Poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene/permethylated β-cyclodextrin) main-chain polyrotaxane: Synthesis, characterization and surface morphology

• Conjugated polyrotaxane having lipophilic βCD as host molecules has been reported.
• The inclusion complex formation was proved by MM+, PM3 calculation and mass spectra.
• The rotaxane formation leads to distinct improvements of the physical properties.

Poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene/permethylated β-cyclodextrin) (3·PMeβCD) main-chain polyrotaxane was synthesized according to a Suzuki-type aryl-aryl coupling protocol, by reacting 9,9-dioctylfluorene-2,7-trimethylene diborate (1) with an inclusion complex of 5,5′-dibromo-2,2′-bithiophene (2)/permethylated-βCD (PMeβCD) (2·PMeβCD). The complexation ability of PMeβCD molecule towards monomer 2 was confirmed by MM+ and PM3 quantum-mechanics semi-empirical methods, ESI-MS, (ESI) MS/MS analysis, as well as FTIR and 1H-NMR spectroscopy. A conjugated polyrotaxane copolymer with PMeβCD/structural unit ratio of about 1/3 and the number average molecular weight (Mn) value of 30600 was obtained by 1H-NMR spectroscopy and gel permeation chromatography, respectively. The thermal, optical, surface morphology and the adhesion characteristics were investigated and compared to those of the non-rotaxane counterpart poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene) (3).

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