Ring-opening polymerization driven by aromatization energy

Abstract

To investigate the polymerization systems driven by aromatization energy, 10-methylene-9,10-dihydroanthryl-9-spirocyclopropane (MASC), 10-methylene-9,10-dihydroanthryl-9-spirophenylcyclopropane (MASPC), 8-methylene-1,4-dioxaspiro [4,5] deca-6,9-diene (MDOSD), 8-methylene-1-oxaspiro [4,5] deca-6,9-diene (MOSD) were prepared, and their polymerization behaviors under various conditions and the properties of the resulting polymers were investigated. Polymerizations of MASC and MASPC were carried out with common radical initiators such as 2,2$^\prime$-azobisisobutyronitrile, dibenzoyl peroxide. MASPC polymerized well and cleanly in ring-opening fashion accompanied by aromatization. MASC also polymerized well but its polymers were not soluble in solvents probably because of its high crystallinity. All the spectra data indicated that the radical polymerization of MASC and MASPC proceeded with aromatization and ring-opening. Aromatization energy was strong enough driving force to promote 100\% ring-opening to insert p-anthrylene groups into the backbone of the resulting polymer. The polymers of MASC and MASPC decomposed above 370$^\circ$C as determined by TGA. The electrical conductivity of the polymer even in the doped state failed to show high conductivity (10$^{-7}$10$^{-8}$S/cm, but deserves further work. MDOSD polymerized well with various cationic initiators and cleanly in ring-opening accompanied by aromatization. This behavior was confirmed by model study employing $^1H$-NMR, $^{13}C$-NMR, IR spectra of monomers and polymers. The polymer of MDOSD had a glass transition at 15$^\circ$C detected by DSC and decomposed above 456$^\circ$Cas shown on TGA. Radical polymerization of MDOSD with AIBN took place in high conversion and the main structure was similar to that of cationic polymerization except the rise of small side peaks in the NMR spectra. This system is a rare instance in that alkoxy radical generated by ring-opening driven by aromatization energy was propa...