Fast-responsive temperature-sensitive hydrogels

Abstract

Temperature fast-responsive and magnetic poly(N-isopropylacrylamide-co-acrylamide) (CMX-MNP-PNIPAm/Fe3O4) hydrogels were developed using carboxymethyl xylan (CMX) as a pore-forming agent and a NaCl solution as the reaction medium, followed by fabricating Fe3O4 nanoparticles in situ within the hydrogel matrix. It was found that NaCl played a role in the phase separation and was used as the electrolyte to shield CMX molecular chains. The obtained hydrogels exhibited a fast, temperature-responsive behavior, and the water retention was less than 15% for 1 min under 60 °C. The prepared hydrogels showed enhanced mechanical properties and magnetic properties due to the presence of Fe3O4 particles. The lower critical solution temperature of the hydrogels was in the range of 35 to 39 °C, which was acquired through adjusting the amount of hydrophilic monomer (AM). The magnetic and thermosensitive hydrogel had the attractive photothermal conversion ability and could be heated to 40 °C within 2 min, and to 69 °C within 7 min under near infrared irradiation.