Browsing by Author "Hillmyer, Marc A"

Now showing 1 - 20 of 23
  • Thumbnail Image
    Item
    Data for Alkyl Substituted Polycaprolactone Poly(Urethane-Urea)s as Mechanically-Competitive and Chemically-Recyclable Materials
    (2024-07-18) Pfau-Cloud, Michaela R; Batiste, Derek C; Kim, Hee Joong; Ellison, Christopher J; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Group
    We report the mechanical performance and chemical recycling advantages of implementing alkyl-substituted poly(ε-caprolactones) (PCLs) as soft segments in thermoplastic poly(urethane-urea) (TPUU) materials. Poly(4-methylcaprolactone) (P4MCL) and poly(4-propylcaprolactone) (P4PrCL) were prepared, reacted with isophorone diisocyanate, and chain-extended with water to form TPUUs. The resulting materials’ tensile properties were similar to or superior to a commercially available polyester thermoplastic poly(urethane), and had superior elastic recovery compared to a PCL analogue due to the non-crystalline nature of P4MCL and P4PrCL. Additionally, monomers were recovered from the TPUU materials in high yields via ring-closing depolymerization using a reactive distillation approach at elevated temperature and reduced pressure (240–260 °C, 25-140 mTorr) with zinc chloride (ZnCl2) as the catalyst. The thermodynamics of polymerization were estimated using Van’t Hoff analyses for 4MCL and 4PrCL; these results indicated that the propyl group in 4PrCL results in a lower practical ceiling temperature (Tc) for P4PrCL.
  • Thumbnail Image
    Item
    Data for Crystallinity-independent toughness in renewable poly(L-lactide) triblock plastics
    (2024-03-18) Krajovic, Daniel M; Haugstad, Greg; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Research Group
    Poly(L-lactide) (PLLA)’s broad applicability is hindered by its brittleness and slow crystallization kinetics. Among the strategies for developing tough, thermally resilient PLLA-based materials, the utilization of neat PLLA block polymers has received comparatively little attention despite its attractive technological merits. In this work, we comprehensively describe the microstructural, thermal, and mechanical properties of two compositional libraries of PLLA-rich PLLA-b-poly(γ-methyl-ε-caprolactone) (PγMCL)-b-PLLA (“LML”) triblock copolymers. The rubbery PγMCL domains microphase separate from the matrix in the melt and intercalate between PLLA crystal lamellae on cooling. Despite the mobility constraints associated with mid-block tethering, the PLLA end-blocks crystallize as rapidly as a PLLA homopolymer control of similar molar mass. Independent of their degree of crystallinity, LML triblocks exhibit vastly improved tensile toughnesses (63-113 MJ m-3) over that of PLLA homopolymer (1.3-2 MJ m-3), with crystallinities of up to 55% and heat distortion temperatures (HDTs) as high as 148 °C. We investigated the microstructural origins of this appealing performance using X-ray scattering and microscopy. In the case of a largely amorphous PLLA matrix, the PγMCL domains cavitate to enable concurrent PLLA shear yielding and strain-induced crystallization. In highly crystalline PLLA matrices, PγMCL facilitates a lamellar-to-fibrillar transition during tensile deformation, the first such transition reported for PLLA drawn at room temperature. These results highlight the unique attributes of PLLA block polymers and prompt future architectural and processing optimizations to achieve ultratough, high-HDT PLLA block polymer plastics after a simple thermal history on economical timescales.
