Browsing by Author "Kua, Xiang Qi"
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Item Step-Growth Polyesters with Biobased (R)-1,3-Butanediol(2020-08-26) DeRosa, Christopher A; Kua, Xiang Qi; Bates, Frank S; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; University of Minnesota, Department of ChemistryThese files contain primary data along with associated output from "Step-Growth Polyesters with Biobased (R)-1,3-Butanediol" by Hillmyer et al. We present the synthesis and characterization of polymers containing 1,3-butanediol, also known as butylene glycol. Butylene glycol (BG) can be prepared from petroleum or sugar-based feedstocks. Petrol-based BG (petrol-BG) is isolated as a racemic mixture, whereas the bio-based BG from sugar that we utilized (Bio-BG), is enantiopure upon purification (>99.7%). In the presence of a titanium catalyst, polyesters were prepared by transesterification polymerization between petrol- or Bio-BG and various aliphatic and aromatic diacid derivatives. Polymers were analyzed by size-exclusion chromatography (SEC), 1H NMR and 13C NMR spectroscopies, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The synthesized polyesters were statistical in nature, according to 13C NMR spectroscopy, a result of the asymmetric nature of the BG-starting material. As a result, many of the polyesters were amorphous in nature with low thermal glass transitions (Tg) and no melting points (Tm). In many of the polyester derivatives, the racemic petrol-based and enantiopure bio-based BG polymers were nearly identical in thermal performance. Differences arose in semi-crystalline polyesters with long, aliphatic backbones (e.g., 1,14-tetradecanediocic acid; C14 diacid) or regioregular 4-hydroxybenzoate polyesters. This suggests the polymer microstructure (statistical versus sequenced) and the optical activity (racemic versus enantiopure) are important determinates in establishing the structure-property relationships in BG-containing polyesters. This work establishes synthetic protocols and the foundation for materials based on BG-containing polymers.Item 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 ChemistryAn 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.