UC Irvine

Precision control via molecular structure over adaptive conjugated polymer properties in aqueous environments is critical for realizing their biomedical applications. Here, we unravel the dependence of amphiphilic peptide-polydiacetylene (PDA) conjugate properties on the characteristic steric and hydrophobic contributions within peptide segments that serve as a biomimetic template for diacetylene polymerization in water. We investigated the functional impacts of molecular volume and polarity changes brought by dipeptide substitution domains on the following peptide-PDA material properties at multiple length scales: supramolecular assembly behavior, chain conformation-dependent photophysical properties, cell-material interfacing, and for the first time, bulk electrical properties of their films processed in water. A library of peptide-PDAs with systematically varied sequences show that the contributions of steric effects predominantly influence the electronic structure and resulting trends in photophysical properties, while the interplay between size and hydrophobicity of individual residues becomes more significant for higher-order assemblies affecting bulk properties. This work demonstrates sequence-tunable molecular volume and polarity as synthetic handles to rationally modulate PDA material properties across length scales, providing insights into the programmability of biomimetic conjugated polymers with adaptive functionalities.