The Rapid Chain Extension of Anthracene‐Functional Polyesters by the Diels‐Alder Reaction with Bismaleimides

Summary: The chain extension of anthracene end‐capped oligoesters by reaction with bismaleimides constitutes a rapid route to high molecular weight polyesters. Polytransesterification of bis(2‐hydroxyethyl) terephthalate in the presence of a small amount of 2‐hydroxyethyl 2‐anthracenecarboxylate provides low molecular weight anthracene‐terminated macromers with anthracene end group functionality (f_AN) of 1.66–1.85. These are subject to rapid chain extension with di(4‐maleimidophenyl)methane by Diels‐Alder cycloadditions resulting in consumption of the anthracene and maleimide end groups to generate polymers with $\overline M _{\rm n}$ > 2.0 × 10⁴ g · mol⁻¹. Thus, generation of the polymeric structure is achieved rapidly by addition reactions rather than sluggish transesterification reactions in which a condensate must be removed from the viscous polymer melt. Chain extension of low‐molecular weight 2‐anthracenecarboxylate terminated oligoesters. magnified image Chain extension of low‐molecular weight 2‐anthracenecarboxylate terminated oligoesters.