In situ photocrosslinkable nanohybrids based on poly(ε-caprolactone fumarate)/polyhedral oligomeric silsesquioxane: synthesis and characterization

Abstract

Two types of biodegradable, in situ photocrosslinkable macromers were synthesized consisting a linear copolyester i.e., PCLF based on fumaric acid (FA) and poly(e-caprolactone diol) (PCL diol), and its nanohybrid counterpart (POSS-PCLF) composed of FA, PCL diol and polyhedral oligomeric silsesquioxane (POSS). Chemical structure of the macromers was characterized by 1HNMR and FTIR spectroscopy. The synthesized macromers were photocrosslinked by visible light irradiation in the presence of camphorquinone and N,N’-dimethylaminoethyl methacrylate as a photoinitiator and accelerator, respectively. Photocrosslinking characteristics of the compositions were investigated as a function of the initial PCL diol molecular weight, presence of POSS nanoparticles or N-vinylpyrrolidone (NVP, as a reactive diluent) by tracing degree of conversion by FTIR spectroscopy, equilibrium swelling studies. Thermal and dynamical properties of the macromers and the resulting networks were studied by TGA, DSC and DMA techniques pre- and post-photocrosslinking. In contrast to the self-crosslinkability of the macromers, the crosslinking reaction was promoted more efficiently in the presence of NVP as a reactive diluent. This scrutiny showed that there is an optimum point for POSS concentration to obtain the maximum improvement in the network properties.