Effect of xylan sulfate on the responsive swelling behavior of poly(methacrylatoethyl trimethyl ammonium chloride)-based composite hydrogels

Xylan sulfate, one important xylan derivative, was prepared using microfluidic reactor system and incorporated in situ under the polymerization of methacroylcholine chloride (DMC), resulting in composite hydrogels containing variable amount of xylan sulfate. The introduction of xylan sulfate imparts enhanced temperature-swelling responsiveness to the hydrogels, and substantially increases their water swelling ratio up to > 200 g/g, which is twice higher than the neat polyDMC hydrogel. Such swelling behavior may relate to the electrostatic interaction between the –SO₃⁻ in xylan sulfate and the –NH₄⁺ in polyDMC. This interaction significantly improves the formation of porous architecture and the tensile toughness of the hydrogels. The composite hydrogels exhibit responsive swelling behavior at different salt, pH, and solvent conditions due to osmotic pressure decline, charge shielding and salting-out effect. They load 2.2 times amount of tetracycline hydrochloride and show 50.3% slower release rate than the neat polyDMC hydrogel, which shows great potential for drug delivery applications.