Microbial pABA Enables Renewable PBA Whiskers with Enhanced Crystallinity, Thermal Stability, and Surface Smoothness via a Biosynthetic Pathway

Abstract The development of fully renewable high-performance aramids has been limited by the absence of biosourced aromatic monomers suitable for A–B type polymerization. Here, we report the synthesis of poly(p-benzamide) (PBA) whiskers derived entirely from microbially produced p-aminobenzoic acid (pABA), achieving 100% biogenic carbon content verified by radiocarbon analysis. The high chemical purity of the biosynthesized monomer enables PBA whisker formation via phase-transition-driven polymerization under conditions identical to those used for conventional petroleum-derived monomers. The resulting bio-based whiskers maintain the same orthogonally oriented single-crystal architecture as their petroleum-derived analogues, while exhibiting slightly higher crystallinity, marginally improved thermal stability, and smoother faceted surfaces. These subtle enhancements may originate from differences in monomer synthesis routes, particularly the reduced impurity levels inherent to microbial production processes. Although these structural refinements do not significantly alter dispersion behavior, they provide a cleaner crystalline morphology advantageous for probing fundamental structure–property relationships. By integrating microbial monomer production with established aramid crystallization pathways, this work demonstrates that complete renewable sourcing can be achieved without compromising material performance, while offering modest improvements linked to biosynthetic monomer origins.