Facile, efficient synthesis of a phosphinated hydroxyl diamine and properties of its high-performance poly(hydroxyl imides) and polyimide–SiO2 hybrids

Abstract

A hydroxyl diamine, 1-(4-aminophenyl)-1-(3-hydroxyl-4-aminophenyl)-1-(6-oxido-6H-dibenz<c,e><1,2>oxaphosphorin-6-yl)ethane (1), was prepared via a facile, one-pot procedure. Based on 1, a series of poly(hydroxyl imides) (2a–2e), were prepared in NMP/xylene by solution polymerization, followed by thermal treatment. Experimental data showed that the poly(hydroxyl imides) displayed better thermal properties than the polyimides without hydroxyl groups. Polyimide–SiO₂ hybrids were prepared based on the sol–gel reaction of tetraethoxysilane (TEOS) with 2e, which was prepared from the condensation of 1 and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). The hydroxyl group on the backbone of 2e provided organic–inorganic bonding. Therefore, light-yellow, transparent and flexible polyimide–SiO₂ films with a maximum SiO₂ content of 16 wt% were obtained without the use of a coupling agent. TEM data showed that several nanorods aggregated into a cluster, and the clusters were well dispersed in the polyimide–SiO₂ hybrids. The optical and thermal properties of 2e were significantly improved by the incorporation of silica.