| 초록 |
In order to obtain a photo-responsive hydrogel, poly(vinyl alcohol) (PVA) having epoxypropoxy coumarin (EPC) as a pending group was cross-linked by photo-dimerization of the EPC pendants. EPC was covalently attached to PVA with the EPC/PVA molar ratio of 200/1 in reaction mixture. According to the 1H NMR spectrum of PVA-EPC and the colorimetic quantification of the EPC pendants, the molar ratio of EPC residue to PVC was about 5:1, indicating that EPC was attached to PVA every 407 repeating units of vinyl alcohol. An aqueous solution of PVA-EPC (5%) became a semi-solid hydrogel by the irradiation of a light (λ= 365 nm, 400 W) for 1 hr. The dimerization degree of EPC residues of the hydrogel can be controlled by alternatively UV light irradiation (λ= 365 nm and λ= 254 nm). The release rate of dye from the hydrogel increased upon irradiation of the sample with UV light (λ= 254 nm). |
