Poly(acrylamide-co-acrylic acid)/chitosan semi-interpenetrating hydrogel for pressure sensor and controlled drug release

With high biocompatibility and pH-sensitivity, hybrid hydrogels of chitosan (CS) have been widely used in sensor, drug release systems, adsorption, agriculture, and other fields. Herein, a poly(acrylamide-co-acrylic acid)/chitosan [P(AM-co-AA)/CS] hydrogel with semi-interpenetrating (semi-IPN) network was synthesized through in situ copolymerization of acrylamide (AM), N,N '-methylene-bisacrylamide (MBAA) and acrylic acid (AA) solution of chitosan using potassium persulfate (KPS) and sodium bisulfite (SBS) as oxidation-reduction co-initiators. CS-AA complex monomer was prepared by dissolving CS in AA solution. Meanwhile, MBAA was used as a crosslinker to enhance the strength of the resulted hybrid hydrogels via introducing chemical crosslinking to the substrate P(AM-co-AA) copolymer. The morphology of the freeze-dried sample of P(AM-co-AA)/CS hydrogel shows dense interconnected pores. When the CS content is 2.4%, the P(AM-co-AA)/CS hydrogel has a compressive stress of 5.06 MPa at strain of 90.0% and a tensile strength of 161.71 kPa at strain of 1082.0%. The CP(AM-co-AA)/CS hydrogel also demonstrates extraordinary antifatigue property under cyclic compression of 85%. Because of the outstanding mechanical properties, a capacitive pressure sensor using P(AM-co-AA)/CS hydrogel as a dielectric with good durability and linearity at low operating voltage was fabricated. Besides, the water uptake of the P(AM-co-AA)/CS hydrogels is pH-sensitive, and the hydrogels could serve as a matrix for loading of ranitidine hydrochloride with controlled release under different pH environments.

Automated summary

A new semi-interpenetrating network hydrogel P(AM-co-AA)/CS with excellent mechanical properties and anti-fatigue characteristics was synthesized, which can be used to manufacture pressure sensors and drug-controlled release carriers.