Towards bio-inspired polymer adhesives: Activation assisted via HOBt for grafting of dopamine onto poly(acrylic acid)

The design of bio-inspired polymers has long been an area of intense study, however applications to the design of concrete admixtures for improved materials performance have been relatively unexplored. In this work we functionalized poly(acrylic acid) (PAA), a simple analogue to polycarboxylate ether admixtures in concrete, with dopamine to form a catechol-bearing polymer (PAA-g-DA). Synthetic routes utilizing hydroxybenzotriazole (HOBt) as an activating agent were examined for their ability in grafting dopamine to the PAA backbone. Previous literature using the traditional coupling reagent 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) to graft dopamine to PAA were found to be inconsistent and the sensitivity of EDC coupling reactions necessitated a search for an alternative. Additionally, HOBt allowed for greater control over percent functionalization of the backbone, is a simple, robust reaction, and showed potential for scalability. This finding also represents a novel synthet...