Reversible Photoswitching in Poly(2-oxazoline) Nanoreactors

Michael Kuepfert, Peiyuan Qu, Aaron E. Cohen, Caroline B. Hoyt, Christopher W. Jones, Marcus Weck

Research output: Contribution to journalArticle

Abstract

This contribution reports light responsive catalytic nanoreactors based on poly(2-oxazoline) diblock copolymers. The hydrophobic block of the copolymer is a random copolymer consisting of a spiropyran functionalized 2-oxazoline (SPOx) and 2-(but-3-yn-1-yl)-4,5-dihydrooxazole (ButynOx), while the hydrophilic block is based on 2-methyl-2-oxazoline (MeOx). The block copolymer is terminated with tris(2-aminoethyl) amine (TREN) that serves as catalyst in a Knoevenagel condensation. Four block copolymers with different ButynOx/SPOx and hydrophilic/hydrophobic ratios are synthesized and self-assembled through solvent exchange. Micelles and vesicles of various sizes are observed by TEM, which undergo morphological and size changes in response to irradiation with UV light. We hypothesize that these transformations in the nanostructures are caused by increases in the hydrophilicity of the hydrophobic block when spiropyran (SP) isomerizes to merocyanine (MC) in the presence of UV light. The reversible transition from micellar to vesicular nanoreactors resulted in increased reaction kinetics through improved substrate accessibility to the catalytic site, or termination of the catalytic reaction due to polymer precipitation. These nanoreactors present a promising platform towards photoregulating reaction outcomes based on changes in nanostructure morphology.

Original languageEnglish (US)
Pages (from-to)11776-11781
Number of pages6
JournalChemistry - A European Journal
Volume26
Issue number51
DOIs
StatePublished - Sep 10 2020

Keywords

  • micelles
  • morphology change
  • nanoreactors
  • photoswitches
  • vesicles

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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  • Cite this

    Kuepfert, M., Qu, P., Cohen, A. E., Hoyt, C. B., Jones, C. W., & Weck, M. (2020). Reversible Photoswitching in Poly(2-oxazoline) Nanoreactors. Chemistry - A European Journal, 26(51), 11776-11781. https://doi.org/10.1002/chem.202000179