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International Journal of Polymer Science
Volume 2016, Article ID 4374060, 8 pages
Research Article

A Photochromic Copolymer Hydrogel Contact Lens: From Synthesis to Application

School of Material Engineering, Jinling Institute of Technology, Nanjing 211169, China

Received 27 June 2016; Revised 8 September 2016; Accepted 22 September 2016

Academic Editor: Xiao Gong

Copyright © 2016 Xiaoli Yang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A photochromic poly(2-hydroxyl-ethyl methacrylate-N-vinylpyrrolidone-spironaphthoxazine) hydrogel (p(HEMA-NVP-SPO)) has been designed and synthesized by free radical polymerization in this work. The chemical and structural information of hydrogels was investigated by IR spectra, equilibrium water content (EWC), and SEM. The IR spectra confirmed successful synthesis of copolymer. The domain of NVP contributed to not only EWC but also inner structure of hydrogel, while SPO had little influence on these properties of hydrogel. The photochromic behaviors of hydrogel including photochromic properties and thermal fading kinetics were systematically studied and compared with hydrogel made by immersing method. Results showed that when SPO was incorporated in hydrogel by polymerization, maximum absorbance wavelength got shorter, and the relaxation half-life became longer. In addition, salicylic acid as a drug model could be loaded into hydrogel by immersing method, and its sustained drug release in a given period was dependent on the characteristics of solution and loading time.