Tropoelastin-Inspired, Non-Ionic, Self-Coacervating Polyesters as Strong Underwater Adhesives

Abstract

Inspired from the one-component self-coacervation of tropoelastin and mussel foot protein-3s, we created the first non-ionic, single component coacervates that can coacervate in a all ranges of pH (acidic to basic) and wide range of ionic strengths with degradability, rapid curing and strong underwater adhesion. In contrast to the complex coacervates, these ‘charge-free’ coacervates are potential candidates as tissue adhesives and sealants, adhesives for sensor attachment to wet skin, and as sprayable adhesives. Their potential use in the clinic arises from their enhanced stability to changes in external conditions, cytocompatibility, biodegradability and modular nature in incorporating various functional groups and crosslinkers.

Rational design of adhesives for effective underwater bonding

“…When the temperature of water environment was elevated higher than the lower critical solution temperature of PNIPAM, this adhesive can transform to non-flowing hydrogels underwater. In addition, the covalent crosslinking that happened within the coacervate, such as the oxidation of catechol groups-induced crosslinking (Shao and Stewart, 2010), azentidinium-induced crosslinking in base condition or over long time (Wei et al, 2019;Zhu et al, 2019; and [2 + 2] cycloaddition reaction of coumarincan-induced crosslinking (Narayanan et al, 2020) also result in the curing of the coacervate-based adhesives. For these coacervate-based adhesives, the underwater adhesive strength was often higher than those of uncured coacervate-based adhesive, probably due to their stronger cohesiveness.…”