Dielectric study of polystyrene/polycaprolactone composites prepared by miniemulsion polymerization

Composite of polystyrene (PS) and a biodegradable polymer, polycaprolactone (PCL), has been prepared by miniemulsion polymerization technique. In the procedures, different amounts of commercial PCL were added during polymerization of PS in presence of sodium lauryl sulfate (SLS) as a surfactant. Formation of PS and PS/PCL nanoparticles was confirmed by Transmission Electron Microscope (TEM) and their structure was investigated using Fourier Transform Infra-Red (FTIR)and UV spectrometry. Encapsulation of PCL particles yielded nanoparticles of gradual enlargement in size as revealed by zeta sizer. However, significant information about the molecular dynamics within the composite and charge mobility can be realized by Broadband dielectric spectroscopy (BDS). So that, BDShas been employed to investigate the electrical and dielectric behavior of the considered composites over a wide range of frequency and temperature. It was found that the dielectric properties of the composites seem to be mainly due to the PS shell with no significant effect for presence of PCL in the core. The linear decrease of the real part of conductivity of the prepared blends with decreasing frequency just like the perfect insulator confirmed the encapsulation feature of the structure. The new materials can find applications in packaging, household beside biomedical fields.