A multi-step synthesis strategy combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening metathesis polymerization (ROMP) yielded a new route to co-continuous materials with phase-separated poly(norbornene) and poly(acrylate) domains. Rapid ring-opening of macromonomers with highly functionalized (&gt;95%) end-groups was observed, on the time scale of less than five minutes. Systematic changes to the norbornene: crosslinker ratio (4:1 to 0.25:1), macromonomer weight percent (20-50%), and degree of polymerization (25-300) led to tunable glass-transition behavior and morphologies (1 or 2 phases). The synthesis parameters were shown to produce interconnected spherical-like domains on the scale of ~2-10 microns, as shown by scanning electron microscopy. Room-temperature acidic conditions were found to dually etch the poly(acrylate) domain, at sites of ester bonds as well as polymer side-chain groups, while largely preserving the poly(norbornene) domain, as evidenced by spectroscopy, calorimetry, microscopy, and thermogravimetric analysis. Finally, we determined which phase-separated materials can be etched to produce macroporous networks. This work expands upon the current available chemistries for making polymerization-induced, phase-separated networks with macroscale features.

Co-continuous polymer networks with tailorable morphologies via ROMP-induced macrophase separation

ACS Spring Meeting 2021

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