Photo-Induced Order-Disorder Transitions in Block Copolymer Solutions

ORAL

Abstract

Photo-stimuli responsive materials are of interest for a broad range of applications, and take advantage of the inherently non-invasive, spatially resolved, and species-selective optical response. We demonstrate here a photo-reversible order-disorder transition in a block copolymer/ionic liquid system. The copolymer is a symmetric poly(methyl methacrylate)-b-poly(benzyl methacrylate-stat-azomethacrylate) diblock, with M ≈ 45 kDa, and 5% azomethacrylate in the second block. Poly(benzyl methacrylate) exhibits LCST behavior in the common ionic liquid ethyl methyl imidazolium bistrifluoromethylsulfonimide (EMI TFSI). Under UV irradiation, the trans to cis photoisomerization of azobenzene significantly increases the solubility of the thermoresponsive block, leading to an order-to-disorder transition at appropriate concentrations and temperatures. Under visible light, the cis to trans recovery causes the sample to re-order. The progress of the transition is monitored by in situ photo-rheology, and the morphologies are confirmed by SAXS.

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Presenters

  • Timothy Lodge

    University of Minnesota, Department of Chemistry, University of Minnesota, Twin Cities, University of Minnesota - Twin Cities, Chemistry, University of Minnesota, Department of Chemistry, University of Minnesota

Authors

  • Timothy Lodge

    University of Minnesota, Department of Chemistry, University of Minnesota, Twin Cities, University of Minnesota - Twin Cities, Chemistry, University of Minnesota, Department of Chemistry, University of Minnesota

  • Cecilia C Hall

    University of Minnesota

  • Cecelia Rivera

    University of Minnesota

  • Claire Seitzinger

    University of Minnesota

  • Yuki Hirose

    University of Minnesota