Preparation of Polyester Microspheres by Passerini Three-Component Dispersion Polymerization in Water

Abstract

Aqueous dispersion polymerization, predominantly based on the mechanism of radical polymerization, presents inherent limitations for polyester preparation through polycondensation or ring-opening polymerization approaches due to the substantial presence of water molecules. Herein, we report a facile and versatile strategy for the preparation of polyester microspheres (PEMs) via Passerini three-component dispersion polymerization (P-3CDP) under ambient aqueous conditions. By optimizing the polymerization parameters, we successfully synthesized a library of PEMs featuring diverse main-chain structures, including aliphatic carbon chains and functional backbones incorporating phenyl, alkenyl, biobased isosorbide, and furfuryl moieties, as well as reduction-responsive disulfide and pH-responsive Boc-protected l-glutamic acid groups. Comprehensive characterization of the resulting PEMs, including their chemical structures, microsphere morphologies, molar masses, and thermal properties, was performed using ¹H NMR, SEM, DLS, SEC, and DSC measurements. CCK-8 assays with mBMSC cells were conducted to assess the cytotoxicity and verify biological safety. Taking the PEM containing a Boc-protected l-glutamic acid backbone as an example, its pH-responsive self-immolative property was verified, suggesting the feasibility of straightforward preparation of stimuli-responsive PEMs through the aqueous P-3CDP method.