Effect of oxyfluorination of PVA/PNIPAAm hydrogel on temperature responsive drug release

The temperature-responsive poly(vinyl alcohol)/poly(N-isopropylacrylamide) hydrogel was prepared as a drug delivery carrier. The vitamin B12 release behavior of hydrogel was controlled by direct oxyfluorination. The oxyfluorination of hydrogel changed the surface characteristics to have hydrophilic functional groups. On the other hand, the hydrophobicity of hydrogel increased by fluorination treatment due to the induced hydrophobic functional groups. C-O bond and C-F bond were mainly formed by oxyfluorination and fluorination, respectively. The surface morphology showed the significant variation depending on the oxyfluorination conditions. Both swelling ratio and drug release rate were strongly dependent on the oxyfluorination conditions. The swelling of hydrogel increased further by the surface modification with oxyfluorination in a higher oxygen content to give more hydrophilic properties. The drug release from hydrogel also increased as more hydrophilic functional groups were introduced by oxyfluorination because the favorable affinity at the interface resulted in a higher swelling ratio. On the other hand, the relatively low swelling ratio and slower drug release from hydrogel were observed with more hydrophobic functional groups introduced by fluorination.