Design of Protein-based Block Copolymer to Reduce Topological Defects in Polymer Networks

Abstract

Biological components and complex structures allow natural tissues and cells to have remarkable properties and functions. When studied individually, proteins have been found to have intriguing and unique mechanical properties at the nanoscale. Interest has increased to create synthetic materials that accurately mimic protein nanomechanics at a macroscopic level, but this poses a challenge because protein-incorporated synthetic materials often do not perform as expected. We hypothesize that decreased performance is due to topological defects in polymer networks. Herein, we designed protein-based block copolymers that are capable of self-association to construct polymer networks. By engineering the mid-block with flexible and rigid protein blocks, we were able to find the optimal ratio between the flexible and rigid blocks, that provide greater network strength, caused by increased effective crosslinking density. Specifically, a mid-block ratio where the contour length of the flexible domain is similar to the length of the tertiary structure of the rigid domain increases the gel strength from about 2.5 kPa when presenting an only flexible mid-block to about 7 kPa, meaning network defects were reduced. This platform for reducing network defects creates a foundation for improving polymer network designs and may allow for increased accuracy in translating protein nanomechanics in synthetic materials.