  • Thumbnail Image
    Item
    Data for Order and Disorder in ABCA′ Tetrablock Terpolymers
    (2020-11-16) Radlauer, Madalyn R; Arora, Akash; Matta, Megan E; Bates, Frank S; Hillmyer, Marc A; Dorfman, Kevin D; dorfman@umn.edu; Dorfman, Kevin D; Dorfman Group
  • No Thumbnail Available
    Item
    Data from: Thermal Processing of Diblock Copolymer Melts Mimics Metallurgy
    (2017-05-22) Kim, Kyungtae; Schulze, Morgan W; Arora, Akash; Lewis III, Ronald M; Hillmyer, Marc A; Dorfman, Kevin D; Bates, Frank S; dorfman@umn.edu; Dorfman, Kevin D
    Small-angle x-ray scattering experiments conducted with compositionally asymmetric low molar mass poly(isoprene)-b-poly(lactide) diblock copolymers reveal an extraordinary thermal history dependence. The development of distinct periodic crystalline or aperiodic quasicrystalline states depends on how specimens are cooled from the disordered state to temperatures below the order-disorder transition temperature. Whereas direct cooling leads to the formation of documented morphologies, rapidly quenched samples that are then heated from low temperature form the hexagonal C14 and cubic C15 Laves phases commonly found in metal alloys. Self-consistent mean-field theory calculations show that these, and other associated Frank-Kasper phases, have nearly degenerate free energies, suggesting that processing history drives the material into long-lived metastable states defined by self-assembled particles with discrete populations of volumes and polyhedral shapes.
  • Thumbnail Image
    Item
    Entropically-driven macrolide polymerizations for the synthesis of aliphatic polyester copolymers using titanium isopropoxide
    (2019-03-11) Amador, Adrian G; Watts, Annabelle; Neitzel, Angelika, E; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Research Group
    Thermal and mechanical properties of sustainable aliphatic polyesters can be tuned through the synthesis of copolymers. The synthesis of two 14-membered macrolides are reported: a cyclic tetraester with alternating lactic acid (LA) and 3-hydroxypropionic acid (3HP) units and a cyclic diester with alternating glycolic acid (GA) and 2-methyl-1,3-propanediol (2MD) units. Ring-opening transesterification polymerization (ROTEP) of these macrolides to yield poly(LA-stat-3HP) and poly(GA-alt-2MD), respectively, were found to be modestly endothermic (ΔHp° = 2.0 kJ mol-1 and 0.5 kJ mol-1, respectively) and endoentropic (ΔSp° = 27 J mol-1 K-1 and 23 J mol-1 K-1, respectively). Inexpensive and non-toxic titanium isopropoxide Ti(Oi-Pr)4 functions as an active catalyst for these entropically-driven ROTEPs, achieving high conversions (> 90%) in under 1 h. The polymerizations exhibit control over molar mass with dispersity values < 1.7. P(GA-alt-2MD) is an amorphous polymer with a low glass transition temperature near −30 °C. P(LA-co-3HP) exhibits a glass transition temperature up to 13 °C and depending on the regioregularity, exhibits a melting temperature up to 96 °C.
  • Thumbnail Image
    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 Chemistry
    These 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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Supporting Data for "From Order to Disorder: Computational Design of Triblock Amphiphiles with 1 nm Domains"
    (2020-07-06) Shen, Zhengyuan; Chen, Jingyi L; Vernadskaia, Viktoriia; Ertem, S Piril; Mahanthappa, Mahesh K; Hillmyer, Marc A; Reineke, Theresa M; Lodge, Timothy P; Siepmann, J Ilja; siepmann@umn.edu; Siepmann, J Ilja; Materials Research Science & Engineering Center (MRSEC)
    Data including input/output and restart files for all the systems, analysis codes (python, fortran, cpp), and figures in the paper "From Order to Disorder: Computational Design of Triblock Amphiphiles with 1 nm Domains." Sample molecular dynamics trajectories pieces are provided due to the extremely long simulation trajectories.
  • Thumbnail Image
    Item
    Supporting data for Chemically Recyclable Linear and Branched Polyethylenes Synthesized from Stoichiometrically Self-balanced Telechelic Polyethylenes
    (2024-02-01) Jang, Yoon-Jung; Nguyen, Sam; 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 of the referenced paper.
