Biporous polycaprolactone-like networks from 2-methylene-1,3-dioxepane: A versatile platform towards functional and reactive polyesters

Abstract

In this study, we report on the preparation of doubly porous “polycaprolactone-like” networks using a unique combination of 2-methylene-1,3-dioxepane, divinyl adipate, and either 2-chloroethyl vinyl ether or azidoethyl vinyl ether, allowing for the generation of functionalizable polyesters. Such reactive networks were synthesized via a free-radical ring-opening polymerization mechanism, employing a double porogen templating approach to generate a bimodal porosity. This resulted in macropores of around 200 μm generated after removal of a sieved and sintered NaCl template and smaller pores between 1 and 10 μm obtained through a phase separation process during the free-radical copolymerization of comonomers in the presence of a porogenic solvent. The incorporation of functional monomeric units into the copolymer backbone was evidenced by ATR-FTIR, while the concentration of reactive groups was controlled by finely adjusting the proportion of functional monomers in the copolymerization feed, as verified by EDX spectroscopy and elemental analysis. To demonstrate the versatility and potential applications of these functional degradable networks, a series of post-polymerization modifications was conducted. On the one hand, the pore surface associated with networks containing chloro pending groups was modified through nucleophilic substitution with different amino-compounds. On the other hand, for networks displaying azido groups at the pore surface, the Huisgen copper-catalyzed azide-alkyne cycloaddition modification was implemented for grafting a model fluorescent alkyne-modified compound. A comprehensive set of characterization techniques confirmed the successful completion of these post-polymerization modifications. These functionalized materials offer promising possibilities for applications in diverse fields, thanks to their tunable structure and physico-chemical properties, such as in biomedicine and notably for tissue engineering.