Synthesis of Linear Polymers in High Molecular Weights via Reaction-Enhanced Reactivity of Intermediates Using Friedel-Crafts Polycondensation

Abstract

Linear polymers for many materials applications are popularly produced via step-growth polymerizations of different pairs of A₂ and B₂ monomers. However, achieving high molecular weights during the synthesis is dramatically limited by the required stoichiometric balance of A and B reactive groups when reactivity is considered unchanged during the polymerization. This short review summarizes the recent progress on using Friedel-Crafts polycondensation reactions to produce high-molecular-weight linear polymers via the reaction-enhanced reactivity of intermediate (RERI) mechanism, in which the reaction of one functional group in the bifunctional monomer spontaneously increases the reactivity of the other functional group on the monoreacted intermediate for faster consumption and connection into polymer chains. Thus, using an excess amount of this monomer produces linear polymers in high molecular weights. Both Friedel-Crafts acylation and hydroxyalkylation reactions have been reported for syntheses of long polymer chains under nonstoichiometric conditions, although the focus is to illustrate the significant progress of applying Friedel-Crafts hydroxyalkylation reactions to produce linear polymers with high molecular weights and varied compositions.