Bioinspired dopamine-functionalized polymers for enhanced adhesion in construction applications

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). A synthetic route utilizing hydroxybenzotriazole (HOBt) as an activating agent was examined for its ability in grafting dopamine to the PAA backbone. The primary goal of this work was to focus our efforts on incorporating mussel-inspired adhesives for building and construction materials, with an emphasis on concrete. As a wet setting system, DOPA-functionalized polymers may help to strengthen the bond between paste and aggregate, known as the interfacial transition zone (ITZ). The ITZ is important from a structural materials perspective as it represents the weakest point in concrete. We have performed various experiments ranging from modified tensile to peel testing on aggregate substrates and on fresh cement pastes. Furthermore, we have conducted studies on the effect of commercially available additives such as polyethylene glycol towards enhancement of the bio-inspired polymers adhesion strength.