Degradation biosensing performance of polymer blend carbon nanotubes (CNTs) nanocomposites

Abstract

This paper describes the hydrolytic degradation and sensing behavior of poly (lactic acid) (PLA)/poly (ethylene oxide) (PEO)/carbon nanotubes (CNTs) nanocomposites in neutral phosphate-buffered saline (PBS) solution. Degradation sensing is performed based on the variations of electrical conductivity due to the degradation of PLA and PEO phases. The molecular weights of polymers, the morphologies of polymer blends and nanocomposites, the chemical bonds and the crystalline structures of polymers are analyzed before and during the degradation process. CNTs promote the degradation of PLA/PEO blends and the conductivity of all samples improves with increased degradation time. The samples with high PEO and CNTs concentrations exhibit a considerable sensing, because they show a large variation in conductivity during degradation. A matrix-droplet structure forms in the samples before and after degradation, where PEO particles are dispersed in a continuous PLA phase. Both amorphous and crystalline regions of PEO experience the hydrolytic degradation, but CNTs largely control the crystallinity of PLA suggesting the localization of CNTs in the PLA phase.