PEI-粘土奈米複合材料比較,有機粘土是以蒙脫土使用12-胺基十二酸的銨鹽改質。以X-ray 繞射(XRD)及掃描電子顯微鏡(SEM)分析PEI 奈米複合材料中SiO2 或粘土的分散度及尺寸;發現溶凝膠法提供良好互相聯繫或連續相,然而於插層聚合奈米複合材料時粘土則還會分散殘留。雖然PEI-clay 奈米複合材料的熱性質比原來有所改善,但經實際測試顯示當有機粘土含量超過2%時則薄膜變得易碎。藉由溶凝膠法製備PEI 奈米複合材料可以改善熱穩定性和機械性質,SiO2 含量可高達10%,且起始分解溫度為550~600℃。但於較高SiO2 含量時,其機械性質會因為相分離而降低。
Thermoplastic polyetherimide (PEI)-SiO2 nanocomposites were prepared from a soluble PEI, which was synthesized from m-phenylenediamine and bisphenol A dianhydride, in combination with tetraethoxysilane solution via a novel sol-gel process. A coupling agent was used to enhance the compatibility between PEI and silica. This approach was compared with PEI-clay nanocomposite in which montmorillonite was modified with ammonium salts of 12-aminododecanoic acid using an intercalation polymerization. The size and dispersion of the silica or clay in the PEI nanocomposites were analyzed by x-ray diffractometer and scanning electron microscopy. It was found that the sol-gel process offered a fine interconnected or co-continuous phase, whereas the clay remained dispersed in nanocomposites. Though the thermal properties of PEI-clay nanocomposites were improved over pristine PEI, physical testing showed that the films become brittle as the organoclay content increased to over 2%. The thermal stability and mechanical properties of the PEI/silica nanocomposites prepared by sol-gel process were improved with silica content up to 10%. The onset decomposition temperatures were 550-600oC. The dielectric constant decreased with increasing amounts of silica. At higher silica contents, the mechanical properties were reduced as a result of the phase separation.