Photodynamic control of the chain length in supramolecular polymers: switching an intercalator into a chain capper

Elisabeth Weyandt, Gijs M. ter Huurne, Ghislaine Vantomme, Albert J. Markvoort, Anja R.A. Palmans, E.W. Meijer (Corresponding author)

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Supramolecular systems are intrinsically dynamic and sensitive to changes in molecular structure and external conditions. Because of these unique properties, strategies to control polymer length, composition, comonomer sequence, and morphology have to be developed for sufficient control over supramolecular copolymerizations. We designed photoresponsive, mono acyl hydrazone functionalized benzene-1,3,5-tricarboxamide (m-BTA) monomers that play a dual role in the coassembly with achiral alkyl BTAs (a-BTA). In the E isomer form, the chiral m-BTA monomers intercalate into stacks of a-BTA and dictate the chirality of the helices. Photoisomerization to the Z isomer transforms the intercalator into a chain capper, allowing dynamic shortening of chain length in the supramolecular aggregates. We combine optical spectroscopy and light-scattering experiments with theoretical modeling to show the reversible decrease in length when switching from the E to Z isomer of m-BTA in the copolymer with inert a-BTA. With a mass-balance thermodynamic model, we gain additional insights into the composition of copolymers and length distributions of the species over a broad range of concentrations and mixing ratios of a-BTA/m-BTA. Moreover, the model was used to predict the impact of an additive (chain capper and intercalator) on the chain length over a range of concentrations, showing a remarkable amplification of efficiency at high concentrations. By employing a stimuli-responsive comonomer in a mostly inert polymer, we can cooperatively amplify the effect of the switching and obtain photocontrol of polymer length. Moreover, this dynamic decrease in chain length causes a macroscopic gel-to-sol phase transformation of the copolymer gel, although 99.4% of the organogel is inert to the light stimulus.

Original languageEnglish
Pages (from-to)6295-6303
Number of pages9
JournalJournal of the American Chemical Society
Issue number13
Publication statusPublished - 1 Apr 2020


This project received funding from the Marie Sklodowska-Curie Grant Agreement No. 642083 of the European Union’s Horizon 2020 research and innovation program, The Netherlands Organization for Scientific Research (NWO-TOP PUNT Grant No. 10018944, NWO-Veni Grant 722.017.003), and the Dutch Ministry of Education, Culture and Science (Gravitation Program 024.001.035). The ICMS Animation Studio (Eindhoven University of Technology) provided the illustrations of molecules. Huub M. M ten Eikelder is thanked for fruitful discussions on the theoretical models. The authors also thank Marcin L. Ślȩczkowski for providing starting materials for the synthesis of the compounds. Mathijs Mabesoone, Fabian Eisenreich, and Lafayette de Windt are acknowledged for the helpful discussions.

FundersFunder number
NWO‐TOP PUNT10018944
Horizon 2020 Framework Programme
Marie Skłodowska‐Curie642083
Ministerie van Onderwijs, Cultuur en Wetenschap024.001.035
Nederlandse Organisatie voor Wetenschappelijk Onderzoek


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