Browsing by Subject "polyester"

Now showing 1 - 6 of 6
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    Degradable Materials from Sugar-Derived Feedstocks
    (2019-01) Lillie, Leon
    Sugar-derived molecules have excellent potential to serve as building blocks in the development of sustainable polymers with high performance and rich functionality. This thesis focuses on the utilization of carbohydrate-derived molecules (bicyclic sugar derivatives and sugar metabolites) to enhance the degradability of polymeric materials. The first area of research presented describes the synthesis of a novel GDL-based α,ω-diene (glucarodilactone 10-undecenoate, GDLU). This molecule and its congener (isosorbide undecenoate, IU), were found to be highly suitable monomers for acyclic diene metathesis polymerization and were used to produce a family of homopolymers and copolymers of various GDLU:IU ratios. The structure/property implications of these similar sugar-derived diols on the materials physical performance and hydrolytic stability were explored. The second area of research expanded the usage of GDLU to a new class of materials, poly(ester-thioethers), with the use of photo-initiated thiol-ene polymerization. The impact of dithiol chemistry on material thermal and mechanical properties were investigated. Finally, the third area of research details the synthesis of novel methacrylic anhydride-like monomers obtained from the two-step synthetic modification of itaconic acid. These monomers were polymerized via thiol-ene polymerizations to obtain degradable, polyanhydride-based thermoset materials, with rapid neutral water degradation.
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    Renewable Aliphatic Polyester Block Polymer Thermoplastic Elastomers
    (2014-04) Martello, Mark
    The performance of thermoplastic elastomers is predicated on their ability to form mechanically tough physically crosslinked elastomeric networks at low temperatures and be able to flow at elevated temperatures. This dissertation focuses on renewable aliphatic polyester block polymers with amorphous polylactide (PLA) and their performance as TPEs. The goal of this work was to enhance the mechanical toughness of PLA containing TPEs; fundamental properties ranging from chemical composition and phase behavior, molecular architecture and melt processability, to melt polymerization strategies were investigated. ABA triblock polymers with PLA end-blocks and rubbery mid-blocks from substituted lactones comprised of poly(6-methyl-ε-caprolactone)(PMCL), poly(δ-decalactone), and poly(ε-decalactone)(PDL) were produced by sequential ring-opening polymerizations in the bulk. The bulk microstructure of symmetric PLA-PMCL-PLA and PLA-PDL-PLA triblock polymers formed long-range ordered morphologies and the interaction parameter of the repeat units was determined. High molar mass triblocks exhibited elastomeric behavior with good tensile strengths and high elongations. Small triblocks were coupled to produced (PLA-PDL-PLA)n multiblock polymers with high molar mass and accessible order-disorder transitions allowing for melt processing via injection molding. The mechanical toughness of the multiblocks was comparable to the high molar mass triblocks. The controlled polymerization of renewable δ-decalactone was accomplished with an organocatalyst at low temperatures in the bulk to maximize the equilibrium conversion of the monomer.
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    Supporting data for Dynamic Aliphatic Polyester Elastomers Crosslinked with Aliphatic Dianhydrides
    (2023-01-27) Meyersohn, Marianne S; Haque, Farihah M; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc, A; University of Minnesota, Department of Chemistry
    These files contain primary data along with associated output from instrumentation supporting all results reported in Meyersohn, M. et. al. "Dynamic Aliphatic Polyester Elastomers Crosslinked with Aliphatic Dianhydrides." In Meyersohn, M. et. al. we found: Chemically crosslinked elastomers are a class of polymeric materials with properties that render them useful as adhesives, sealants, and in other engineering applications. Poly(γ-methyl-ε-caprolactone) (PγMCL) is a hydrolytically degradable and compostable aliphatic polyester that can be biosourced and exhibits competitive mechanical properties to traditional elastomers when chemically crosslinked. A typical limitation of chemically crosslinked elastomers is that they cannot be reprocessed; however, incorporation of dynamic covalent bonds (DCBs) can allow for bonds to reversibly break and reform under an external stimulus, usually heat. In this work we the study dynamic behavior and mechanical properties of PγMCL elastomers synthesized from aliphatic dianhydride crosslinkers. The crosslinked elastomers in this work were synthesized using the commercially available crosslinkers, 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA), and 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and three-arm hydroxy-telechelic PγMCL star polymers. Stress relaxation experiments on the crosslinked networks showed an Arrhenius dependence of viscosity with temperature with an activation energy of 118 ± 8 kJ/mol, which agrees well with the activation energy of the exchange chemistry obtained from small molecule model studies. Dynamic mechanical thermal analysis and rheological experiments confirmed the dynamic nature of the networks and provided insight into the mechanism of exchange (i.e., associative, or dissociative). Tensile testing showed that these materials can exhibit high strains at break and low Young’s moduli, characteristic of soft, strong elastomers. By controlling the exchange chemistry and understanding the effect of macromolecular structure on mechanical properties, we prepared high performing elastomers that can be rapidly reprocessed at moderately elevated temperatures.
