Polymer gels formed from crosslinked polymers swollen with solvent are unique soft materials. They display highly tailorable and nonlinear mechanical behavior yet the presence of solvent also leads to dilution of the polymer chain density thus leading to low fracture toughness. In this contribution, we address this limitation by synthesizing soft but solvent-free bottlebrush polymer networks, and then studying their elasticity and fracture behavior. As a robust and versatile synthetic platform, we polymerized mono- and di-norbornene poly(n-butyl acrylate) macromonomer and crosslinker with Grubbs 3rd generation catalyst to achieve bottlebrush networks, and demonstrate control over network properties via systematic variation in the macromonomer to crosslinker ratio. We characterize the elasticity of these materials using compression testing to show the systematic tunability in their shear modulus as well as their entanglement-free nature. Finally, we use a wire cutting fracture test method to quantify their fracture energy and show how this synthetic platform enables the design of soft but tough materials.

Fracture of soft but solvent-free polymer networks

255th National Meeting (2018)

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