Journal of Rheology, Vol.63, No.3, 391-404, 2019
Small and large amplitude oscillatory shear behavior of supramolecular gels based on dopamine-boronic acid interactions
Blends of polymer solutions of poly(N-isopropylacrylamide-co-dopamine methacrylamide) (NIDO) and poly(N-isopropylacrylamide-co-4-vinylphenylboronic acid) (NIBA) in aqueous solutions were studied rheologically at pH approximate to 9. The functional catechol group of NIDO and the boronic acid group of NIBA could form coordinative complexes, which are strong, yet could be broken by high deformation, while they could reconfigure quickly within 1 min on a macroscopic scale. The linear and nonlinear behaviors of these materials vary significantly for different component mixing ratios. At a total polymer concentration of 10 w/v %, the 1:1 mixture (w(NIBA)/w(NIDO)) of the two polymers yields the strongest gel compared with asymmetric blends. The nonlinearity intensities (I-n/I-1) of the materials increase proportionately with strain gamma(0), but once a significant nonlinearity is reached, they show lower nonlinearity intensities, which is unlike regular nonassociative single phase polymer melts and solutions. Interaction of polymer NIDO and NIBA and the formed supramolecular gels' properties will be clarified by large amplitude oscillatory shear characterization. (C) 2019 The Society of Rheology.