Influence of Supramolecular Interaction Type on Photoresponsive Azopolymer Complexes: A Surface Relief Grating Formation Study

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• 作者：Xin Wang ; Jaana Vapaavuori ; Xiaoxiao Wang ; Ribal Georges Sabat ; Christian Pellerin ; C. Geraldine Bazuin
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：July 12, 2016
• 年：2016
• 卷：49
• 期：13
• 页码：4923-4934
• 全文大小：517K
• 年卷期：0
• ISSN：1520-5835

文摘

The influence of the supramolecular interaction type—hydrogen bonding, proton transfer, and pure ionic bonding—on photoresponsive behavior, particularly surface relief grating (SRG) inscription, has been investigated using a homopolymer with an ambient temperature glass transition (T_g). To this end, poly(dimethylaminoethyl methacrylate) (PDMAEMA or PDM) of relatively high molecular weight (42K) was complexed at various azo/DM molar ratios with dimethylaminoazobenzene derivatives functionalized by hydroxyl (azoOH) or carboxylic acid (p-methyl red or azoCOOH) groups, and quaternized PDM (PDMQ) was complexed at equimolar ratio with a sulfonated analogue (methyl orange or azoSO₃), and the structural and thermal properties of these complexes were determined. SRG inscription on spin-coated films was found to be possible because complexation increases the T_g above ambient. The efficiency of SRG inscription on spin-coated films, which increases with azo content, is highest for the purely ionic azoSO₃/PDMQ complex despite its very high T_g, while the proton transfer azoCOOH/PDM complexes, involving ionic and H-bonding with acid-salt structures, show somewhat more efficient SRG inscription than do the purely hydrogen-bonded azoOH/PDM complexes, and this despite some azoCOOH crystallization at the highest molar ratios. These findings clarify the comparative effectiveness of different supramolecular bond types on SRG inscription and provide a useful guide for the design of supramolecular photoresponsive polymers for SRG applications.