Browsing by Author "University of Minnesota, Hillmyer Lab, Department of Chemistry"

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    Supporting data for "Efficient Polymerization of Methyl-ε-Caprolactone Mixtures to Access Sustainable Aliphatic Polyesters"
    (2020-02-26) Batiste, Derek, C; Meyersohn, Marianne S; Hillmyer, Marc A; Watts, Annabelle; hillmyer@umn.edu; Hillmyer, Marc A; University of Minnesota, Hillmyer Lab, Department of Chemistry
    These files contain primary data along with associated output from instrumentation supporting all results reported in Batiste et. al. "Efficient Polymerization of Methyl-ε-Caprolactone Mixtures to Access Sustainable Aliphatic Polyesters." In Batiste et. al. we found: Aliphatic polyesters are a versatile class of materials that can be sourced from bioderived feedstocks. Poly(γ-methyl-ε-caprolactone) (PγMCL) in particular can be used to make degradable thermoplastic elastomers (TPEs) with outstanding mechanical properties. PγMCL can potentially be manufactured economically from p-cresol, a component of lignin bio oils. A complication is that additional manufacturing processes are necessary to isolate pure cresol isomers. Using mixed feedstocks of cresol isomers to access the corresponding methyl substituted ε-caprolactone (MCL) monomer mixtures would convey economic advantages to sourcing these materials sustainably. Moreover, the use of organocatalysts in lieu of traditional tin-based catalysts averts issues with potential environmental and human toxicity. With these motivations in mind, we explored the ring-opening transesterification polymerization (ROTEP) of MCL mixtures and characterized the molecular, thermal and rheological properties of the resulting copolymers. The molar mass of MCL mixtures that would be obtained from meta- and para-cresol can be readily modulated. The thermal and rheological properties of these statistical co- and terpolymers were at parity with pure PγMCL homopolymer. The use of diphenyl phosphate (DPP) and dimethyl phosphate (DMP) as organocatalysts enabled access to these materials on reasonable polymerization timescales and have potential to improve sustainability in the synthesis of these polyesters.
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    Supporting data for Synthesis, microstructure, and properties of high molar mass polyglycolide copolymers with isolated methyl defects
    (2021-06-15) Altay, Esra; Jang, Yoon-Jung; Kua, Xiang Qi; Hillmyer, Marc; hillmyer@umn.edu; Hillmyer, Marc; University of Minnesota, Hillmyer Lab, Department of Chemistry
    An efficient, fast and reliable method for the synthesis of high molar mass polyglycolide (PGA) in bulk using bismuth (III) subsalicylate through ring-opening transesterification polymerization is described.The difference between the crystallization (Tc ≈ 180 °C) / degradation (Td ≈ 245 °C) temperatures and the melting temperature (Tm ≈ 222 °C) significantly impacts the ability to melt process PGA homopolymer. To expand these windows, the effect of copolymer microstructure differences through incorporation of methyl groups in pairs using lactide or isolated using methyl glycolide (10% methyl) as comonomers on the thermal, mechanical and barrier properties were studied. Structures of copolymers were characterized by Nuclear Magnetic Resonance (1H and 13C NMR) spectroscopies. Films of copolymers were obtained, and the microstructural and physical properties were analyzed. PGA homopolymers exhibited approximately 30 °C difference between Tm and Tc, which increased to 50 °C by incorporating up to 10% methyl groups in the chain while maintaining overall thermal stability. Oxygen and water vapor permeation values of solvent cast non-oriented films of PGA homopolymers were found to be 4.6 (cc.mil.m-2.d-1.atm-1) and 2.6 (g.mil.m-2.d-1.atm-1), respectively. Different methyl distributions in the copolymer sequence, provided through either lactide or methyl glycolide impacted the resulting barrier properties. At 10% methyl insertion using lactide as a comonomer significantly increased both O2 (32 cc.mil.m-2.d-1.atm-1) and water vapor (12 g.mil.m-2.d-1.atm-1) permeation. However, when methyl glycolide was utilized for methyl insertion at 10% Me content, excellent barrier properties for both O2 (2.9 cc.mil.m-2.d-1.atm-1) and water vapor (1.0 g.mil.m-2.d-1.atm-1) were achieved.