Copolymer hydrogel microspheres consisting of modified sulfate chondroitin‐co‐poly(N‐isopropylacrylamide)

Modified chondroitin sulfate (pi-CdS) microspheres were synthesized by way of crosslinking-copolymerization reaction with N-isopropylacrylamide (NIPAAm), yielding CdS-co-PNIPAAm copolymer network. The incorporation of vinyl groups onto the CdS was processed with the use of glycidyl methacrylate (GMA) in an aqueous solution of pH 3.5 under stirring speed of 800 rpm at 50 degrees C. C-13 NMR and H-1 NMR spectra of CdS treated with the GMA indicated the formation of 3-methacryloyl-1-glyceryl ester of pi-CdS and 3-methacryloyl-2-glyceryl ester of pi-CdS that are the reaction products resultant of an epoxide ring-opening mechanism via. The synthesis of microspheres was performed via radical reaction of the vinyl groups at the pi-CdS with vinyl groups at the NIPAAm in a water-benzyl alcohol microemulsion. The formation of spherical structures is the result of the polymerization-crosslinking reaction of the pi-CdS with the NIPAAm monomers at the droplets of water, in view that both reactants have hydrophilic characteristics at the temperature at which the reaction was processed. The pure CdS hydrogel microspheres showed a slightly cracked structure with a lower diameter range while the CdS-co-PNIPAAm hydrogel microspheres showed a flat and tight structure with a more regular mass distribution. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 2726-2733, 2011