Organic‐inorganic polymer hybrids

The present article describes a group of new materials by the combination between organic polymer and silica gel, one of typical inorganic substances. Characteristics of these materials exist in the dimension of blending of the two components, i.e., blending at the molecular level dispersion. The new materials are transparent glassy ones, which are well expressed by a word of “Hybrid”. The hybrids are readily prepared by the sol‐gel reaction of Si(OEt)4, the precursor of silica gel, in the presence of an organic polymer which consists of a repeating unit containing ‐N(R)‐C(=O)‐ group (R=hydrogen or alkyl), i.e., N‐alkyl or N,N‐dialkyl substituted carboxyl amide, urea and urethane groups. Hydrogen‐bond between the above group of organic polymer component and silanol group which is a key intermediate of the sol‐gel reaction plays an important role to form a homogeneous transparent material. The formation of hydrogen bond has been established by FT‐IR spectrum, i.e., the shift of vC=O absorption. Calcination of the transparent hybrid produces another interesting material of highly porous silica gel. At a higher temperature, e.g. 600°C, the organic polymer is decomposed but the framework of silica gel remains unchanged. Thus, the space which organic polymer occupies becomes a pore. The new porous silica gel is characterized by a high surface area of inner surface (∼ 810 m2/g) and a pore size of diameter around 20 Å.