Versatile Value-added Application of Hyperbranched Lignin Derivatives: Water-resistance Adhesive, UV Protection Coating, Self-healing and Skin-adhesive Sensing

Abstract Bio-based copolymers with versatile properties and good processability are highly desired for practical applications. Herein we describe novel hyperbranched adhesive, UV protective coatings and functional elastomers with 6.1-9.5 wt% lignin synthesized by a one-pot RAFT grafting polymerization. The unique macromolecular structure and sufficient hydrogen bonds of these Lignin-graft-poly(n-butyl acrylate-co-1-vinylimidazole) copolymers (Lignin-BVs) resulted in fascinating and controllable features. Specifically, incorporating 13.9 wt% imidazole (VI) effectively improved the adhesive performances with maximal adhesive force and strength up to 34.0 N and 367.8 N·s, respectively, which were better than the commercial 3M double-sided adhesive. Owing to water-resistance and UV absorption capacity, our Lignin-BVs could be served as excellent adhesive coatings for future outdoor decorative materials, safety clothing or beach umbrella. Moreover, upon increasing VI content to 19.4 wt%, Lignin-BV19.4 elastomer showed automatically room temperature self-healing behavior and could be fabricated into skin-adhesive strain sensor. Our studies provided a green and effective method in the preparation of the high value-added lignin copolymers, which could be appealing to both frontier research and industrial development.