Polystyrene–mesoporous diatomite composites produced by in situ activators regenerated by electron transfer atom transfer radical polymerization

Abstract

Mesoporous diatomite platelets were employed to synthesize different polystyrene/diatomite composites. Diatomite platelets were used for in situ polymerization of styrene by activators regenerated by electron transfer for atom transfer radical polymerization to synthesize tailor-made polystyrene nanocomposites. Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) were employed for evaluating some inherent properties of pristine diatomite platelets. Nitrogen adsorption/desorption isotherms are applied to examine surface area and structural characteristics of the diatomite platelets. Evaluation of pore size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography respectively. Addition of 3 wt% pristine mesoporous diatomite leads to increase of conversion from 85 to 94%. The molecular weight of polystyrene chains increases from 13 498 to 14 943 g mol⁻¹ by addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increase from 1.13 to 1.37. Appropriate agreement between theoretical and experimental molecular weight in combination with low PDI values can appropriately demonstrate the living nature of the polymerization. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 92.6 to 97.8 °C by adding 3 wt% of mesoporous diatomite platelets.