Photochromic copolymers containing 3-indolylfulgides/indolylfulgimides: Synthesis and photochemical properties in toluene and as films

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• 作者：Nadezhda I. Islamova ; Xi Chen ; Chang-Jun Fan ; Richard S. Andino ; Watson J. Lees
• 关键词：Photochromism ; 3-Indolylfulgimide ; Cross-linked copolymer ; Thin films
• 刊名：Polymer Degradation and Stability
• 出版年：2013
• 出版时间：September, 2013
• 年：2013
• 卷：98
• 期：9
• 页码：1662-1670
• 全文大小：1718 K

文摘

Photochromic indolylfulgimides covalently attached to polymers have beneficial properties for optical switching. A 3-indolylfulgide and two 3-indolylfulgimides with one or two polymerizable styrene groups attached on the nitrogen atom(s) were synthesized. Copolymerization with methyl methacrylate (MMA) provided linear copolymers (one styrene group) or a cross-linked copolymer (two styrene groups). The properties of the monomers and copolymers in toluene or as thin films were characterized. The new copolymers were photochromic (reversible Z-to-C isomerization), absorbed visible light, and revealed good thermal and photochemical stability. At room temperature, all copolymer films showed no loss of absorbance after 5 weeks. At 80?¡ãC in either toluene or as films, the Z-forms copolymers were less stable than the C-form copolymers, which showed little or no degradation after 400?h. The degradation rate due to repeated ring-closing - ring opening cycles was less than 3 % per 100 cycles. The cross-linked copolymer showed photochemical stability comparable to monomeric fulgides in toluene, <1 % per 100 cycles. In general, the properties of the linear and cross-linked copolymers were similar to the corresponding monomers in toluene. In films, the conformations of the Z-form were restricted due to the matrix indicating that the preparation of films from the C-form is advantageous.