ABSTRACT Novel pH‐ and temperature‐responsive semi‐interpenetrating network (s‐IPN) microspheres were developed via a three‐step approach, involving radiation grafting of sodium alginate (SA) onto a poly(N‐isopropylacrylamide) (PNIPAAm) /poly(itaconic acid) (PIA) microsphere matrix. In the first step, PNIPAAm microspheres were prepared using the inverse suspension polymerization technique. In the second step, a selected fraction of PNIPAAm microspheres (180–250 µm size range) was used to prepare PNIPAAm/PIA graft copolymers via the radiation‐induced modification technique. Subsequently, PNIPAAm/PIA microspheres were immersed in an SA solution, followed by gamma radiation‐induced polymerization at a dose of 25 kGy. The prepared s‐IPN microspheres were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analyses. The swelling kinetics of the novel s‐IPN microspheres were best described by the Peppas model. The n > 0.5 value in the Peppas model indicates that the mechanism is non‐Fickian transport. The swelling behavior, pH‐sensitivity, swelling kinetics, and hydrolytic degradation properties of the new s‐IPN microspheres were improved by the incorporation of SA and itaconic acid (IA) into the gel structure.
Taşdelen et al. (Sun,) studied this question.
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