Synthesis and thermal and spectroscopic properties of macrocyclic vinyl aromatic polymers

Well-defined and narrow molecular weight distribution macrocyclic poly(2-vinylnaphthalene) (P2VN) and poly(2-vinyl-9,9-dimethylfluorene) (PDMVF) containing a single 1,4-benzylidene or 9,10-anthracenylidene unit have been synthesized via the potassium naphthalide initiated polymerization of the monomers followed by the end-to-end coupling of the resulting P2VN dianions under high-dilution conditions with 1,4-bis(bromomethyl)benzene or 9,10-bis(chloromethyl)anthracene. Molecular characterization has been carried out by size exclusion chromatography, nuclear magnetic resonance, differential scanning calorimetry, ultraviolet-visible spectroscopy, and matrix-assisted laser desorption/ionization time-of-fiight mass spectrometry. The thermal properties show distinct differences between the cyclic and matching linear polymers, with the macrocycles showing much higher glass-transition and decomposition temperatures. The absorption bands are both hyperchromic and hypochromic with respect to the model aromatic compounds, and this is consistent with intensity borrowing.