Somaieh Salehpour

Biodiesel: a green polymerization solvent

In an effort to use clean technologies, fatty acid methyl esters (FAME) produced from canola have been used as a polymerization solvent. Solution polymerizations of four commercially important monomers have been studied using FAME as a solvent. A series of methyl methacrylate (MMA), styrene (Sty), butyl acrylate (BA) and vinyl acetate (VAc) homopolymerizations in FAME were carried out at 60 °C at different solvent concentrations. Chain transfer to solvent rate constants were obtained using the Mayo method. The transfer constants increased in the order: MMA < Sty < BA < VAc. Under the conditions studied, the MMA solution polymerization in FAME was observed to behave as a precipitation polymerization. The estimated chain transfer to solvent rate constants were employed in a polymerization simulator to predict the polymerization rates and average molecular weights.

Application Properties of Stimuli-Responsive Polyglycerol Hydrogels

Transient state swelling behavior and swelling kinetics of novel stimuli-responsive polyglycerol hydrogels were studied at 293, 310 and 333 K. Depending on temperature, Fickian or anomalous diffusion behavior was observed. Mechanical properties of the hydrogels in the swollen and dry states were investigated and the average molecular weight between crosslinks was calculated. To assess the potential for biodegradation of hydrogels, initial swelling behavior in phosphate buffered saline (PBS) solution and mass loss profiles as a function of degradation time were investigated over a period of 30 days. All swelling behavior, mechanical properties and degradations were clearly affected by the degree of cross-linking. The hydrophilicity and biodegradability of polyglycerol hydrogels make them suitable for pharmaceutical, biomedical and biotechnological applications. They could potentially serve as a substitute for common fossil-based hydrogels such as poly(ethylene glycol) and poly(vinyl alcohol) hydrogels.