Super‐macroporous composite cryogels based on biodegradable dextran and temperature‐responsive poly(N‐isopropylacrylamide)

This contribution describes the fabrication of super‐macroporous cryogels comprising an interpenetrating network of biodegradable dextran and temperature‐responsive poly(N‐isopropylacrylamide) (PNIPAAm) segments. Cryogels were prepared from nonmodified dextran and N‐isopropylacrylamide (NIPAAm) via cryogenic treatment of their aqueous solutions and subsequent irradiation with Ultraviolet light. The weight ratio of the two precursors was varied in order to find out the proper conditions for producing cryogels of high gel fraction yield and favorable physico‐mechanical properties. Temperature‐responsive behavior and enhanced elastic modulus were established for cryogel materials containing ≥50 wt% PNIPAAm. Scanning electron microscopy study revealed an open‐porous structure of cryogels below and above the temperature of volume phase transition. Such morphology featured a very quick response of the material to temperature changes. The capability of dextran/PNIPAAm cryogels for instant release of water‐soluble substances was demonstrated as well. Super‐macroporous cryogels based on biodegradable dextran and temperature‐responsive poly(N‐isopropylacrylamide) (PNIPAAm) interpenetrating network were prepared via the combination of cryogenic treatment and photochemical crosslinking. The open‐porous structure and the temperature‐responsive network enabled an instant release of bioactive substances upon stimuli.