Visualization of interfacial urethane polymerizations by means of a new microstage reactor

Mixing activated polymerizations, such as RIM urethane polymerizations, may evolve from an imperfectly mixed state; this can drastically modify the characteristics of the polymer formed. Here we focus on the basic building block of the unmixed state: a single interface between reactive monomers. We present a reactor which allows the visualization of the inerface by using an optical microscope and use it to document a variety of phenomena for two and three component urethane polymerizations: (1) the interface may or may not be stable, producing fingering, roll cells, or spontaneous generation of interfacial area, (2) different types of domains (e.g. crystalline or phase-separated) may be formed on opposite sides of the interface, and (3) hard and soft domains may be segregated for the three component polymerization due to diffusional effects.