Reprogrammable and Light-Adaptive Mechanical Gradients in Waterborne High-Performance Nanocellulose Materials

• Applicants: Professor Dr. Christopher Barner-Kowollik; Professor Dr. Andreas Walther
• Subject Area: Polymer Materials
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 289996893

• Final Report Year: 2020

Final Report Abstract

The current project has unambiguously shown that photochemical reactions and in particular reversible cycloadditions that are triggered with visible light hold vast promises towards light adaptive and reprogrammable materials. With its mild reaction wavelengths, styrylpyrene has proven highly suitable to be employed in reversible materials over several lifecycles. Styrylpyrene can also be combined with other chromophores to achieve wavelength-orthogonal materials that can be altered simply by the choice of the colour of light. Based on the research of this proposal we have been able to use styrylpyrene in manifold ways, e.g. for nanoparticles14 or triggered through chemiluminescence,15 while a wide range of other applications are still being explored. All research aimed at forming tetrazole/maleimide CNF materials has been very successful and we could show a versatile platform for photochemical functionalization of diverse nanocellulose materials – nanopaper surfaces, hydrogels and pattern bulk nanocomposites. Yet in the context of photochemically reprogrammable materials, there are drastic solubility problems when functionalizing the polymers or the CNF with the bulkier StyP-units. We could show successful photocrosslinking strategies for bioinspired nanopapers with non-functionalized CNFs for both linear, as well as starshaped polymers. However, proper films could not be prepared based on functionalized CNFs so far. In late stages of the project, we identified that cyclodextrin might be a key solubility enhancer for our materials and we are currently still investigating in follow up work, whether cyclodextrin can be used as additive to promote solubility, proper structure formation in bioinspired nanocomposites and hydrogels, and allows to include functionalized CNFs in the materials for achieving a propert interfacial adhesion, what would boost the mechanical performance drastically.

Publications

• Photochemical Ligation Meets Nanocellulose: A Versatile Platform for Self-Reporting Functional Materials. Mater. Horiz. 2018, 5, 560
  D. Hoenders, J. Guo, A. S. Goldmann, C. Barner-Kowollik, A. Walther
  
• Photochemistry in Confined Environments for Single-Chain Nanoparticle Design, J. Am. Chem. Soc. 2018, 140, 9551
  H. Frisch, J. P. Menzel, F. R. Bloesser, D. E. Marschner, K. Mundsinger, C. Barner-Kowollik
  
• Visible Light [2+2] Cycloadditions for Reversible Polymer Ligation, Macromolecules 2018, 51, 3802
  D. E. Marschner, H. Frisch, J. T. Offenloch, B. T. Tuten, C. R. Becer, A. Walther, A. S. Goldmann, P. Tzvetkova, C. Barner-Kowollik
  
• Wavelength‐Gated Dynamic Covalent Chemistry, Angew. Chem. Int. Ed. 2018, 57, 2036
  H. Frisch, D. E. Marschner, A. S. Goldmann, C. Barner-Kowollik
  
• Wellenlängengesteuerte dynamische kovalente Chemie, Angew. Chem. 2018, 130, 2054
  H. Frisch, D. E. Marschner, A. S. Goldmann, C. Barner-Kowollik
  
• Access to Disparate Soft Matter Materials by Curing with Two Colors of Light, Adv. Mater. 2019, 31, 1807288
  D. E. Marschner, S. Bialas, L. Michalek, T. Krappitz, M. Wegener, J. Blinco, E. Blasco, H. Frisch, C. Barner‐Kowollik
  
• Fully Independent Photochemical Reactivity in One Molecule, Chem. Commun. 2019, 55, 9877
  D. E. Marschner, C. O. Franck, D. Abt, H. Mutlu, C. Barner-Kowollik