Tandem ATRP/Diels–Alder synthesis of polyHEMA-based hydrogels

The efficient, controlled polymerization of a batch of new poly(hydroxyethyl methacrylate-co-furfuryl methacrylate)s, [poly(HEMA-co-FMA)], of various compositions was achieved using atom transfer radical polymerization (ATRP) in methanol. When the FMA composition did not exceed the 10 mol% ratio, the evolution of molecular weight with conversion was linear, and polydispersities were around 1.1 for polymerization reactions at 15 °C and around 1.3–1.4 at 25 °C, indicating good control over the polymerization process. HEMA-based hydrogels were obtained by means of the Diels–Alder reaction between poly(HEMA-co-FMA) and an hydrophilic bisdienophile. Gelification was monitored by diffusion-filtered ¹H NMR and solution ¹H NMR spectroscopy. Modulated temperature differential scanning calorimetry (MTDSC) suggests the thermo-reversibility of the Diels–Alder coupling reaction of HEMA polymeric networks. Rheological studies showed that the linear viscoelasticity functions of hydrogels were influenced by the chemical composition.