Exploiting Feedstock Diversity To Tune the Chemical and Tribological Properties of Lignin-Inspired Polymer Coatings

Biobased polymers present an immense opportunity to design and manufacture new coating materials largely as a result of their feedstock diversity and inherent functionality, yet unraveling the key structure/property relationships inherent in these environmentally friendly systems remains a considerable challenge. A major focus of this work was to develop functional group property design rules for a representative library of lignin-inspired polymers. Of particular interest were the polymers' solubilities, surface energies, and friction coefficients because of their relevance to coatings applications. The structural diversity of our bioinspired library, consisting of various polymers generated from methacrylate-functionalized lignin pyrolysis products, arose the polymer repeat units relative to the methacrylate backbone. from the differing moieties at the para and ortho positions on Polymer compatibilities with organic solvents studied herein increased with greater aliphatic content in the para functionality and decreased with the incorporation of methoxy groups ortho to the polymer backbone. The surface energies of the films followed similar trends between the interaction parameters and the functional group. By linking solvent compatibility to surface energy, it was demonstrated that changes in polar moieties, such as aldehydes and methoxies, have greater effects on solubility, surface energy, and friction than changes in the aliphatic (dispersive) groups. Thus, the target material properties can be understood and tuned through careful consideration of the pendant group functionalities inherent in the bioinspired materials, unlocking enhanced property design for next-generation coatings.