Synthesis of aromatic polyethers by the Scholl reaction. Part 9.—Cation–radical polymerization of 4,4′-bis(2-naphthoxy)diphenyl sulphone

Abstract

The synthesis and cation–radical polymerization of 4,4′-bis(2-naphthyloxy)diphenyl sulphone (3) are presented. For long reaction times, the soluble fractions of the polymers resulting from 3 exhibit a multi-modal molecular-weight distribution consisting of three peaks of very different molecular weights. The highest molecular-weight fraction usually has a number-average molecular weight (_n) of ca. 10⁶ g mol^–1 relative to a polystyrene calibration, while the _n of the lowest molecular-weight fraction is usually < 10 000 g mol^–1. The multimodal molecular-weight distribution of the polymers synthesized from 3 was suggested to be due to the participation in reactions of several reactive positions on the 2-naphthyloxy rings. The reaction between the most reactive C₁ positions takes place during the early stage of the polymerization. However, once the concentration of C₁ positions decreases at a number-average molecular weight of ca. 10 000 g mol^–1, intermolecular reactions between the less reactive positions such as C₅, C₈ and C₄ of the low-molecular-weight polymer chains causes the formation of a branched polymer fraction of very high molecular weight and also a small amount of an insoluble fraction. A polymer fraction of intermediary molecular weight is also obtained.