Controlled Release of Vitamin B-12 Using Hydrogels Synthesized by Free Radical and RAFT Copolymerization in scCO2

Summary Research in polymer network synthesis is mostly focused on materials with absorbent or controlled‐release properties. They are important in healthcare applications. Free radical copolymerization is the main route to obtain gels, using monomers and crosslinking agents, but the materials produced by this route are highly heterogeneous. These heterogeneities reduce the efficiency of chemical compounds used in controlled‐release applications. Our research is focused on creating new routes of polymer synthesis to reduce these heterogeneities. In this article, we compare gels synthesized by conventional free radical and by reversible addition‐fragmentation chain transfer (RAFT) copolymerization of acrylic monomers in supercritical carbon dioxide. These gels are evaluated for controlled drug delivery applications with vitamin B12. The materials were characterized by scanning electron microscopy (SEM), nitrogen adsorption (BET), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). These characterization techniques allowed us to determine the morphology and texture of each hydrogel and to explain how vitamin release performance is affected by these characteristics of the hydrogel.