Synthesis of poly(3-keto-d-glucal) via conjugate addition polymerization†

Abstract

The widespread environmental impact of petrochemical-derived plastics has spurred interest in renewable alternatives. Herein, we report the design, synthesis, and polymerization of a novel sugar-derived monomer, dimethyl acetal-3-keto-D-glucal, using conjugate addition polymerization (CAP) to yield poly(3-keto-D-glucal) after post-polymerization deprotection. The monomer, synthesized in two steps from D-glucal, features an α,β-unsaturated enone motif compatible with CAP. Systematic optimization of reaction parameters—including solvent, catalyst, temperature, concentration, and time—revealed that acetonitrile as the solvent and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the catalyst yielded polymers with molecular weights up to 1080 kDa and dispersities as low as 1.54. Post-polymerization deprotection under mild conditions afforded hydroxyl-functionalized polymers with enhanced thermal stability and water solubility. The glass transition temperatures were determined to be 41 °C and 60 °C for the hydrophobic and hydrophilic polymers, respectively. These findings establish glycals as promising renewable monomers and highlight conjugate addition polymerization as a versatile method for synthesizing high-performance sugar-based polymers, contributing to the growing field of sustainable materials.