Gel-like ionic complexes for antimicrobial, hemostatic and adhesive properties†
Ion-specific effects offer a great opportunity to construct intelligent macromolecular systems with diverse architectures, on-demand controlled release behaviors and interfacial responsiveness. Herein, we developed gel-like polyelectrolyte/counterion complexes by ionotropic gelation of poly((trimethylamino)ethyl methacrylate chloride-co-sulfobetaine methacrylate) (poly(TMAEMA-co-SBMA)) and kosmotropic polyphosphate (PP). The strong water-mediated ionic crosslinking between the cationic poly(TMAEMA) and multivalent anionic PP leads to ionic association and formation of stable dispersive colloids and gel-like complexes. Zwitterionic SBMA possesses charge balance and strong hydration as well as insusceptibility to the presence of PP. The unique features of SBMA were applied to finely adjust the physical and biological properties of gel-like complexes. Accordingly, the molar composition of poly(TMAEMA-co-SBMA) was varied to evaluate its effects on the formation of the ionic complexes, water content, gel volume, ion-exchange capability, and viscoelastic recovery upon intermittent shear stress. The state diagrams of the poly(TMAEMA-co-SBMA) solutions as a function of the PP concentration were scrutinized in order to discover the relation between the ionic association and complex formation. The stability of the polymeric ionic complex structures was determined by the cationic molecular composition in the polymers and ionic strength. In terms of applications, the poly(TMAEMA-co-SBMA)/PP gel-like complexes served as an antimicrobial agent to inactivate pathogenic bacteria via leaching and contact killing approaches. The hemostasis of the complex gels in a tail-bleeding assay using Wistar rats was verified to ensure the potential in medical applications. Moreover, the gel-like complex was applied onto various substrates as an adhesive in comparison with commercial superglue gel, revealing the robust, substrate-independent, water-based, repeatable and removable adhesive property of the ionic complex glue. Consequently, this study was carried out in an attempt to explore the structure–property relation of ionically crosslinked polymer networks for a wide spectrum of applications.