Polynaphthalenes prepared by solid-state oxidative coupling polymerization and their microspheres self-assembled via nonsolvent vapor method

[Display omitted] •PNs were synthesized by solid-state oxidative polymerization in high yield.•The insoluble PNs have high char yield.•The soluble PNs can self-assemble to microspheres with nanosheets in MeOH vapor. Polynaphthalenes have successfully been synthesized by solid-state oxidative polymerization of naphthalene with FeCl3 as oxidant for 30min with a total polymerization yield of 98% at 25°C. On the basis of FT-IR, 1H NMR, elemental analysis and extended Hückel charge calculation results, the intermolecular 1,4-linked coupling is the main way to extend the polynaphthalene chain, accompanied with the formation of intramolecular coupling. The UV–Vis spectral band at 517nm also confirmed the formation of large π-conjugated structure. The chloroform-insoluble part of the polynaphthalenes with a high char yield of 85% after heated up to 600°C in nitrogen. In MeOH vapor atmosphere, the chloroform-soluble part of the polynaphthalenes can self-assemble to form microspheres patterns (average diameter 0.76μm) by the nonsolvent vapor method. The microspheres with nanosheets were obtained due to the semicrystalline structure of the polynaphthalenes.