Different polymerization techniques of poly(N-vinyl caprolactam) (PNVCL) have been reported including the photo polymerization via ultraviolet (UV). However, photo polymerization of PNVCL via UV-C (wavelength of 254 nm) has not been reported. In this study, N-vinyl caprolactam was polymerized via UV-C irradiation at different time periods. Fouirer transform infrared spectroscopy (FTIR) analysis showed that the PNVCL has been successfully synthesized via the photo polymerization method. The optimum conversion time was found as about 70 min and the conversion was found as 71.2%. Gels displayed different swelling behavior at temperatures above and below lower critical solution temperature (LCST), and swelling analysis, dynamic light scattering (DLS) and differential scanning calorimetry (DSC) were performed to investigate the phase change behavior. It was observed that LCST of the synthesized gels occurs between 31 and 35 ^oC determined by DSC analysis, which is also consistent with DLS and swelling analysis results. In conclusion, a facile and short time period polymerization technique is reported via use of UV-C photo polymerization technique.

Keywords: poly(N-vinyl caprolactam), UV-C irradiation, polymerization, temperature responsive polymer, lower critical solution temperature