A facile pathway to polyurea nanofiber fabrication and polymer morphology control in copolymerization of oxydianiline and toluene diisocyanate in acetone

Abstract

Precipitation polymerization of toluene diisocyanate and 4,4′-oxydianiline was carried out in acetone. At 1.0 wt% monomer concentration and 30 °C as the polymerization temperature, polymers of different morphologies were obtained depending on the ways of agitation. Under mechanical stirring, a rope-form polymer was obtained at low stirring rate and an aggregate of granular polymers was observed with a stirring rate of 600 r per min or higher; whereas polymer nanofibers were observed with quiescent polymerization and reciprocating shaking. Under quiescent polymerization with a monomer concentration of 1.0 wt%, the influence of the polymerization temperature on the morphology of the polymer was studied. It was found that spherical particles were formed at 0 °C, whereas fibrous polyurea was observed at 30 °C or higher. Studies on the influence of the monomer concentration at 30 °C revealed that nanofibers were obtained at 2.0 wt% of monomer concentration or lower; and spherical particles were formed with higher monomer concentration. The basic properties of the polymers were characterized. This paper provides a novel and facile pathway to the fabrication of a novel type nanofiber of polyurea based on toluene diisocyanate and 4,4′-oxydianiline.