A novel drug loading and release from a thermoresponsive hydrogel formed in situ emulsion polymerization

Abstract

ABSTRACTA facile thermoresponsive injectable hydrogel is prepared from stearyl methacrylate (SMA) and N‐isopropyl acrylamide (NIPAM) copolymers via reversible addition‐fragmentation chain‐transfer (RAFT) emulsion polymerization method. By regulating the content of the oil phase, emulsions with divergent properties are obtained. The yield stress and the viscosity results of the emulsions increase evidently as the initial content of the oil phase increase from 10 to 40%. The microstructures of 10% oil content sample (SN10) is seen as a dispersed particle whereas 20, 30, and 40% oil content samples (SN20, SN30, and SN40) appear as aggregated particles in a dilute solution that shows the microscopical phase transitions of the emulsions. Increasing the temperature from 15 to 45 °C, phase separation takes place, the emulsions contract to squeeze the water. A sharp decrease in particle size is noticed when the temperature increase from 30 to 35 °C. In this point, hydrophilic drug procaine is loaded and release experiments are conducted using thermoresponsive injectable hydrogel. The drug loading and release results are evaluated using the Weibull distribution model and the Fick's law of diffusion that precisely works out. A thermoresponsive injectable hydrogel offers an efficient, cost‐effective, and scalable approach towards controlled release of drugs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48669.