Here we describe a fast and convenient method to obtain anisotropic structural foams using frontal polymerization. We fabricated foams by curing mixtures of dicyclopentadiene and a physical blowing agent via frontal ring opening metathesis polymerization (FROMP). The materials were characterized using micro-computed tomography and an image analysis protocol to quantify morphological characteristics including volume fraction and anisotropy. The cellular structure, porosity, and hardness of the foams changed with blowing agent, concentration, and resin viscosity. Finally, we incorporated a cyclic silyl monomer in the resin to render degradability to the foams under acidic conditions. We synthesized two foams with different pore alignment (anisotropy of 0.72 and 0.80) and similar volume fraction and one solid (no voids). Then, we placed the solids in contact with a solution of HCl in cyclopentyl methyl ether (CPME). We observed faster degradation of the foams compared with the solid with no pores, indicating the cellular structure allows a more effective infiltration of the solution. Moreover, the two foams showed similar degradation profiles which indicates that the anisotropy values were not different enough to have an effect in the degradation rate.

Degradable anisotropic foams via frontal polymerization

ACS Spring 2022

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