A Photochromic Copolymer Hydrogel Contact Lens: From Synthesis to Application

International Journal of Polymer Science, Oct 2016

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.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

http://downloads.hindawi.com/journals/ijps/2016/4374060.pdf

A Photochromic Copolymer Hydrogel Contact Lens: From Synthesis to Application

A Photochromic Copolymer Hydrogel Contact Lens: From Synthesis to Application Xiaoli Yang, Limin Huang, Lihua Zhou, Hao Xu, and Zihan Yi 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. Abstract 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. 1. Introduction Photochromic materials can change their color after being triggered by certain light due to a reversible structural transformation of chemical [1–3]. Spironaphthoxazine (SPO) based materials have attracted increasing interest due to their remarkable photochromic properties, such as excellent photostability, compatibility in various matrices, and high fatigue resistance [4–7]. These advantages enhance the practical applicability of SPO in optical systems for registration and storage [8], molecular switches [9], and UV sensors [10]. The photoresponsive site of the SPO comes from the center sp3 spiro carbon. Upon UV irradiation, the carbon-oxygen bond cleaves and achieves sp2 hybridization, yielding an open planar merocyanine (MC), which is metastable and readily isomerizes [11, 12]. So it can revert back to the spiro form via ring closing when irradiated with visible light or thermal radiation. We have previously synthesized a series of SPO derivatives and investigated their photochromic behaviors and thermal stability in different films [13]. All the compounds exhibited excellent photochromic properties upon UV irradiation. And their relaxation time was in a broad range (from 129 to 1724 s). On account of these merits, SPO was introduced into hydrogel contact lens in this work, aiming at endow contact lens with photochromic properties. As far as contact lens was concerned, hydrogel is a leading material of contact lens due to its good transparency, which satisfied the optic requirement of contact lens [14]. Moreover, hydrogel had a water swollen structure, which can mimetic nature biological environment. Thus, generally, hydrogel possesses good biocompatibility [15, 16]. Traditional hydrogel contact lens is polymerized by 2-hydroxyl-ethyl methacrylate (HEMA), but a number of problems restricted its application like low oxygen permeability, limited hydrophilicity, and poor antibacterial properties. Recently, some measures had been taken to improve these problems including copolymerizing with hydrophilic monomer [17], introducing chitosan to hydrogel network [18], and modifying surface via layer-by-layer assembly [19–21]. Further, in order to realize certain functions like drug delivery function, other functional monomers such as cyclodextrin (CD) had been introduced into contact lens by copolymerization [22, 23], by surface functionalization [24], or by nanocomposite technology [25]. Although the abovementioned researches had made considerable progress, they did not refer to photochromic contact lens. In this work, we attempted to introduce SPO into hydrogel contact lens by polymerization, investigate their properties, and explore their application. In order to improve the hydrophilicity, vinylpyrrolidone (NVP) has also been added. As a control, SPO blended hydrogel contact lens was also prepared. 2. Experimental2.1. Materials Hydroxyethyl methacrylate (HEMA) and N-vinylpyrrolidone (NVP) were obtained from Shanghai Jingchun Industries Co. Ltd., China, and distilled under vacuum before use. 2,2-Azobis(isobutyronitrile) (AIBN) was recrystallized from methanol. All other chemicals were analytically pure and were employed without any further drying or purification. Phosphate buffered saline (PBS) (pH 7.2) solution is as follows: 137 mmol L−1 NaCl (...truncated)


This is a preview of a remote PDF: http://downloads.hindawi.com/journals/ijps/2016/4374060.pdf

Xiaoli Yang, Limin Huang, Lihua Zhou, Hao Xu, Zihan Yi. A Photochromic Copolymer Hydrogel Contact Lens: From Synthesis to Application, International Journal of Polymer Science, 2016, 2016, DOI: 10.1155/2016/4374060