Defence Friso Versteeg: "Supercritical CO2 solution for polymer synthesis, purification and processing"

Promotors: 1 st Promotor: Prof Francesco Picchioni, 2 nd promotor: Prof Eric Heeres, 3 rd promotor: Dr Pablo Druetta

Abstract: One of the major challenges in polymer production technology is developing new processes that are more sustainable, cleaner, and environmentally friendly. Since the vast majority of these processes are conducted using volatile organic solvents, research into more sustainable methods focuses on finding safer, less harmful, and non-toxic solvent alternatives. In this thesis the use of supercritical solvents and more specifically, supercritical CO2 (scCO2), has been investigated as an alternative for polymer synthesis, processing and purification respectively. Furthermore, the bio renewable chemical α-methylene-γ-butyrolactone (α-MBL) is the key component in the polymers that are synthesized in the present work. Unique properties for α-MBL are the high glass transition temperature (Tg) of 195 °C and the excellent chemical resistance. In the first four chapters the possibility of replacing fossil based building blocks for the biorenewable compound (α-MBL) is explored. In the end it was deemed a success by making partly based rubbers that are comparable to commercially available synthetic rubbers such as styrene-butadiene-styrene (SBS). In the final two chapter the use of scCO2 for polymer purification and processing is explored. By using scCO2 as an extraction solvent bulk polymers such as poly(methyl methacrylate) and polystyrene were stripped of 99.99% of monomer impurifications making this an environmentally friendly alternative. Finally the solubility of scCO2 in polystyrene was determined and mathematically modelled. This was done as scCO2 can act as a foaming agent for polystyrene. The mathematical model proved to be very accurate in predicting the solubility and swelling of the polystyrene under supercritical conditions.

Dissertation