Bespoke polyamides via post-polymerization modification using accessible bioadvantaged monounsaturated long chain fatty acid units

Abstract

Here, we report the copolymerization of a C20:1 monounsaturated long-chain α,ω (MULCH) diacid with polyamide-6,6 (PA66) and polyamide-6 (PA6), and subsequent post-polymerization derivatizations in the swollen or solid state. Surprisingly, most of the unsaturation survived harsh polymerization conditions. The partially unsaturated polyamides were subsequently derivatized through swollen- or solid-state chemistries, including epoxidation and thiol–ene click reactions, demonstrating the opportunity to transform a single nylon/MULCH copolymer into a plethora of high-performance specialty grades through processes like reactive extrusion or chemical washing. Bio-based MULCH diacids could thus serve as a foundation for bespoke polyamides; for example, enabling enhanced water resistance, crosslinkability, recyclability, or internal plasticization. The versatility afforded by MULCH diacid monomers adds significant value, supporting the growth of the bioeconomy. We illustrate these concepts with several examples of modifying MULCH copolymers: chemical staining, enhanced hydrophobicity through grafting of aliphatic pendants, crosslinking, and epoxidation. Chemical and physical properties are evaluated and compared to those of PA66 or PA6 homopolymer controls. Advances in vegetable oil processing and biotechnology have enabled the large-scale production of a variety of MULCH-diacids from lignocellulosic feedstocks. This work illustrates how the “bioadvantage” presented by monounsaturation can be exploited in high-value applications, facilitating the growth of the biobased chemical sector.