Impact of the molecular structure of cationic binders on the rheological and adhesive properties of carboxymethyl cellulose-based coacervate hydrogels

In this work, we investigate the impact of organic oligo(cationic) binders on the rheological and adhesive properties of carboxymethyl cellulose. The behaviour of gels in the presence of organic oligo(cations) (ethylene imine-based), including block copolymers of poly(ethylene imine) and poly(ethyene glycol), is studied via oscillatory rheology and shear lap testing and compared to that of inorganic cations. We find that more polarisable inorganic cations (Sr 2+ ) and organic oligo(cations) display weaker rheological properties (storage shear moduli), as a result of the increased conformational collapse associated with corresponding complexes, compared to harder inorganic cations (Ca 2+ ). However, Sr 2+ and block copolymers of oligo(ethylene imine)-based complex gels display increased adhesive strength, as a result of increased dissipative mechanisms.