Structurally Controlled Dynamics in Azobenzene-Based Supramolecular Self-Assemblies in Solid State

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• 作者：Mikko Poutanen ; Olli Ikkala ; Arri Priimagi
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：June 14, 2016
• 年：2016
• 卷：49
• 期：11
• 页码：4095-4101
• 全文大小：436K
• 年卷期：0
• ISSN：1520-5835

文摘

Light-responsive supramolecular self-assemblies exhibit interplay between order and dynamics of the self-assembling motifs, through which the thermal isomerization rate of azobenzene chromophores can be tuned by orders of magnitude. By using supramolecular complexes of 4-(4-alkylphenylazo)phenols hydrogen-bonded to poly(4-vinylpyridine) as model systems, we demonstrate that the thermal isomerization rate of the hydroxyazobenzene derivatives increases 5700-fold when the material undergoes a transformation from a disordered, low-azobenzene-concentration state to a high-concentration state exhibiting lamellar, smectic-like self-assembly. Drastically smaller thermal isomerization rates are observed in disordered structures. This allows us to attribute the change to a combination of increased number density of the hydroxyazobenzenes inducing plasticization, and cooperativity created by the chromophore–chromophore interactions through self-assembled molecular order and alignment. Our results pinpoint the importance of molecular self-assembly and intermolecular interactions in modifying the dynamics in supramolecular complexes in a controlled manner. We foresee this to be important in light-controlled dynamic materials.