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Keywords:

  • conjugated polymers;
  • mechano-responsive;
  • smart materials;
  • spiropyran;
  • sonochemistry

Abstract

The first main-chain conjugated copolymers based on alternating spiropyran (SP) and 9,9-dioctylfluorene (F8) units synthesized via Suzuki polycondensation (SPC) are presented. The reaction conditions of SPC are optimized to obtain materials of type P(para-SP-F8) with appreciably high molecular weights up to Mw ≈ 100 kg mol−1. 13C NMR is used to identify the random orientation of the non-symmetric SP unit in P(p-SP-F8). Ultrasound-induced isomerization of P(p-SP-F8) to the corresponding merocyanine form P(p-MC-F8) yields a deep-red solution. This isomerization reaction is followed by 1H NMR in solution using sonication, whereby the color increasingly changes to deep red. The possibility to incorporate multiple SP units into main-chain polymers significantly broadens existing SP-based polymeric architectures.