Modular approach to synthesis of property tunable biodegradable polyesters derived from poly( ϵ -caprolactone)

Abstract

Surface erosion is desired in degradable polymers especially for drug delivery applications. The authors recently described a ground-up design strategy for the synthesis of surface eroding poly(α-hydroxy acids) through judicious introduction of lipophilicity. In the present study, the authors describe the synthesis and characterisation of poly(ϵ-caprolactone) (PCL) with tunable thermal properties. In the first step macromerdiols of differing hydrophobicities were assembled by initiating the ring opening polymerisation of ϵ-caprolactone monomer to varying degrees of polymerisation using alkanediol initiators of varying chemical make-up. These macromerdiols were then assembled into higher molecular weight polymers (M _w 30 000 to 120 000 g mol⁻¹, polydispersity index ranging from 2 to 5) through covalent linking using diacid chlorides of different carbon chain length, thereby impacting the physico–chemical characteristics of the polymers in two distinct well defined steps. These polyesters exhibited different solubility, glass transition temperature (T _g) and melting temperature (T _m) from pure PCL. Based on the authors’ past work these nanoengineered PCLs may be expected to undergo surface erosion.