Microporous Thermosetting Film Constructed from Hyperbranched Polyarylate Precursors Containing Rigid Tetrahedral Core: Synthesis, Characterization, and Properties

Abstract

Porous organic thermosetting film with pore size smaller than 20 A was constructed through the self-cross-linking reaction from hyperbranched polyarylate precursors with rigid tetrahedral skeleton. Using hydroquinone diacetate as the A2 monomer and tetrakis(4-carboxyphenyl)silane as the B4 monomer, the hyperbranched polyarylate precursors were successfully synthesized with high yields, during which the gelation process was efficiently suppressed by heterogeneous polycondensation method by means of the elaborate selection of reaction medium. The control of monomer ratio in the polymerization system led to two types of precursors, i.e., mainly carboxyl-terminated hyperbranched polyarylate (CTHP) and mainly acetoxy-terminated hyperbranched polyarylate (ATHP). They had degree of branching values of 0.53−0.69, molecular weights of 10100−34000 g/mol, inherent viscosities of 0.12−0.18 dL/g, and good solubility in the common solvents. The precursor film, obtained by spin coating from the mixture solution of CTHP ...