Interfacial reaction-induced roughening in reactive polymer blends

Reactive blending of immiscible polymers is an important process for synthesizing polymer alloys with superior properties. Polymers with reactive end groups are processed to generate copolymer at the interface, which compatibilizes the blend. Interfaces between the reacting polymers have been observed to roughen spontaneously, resulting in a microemulsion. We quantify the onset of interfacial roughening in reactive polymer blends in a layered geometry, using a phase-field model. We study this phenomenon for different interface shapes, layer thicknesses, and reaction rates specified by a Damkohler number (Da_f), under static conditions. For a fixed Da_f, the reaction conversion and microstructure of systems with layers of same thickness evolve similarly. The conversion and the onset of roughening is slower for systems with thicker layers, and those specified by a smaller Da_f. We also show that weak thermal fluctuations accelerate the conversion, leading to a faster onset of interfacial roughening.