Controllable synthesis of a novel poly(vinyl alcohol)-based hydrogel containing lactate and PEG moieties

Tunable hydrogel that contained well-defined poly(vinyl alcohol) (PVA), labile lactate groups, and hydrophilic poly(ethylene glycol) (PEG) segments was prepared through a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and esterification reaction. A diol was prepared via the esterification between lactic acid (LA) and PEG. Then the diol was allowed to react with maleic anhydride to produce a diacid. Meanwhile, well-defined PVA was synthesized by the alcoholysis of poly(vinyl acetate) (PVAc) obtained by RAFT polymerization of vinyl acetate. The hydrogels with tailor-made structure were generated by crosslinking PVA with LA-based diacid. The structures and properties of LA-based intermediates and the hydrogels were characterized with Fourier transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Both LA-based diol and diacid were semicrystalline and water-soluble, their melting temperature and glass transition temperature were 52 and -51, 54 and -41°C, respectively. The polydispersity indexes of the precursor of PVA samples were within the range of 1.03-1.10. It was found that the thermal stability of hydrogel was higher than that of LA-based diacid. Both the swelling and release properties of the hydrogels depend on the feeding ratio of PVA/LEM and the chain length of PVA, which reflected that the structure and properties of the hydrogels were controllable.
INTRODUCTION Owing to the advantages such as nontoxic, biocompatible, excellent mechanical and physicochemical properties, biodegradable hydrogels are regarded as suitable materials for biomedical, pharmaceutical, environmental, and other applications [1-3]. The [...]