Bottlebrush-templated percolation of P3HT and design of tissue mimetic conductive materials

Physical blending is a conventional strategy used to create desired property combinations in composite materials. However, blends of conductive composites are prone to high stiffness and brittleness. Furthermore, even at lower fractions, additives tend to undergo uncontrolled aggregation which precludes percolation. We use coarse-grained molecular dynamics simulations to demonstrate viability of the bottlebrush macromolecules as a template for dispersion and confined aggregation of poly(3-hexylthiophene-2,5-diyl) (P3HT). Our simulations demonstrate that the densely grafted side chains promote segregation of dispersed P3HT molecules within the inter-brush space, providing a kinetically favorable pathway for aggregation of functional moieties. The results of the computer simulations were confirmed by physical blending of thermoplastic elastomers of bottlebrush copolymers with a controlled fraction of P3HT blocks that can attain functional material with percolation threshold at as little as 5 wt % of P3HT and tissue-like mechanical properties. The formation of a percolated P3HT scaffold was confirmed by dynamic mechanical analysis, 4-point conductivity, and transmission electron microscopy (TEM).