Organic polymer hybrids with silica gel formed by means of the sol-gel method

Abstract

This article describes organic polymer hybrids with silica gels formed by means of the sol-gel method. The incorporation of organic polymers at the level of molecular dispersion into a metal oxide matrix was accomplished by the hydrolysis-condensation of tetraalkoxysilane (orthosilicate ester) in the presence of the appropriate organic polymer.

Especially, organic polymers consisting of amide groups such as poly(2-methyl-2-oxazoline) were found to form molecular hybrids with silica gel through strong hydrogen bonding. The obtained organic-inorganic polymer hybrids were homogeneous and transparent glassy composite materials in a wide range of the contents of organic polymers. The homogeneity of the hybrid may be due to the molecular dispersion of organic polymer in the silica gel matrix, which is ascribed to the formation of hydrogen bonds between the polymer amide group and silanol group of the silica gel. The occurrence of this hydrogen bond was actually supported by FT-IR spectra of hybrids. Organic-inorganic polymer hybrids having chemical bonds at the ends of organic polymer segments were also prepared strating from polyoxazoline silane coupling agents. The water-adsorption properties of these hybrids showed the hydrophilic or amphiphilic modification of the silica gel.

Another interesting material is porous silica gel with controlled-size pores which is prepared by the pyrolysis of the hybrid at a temperature far below the fusing point of silica gel.