The goal of this study is to demonstrate the effect of side chains on the formation and mechanical properties of physically cross-linked networks. For this purpose, a series of ABA triblock bottlebrush with amorphous poly(n-butyl acrylate) (PnBA) bottlebrushes as central B blocks and crystallizable poly(octadecyl acrylate-stat-docosyl acrylate) (poly(ODA-stat-DA)) as A blocks were synthesized. These materials were used to generate a series of reversible physical networks with bottlebrush strands bridging crystalline cross-links, which displayed very low moduli of elasticity of the order of 103 −104 Pa. Densely grafted amorphous PnBA side chains are crucial for the extremely low moduli because such architecture facilitates disentanglement of the network strands and suppresses the formation of percolation in the crystalline phase formed by crystallization of the linear-chain tails. In this work, we showed that the cross-link density could be effectively controlled by the DP of the side chains. Shorter side chains allowed the association between crystallizable tails of neighboring bottlebrushes, while steric repulsion between longer side chains prevented network formation because of hindered phase separation and crystallization process.

Supersoft networks based on crystalline triblock molecular bottlebrushes

254th National Meeting (2017)

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