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    Supporting Data for Ring-Opening Copolymerizations of a CO2-derived δ-Valerolactone with ε-Caprolactone and L-Lactide
    (2024-05-30) Anderson, Ryan A; Fine, Rachel F; Rapagnani, Rachel M; Tonks, Ian A; itonks@umn.edu; Tonks, Ian; University of Minnesota, Tonks group
    These files contain primary data along with associated output from instrumentation supporting all results reported in Anderson et. al. Ring-Opening Copolymerizations of a CO2-derived δ-Valerolactone with ε-Caprolactone and L-Lactide. This work has expanded the synthetic polymer chemistry of the CO2-derived lactone EtVP through ring-opening co-polymerizations with ε-CL and LLA. Polymer properties and microstructures could be tuned through concurrent and se-quential copolymerization strategies, which led to the formation of either block, gradient, or random copolymers. ε-CL block copolymers resulted in semi-crystalline polymers regardless of the molar ratio employed. For LLA, copolymers remained amorphous, and mechanical testing showed improved elasticity relative to PLLA. Furthermore, ε-CL and LLA copolymers could be chemically recycled back to monomer utilizing Sn(Oct)2. While this work lays the foundation for EtVP-based copolymers, investigation into triblocks and other end-of-life options may further improve the potential ap-plications of these CO2-based (co)polymers.
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    Supporting Data for Tunable and Recyclable Polyesters from CO2 and Butadiene
    (2021-10-22) Rapagnani, Rachel M; Dunscomb, Rachel J; Fresh, Alexandra A; Tonks, Ian A; itonks@umn.edu; Tonks, Ian A; University of Minnesota, Department of Chemistry, Tonks group
    These files contain primary data along with associated output from instrumentation supporting all results reported in the referenced manuscript. Findings include: an alternate route to tunable, recyclable polyesters derived from CO2 and butadiene via an intermediary lactone, 3-ethyl-6-vinyltetrahydro-2H-pyran-2-one. Catalytic ring-opening polymerization of the lactone by 1,5,7-triazabicyclo[4.4.0]dec-5-ene yields polyesters with molar masses up to 13.6 kg/mol and pendent vinyl sidechains that can undergo post-polymerization functionalization. The polymer has a low ceiling temperature of 138 ºC, allowing for facile chemical recycling. These results mark the first example of a well-defined polyester derived solely from CO2 and olefins, expanding access to new feedstocks that were once considered unfeasible.
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    Supporting Information for Engineering Aliphatic Polyester Block Copolymer Blends for Hydrolytically Degradable Pressure Sensitive Adhesives
    (2025-01-06) Shuang, Liang; Krajovic, Daniel M; Hoehn, Brenden D; Ellison, Chris J; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc; Hillmyer and Ellison groups
    This work aimed to explore aliphatic polyester triblock copolymers of poly(L–lactide)–block–poly(γ–methyl–ε–caprolactone)–block–poly(L–lactide) (LML) and associated blends with renewable tackifier in pressure-sensitive adhesive (PSA) formulations and investigate effects of tackifier, composition, and processing history on microstructural, thermal, mechanical, and adhesive properties of the PSAs. After solvent casting and two–step annealing at 170 °C for 60 min and 100 °C for 5 min, LML–based PSAs showed stable and competitive adhesion properties when compared to commercial PSAs, which we attribute to both microphase separation and crystallinity in the poly(L–lactide) end blocks. Moreover, theses LML–based PSA formulations are hydrolytically degradable into water soluble or dispersible compounds at 45 ℃ under basic conditions within 30 days, offering the possibility of sustainable end–of–life scenarios for example through industrial composting.