Kinetics, Synthesis and Characterization of copolymers containing the bio-renewable monomer g-methyl-a-methylene-g-butyrolactone (MeMBL)
Cockburn, A. Robert
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The bio-renewable monomer γ-methyl-α-methylene-γ-butyrolactone (MeMBL) has been thoroughly investigated in this thesis. MeMBL is a relatively unstudied monomer that had received little attention since the early 1980’s but has become a subject of renewed interest since a process to produce it from biomass derivatives was developed in 2004. The principle interest with this monomer aside from the “green” potential associated with bio-renewables results from its structure being cyclically analogous to methyl methacrylate (MMA) as well as improved solvent resistance and a high (215oC+) glass transition temperature (Tg) compared to most petroleum sourced acrylics. There are three major areas of focus in this work, examining polymerization kinetics, synthesis and polymer characterization. The polymerization kinetics of MeMBL were investigated with a variety of petroleum sourced monomers. MeMBL is in all cases preferentially incorporated into copolymers, presenting challenges for composition control. Preliminary investigations of aqueous phase polymerizations of MeMBL were problematic and led to investigations of organic phase polymerizations. The dispersion polymerization method was used to produce copolymers of MeMBL and MMA; during the study we obtained new insight into the mechanisms of particle nucleation and growth. With the acquired knowledge of MeMBL polymerization kinetics, the dispersion technique was used to produce MeMBL/MMA copolymers of controlled composition by semibatch for characterization studies. The addition of MeMBL raises polymer Tg and lowers molecular weight, but due to unexpected difficulties in processing MeMBL copolymers, mechanical properties could not be investigated in this study. Future work may need to revisit other polymerization techniques in order to produce processable polymers to test whether or not MeMBL might be a suitable alternative to petroleum sourced monomers that is capable of extending the range and utility of acrylics.