Catalyst Control of Polyester Branching in the Hydroesterificative Polymerization of 10-Undecen-1-ol

Unlike polyolefin synthesis, where catalysts can be used to control the microstructure and generate multiple different materials from a single monomer, polyester microstructures are typically dictated by the monomer feedstock structure. Here, catalyst control of the degree of branching in poly(dodeceyloate) via hydroesterificative polymerization of 10-undecen-1-ol is reported. By varying palladium precursors and monophosphine ligands, poly(dodecyloate) with alpha methyl branching percentages ranging from 28 to 78% can be achieved. These polyesters initially feature moderate molecular weights ranging from 7.2 to 9.4 kg/mol, but an additional transesterification step can increase the molecular weight up to 15.8 kg/mol, sidestepping challenges associated with low conversions in branch-selective hydroesterification reactions. The branched content can be further fine-tuned through a dual catalytic strategy, where the use of phosphine ligand mixtures can yield multiple active catalytic species (of varying regioselectivity) that can cooperatively construct the polyester through step-growth polymerization.