Morphology, dynamic mechanical properties, and gas separation of crosslinking silica‐containing polyimide nanocomposite thin film

Silica‐containing polyimide (PI‐Si) crosslinked hybrid films are synthesized and applied to gas separation application. The PI‐Si hybrid films are prepared from 4,4′‐diaminodiphenyl ether (ODA), 3, 3′‐oxydiphthalic anhydride (ODPA), p‐aminophenyltrimethoxysilane (APTS), and phenyltrimetoxysilane (PTS). The monomer of monoamide APTS is used to modulate the block chain length of ODA–ODPA and then form bonding between PTS and ODA–ODPA phases. In the series of xASPI (where x indicates the molecular weight (in kg/mol) of PI block chain length of ODA–ODPA and ASPI denotes PI modified with APTS) hybrid films, the glass transition temperature (Tg) increases and α‐relaxation damping peak intensity decreases with the increase of APTS content. Meanwhile, the gas permeabilities of O2 and N2 of xASPI films are slightly higher as compared with pure PI. The other series of (5AS–y‐S)PI (5ASPI incorporates with PTS and y is the weight of PTS) hybrid films, the properties of Tg, density, and α‐relaxation damping peak intensity are decreased with increasing the PTS content. However, higher O2 and N2 gas permeabilities and O2/N2 selectivity are achieved by increasing the PTS content in (5AS–y‐S)PI hybrid films.