Photodegradation of electrospun PCL/TiO2 composites nanofibres

Electrospinning is the process of nanofibers formation under electrical field, where polymer solution or melt is being stretched by electrostatic forces. Nanometer dimension TiO2 nanoparticles have been recently proposed as attractive filler materials for biodegradable polymer matrices as it enhances cell attachment and proliferation on the composite surfaces. The degradation process extends into the polymer matrices through the diffusion of the reactive oxygen species. Resistance to UV light is an important factor for outdoor applications of polymeric materials. In this study polycaprolactone was electrospun into fibres with the addition of nano- and micro- TiO2 as well as TiO2 nanotubes. The photodegradation behavior of the electrospun PCL and PCL/TiO2 micro- and nano-composites fibers was investigated. The addition of micro TiO2 particles in the PCL slightly increased Tg of TiO2 while the addition of nano TiO2 (nTiO2) and Ti nanotubes (TiNT) did not affect on the Tg prior to UV irradiation. After UV irradiation, the Tg of the electrospun PCL/TiNT composite fibres was moved to a higher temperature. This behaviour could be explained by the lower mobility of the amorphous phase of PCL. TGA results showed that the slight improvement of thermal stability of electrospun PCL/ TiO2 composites fibres was obtained with the addition of micro- and nanoparticles of TiO2 as well as with TiNT. The results obtained from the SEM analysis suggests that the mTiO2 acts as a photocatalyst. This result suggests that in air any alkyl radicals will react with oxygen and formed hydroperoxides which can contribute to auto-catalytic reaction.TiO2 fillers in irradiated PCL/TiO2 composite led to the changes of some characteristic functional groups of PCL that was probably due to the photocatalytic activity of the TiO2 particles which accelerates the process of composite degradation.