  • Thumbnail Image
    Item
    Supporting data for Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers
    (2018-02-06) Haugan, Ingrid N; Maher, Michael J; Chang, Alice B; Lin, Tzu-Pin; Grubbs, Robert H; Hillmyer, Marc A; Bates, Frank S; bates001@umn.edu; Bates, Frank S
    These files contain data along with associated output from instrumentation supporting all results reported in Haugan et. al. "Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers." In Haugan et. al. we found: The linear viscoelastic behavior of poly(norbornene)-graft-poly(±-lactide) was investigated as a function of grafting density and overall molar mass. Eight sets of polymers with grafting densities ranging from 0–100% were synthesized by living ring-opening metathesis copolymerization. Within each set, the graft chain molar mass and spacing between grafts were fixed while the total backbone length was varied. Dynamic master curves reveal that these polymers display Rouse and reptation dynamics with a sharp transition in the zero-shear viscosity data demonstrating that grafting density strongly impacts the entanglement molar mass. The entanglement modulus (Ge) scales with inverse grafting density (ng) as Ge ~ ng1.2 and Ge ~ ng0 in accordance with scaling theory in the high and low grafting density limits, respectively. However, a sharp transition between these limiting behaviors occurs, which does not conform to existing theoretical models for graft polymers. A molecular interpretation based on thin flexible chains at low grafting density and thick semiflexible chains at high grafting density anticipates the sharp transition between the limiting dynamical regimes.
  • Thumbnail Image
    Item
    Supporting data for Crosslinked polyolefins through tandem ROMP/hydrogenation
    (2024-03-14) Hillmyer, Marc A; Sample, Caitlin S; Hoehn, Brenden D; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Research Group
    These files contain primary data along with associated output from instrumentation supporting all results reported in Sample et al. "Crosslinked Polyolefins Through Tandem ROMP/Hydrogenation". Crosslinked polyolefins have important advantages over their thermoplastic analogues, particularly improved impact strength and abrasion resistance, as well as increased chemical and thermal stability; however, most strategies for their production involve post-polymerization crosslinking of polyolefin chains. Here, a tandem ring-opening metathesis polymerization (ROMP)/hydrogenation approach is presented. Cyclooctene (COE)-co-dicyclopentadiene (DCPD) networks are first synthesized using ROMP, after which the dispersed Ru metathesis catalyst is activated for hydrogenation through addition of hydrogen gas. The reaction temperature for hydrogenation must be sufficiently high to allow mobility within the system, as dictated by thermal transitions (i.e., glass and melting transitions) of the polymeric matrix. COE-rich materials exhibit branched-polyethylene-like crystallinity (25% crystallinity) and melting points (Tm = 107 °C), as well as excellent ductility (>750 % extension), while majority DCPD materials are glassy (Tg = 84 °C) and much stiffer (E = 710 MPa); all materials exhibit high tensile toughness. Importantly, hydrogenation of olefins in these crosslinked materials leads to notable improvements in oxidative stability, as saturated networks do not experience the same substantial degradation of mechanical performance as their unsaturated counterparts upon prolonged exposure to air at high temperature.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Supporting data for Functionalized Polymersomes from a Polyisoprene-Activated Polyacrylamide Precursor
    (2021-01-20) Werber, Jay R; Peterson, Colin; Van Zee, Nicholas J; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Research Group
    These files contain primary data along with associated output from instrumentation supporting all results reported in the associated manuscript referenced below. In this study, polymersomes with novel surface chemistries were synthesized using a post-polymerization modification approach, which enabled us to characterize the soluble precursor polymers and then modify the polymers to create highly amphiphilic block polymers.
  • Thumbnail Image
    Item
    Supporting Data for High Performance Star Block Aliphatic Polyester Thermoplastic Elastomers using PDLA-b-PLLA Stereoblock Hard Domains
    (2023-09-07) Liffland, Stephanie; Kumler, Margaret; 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 "High Performance Star Block Aliphatic Polyester Thermoplastic Elastomers using PDLA-b-PLLA Stereoblock Hard Domains" by Liffland et al. Star block (ABC)4 terpolymers consisting of a rubbery poly(γ-methyl-ε-caprolactone) (PγMCL) (C) core and hard poly(L-lactide) (PLLA) (B) and poly(D-lactide) (PDLA) (A) end-blocks with varying PDLA to PLLA block ratios were explored as high-performance, sustainable, aliphatic polyester thermoplastic elastomers (APTPEs). The stereocomplexation of the PDLA/PLLA blocks within the hard domains provided the APTPEs with enhanced thermal stability and an increased resistance to permanent deformation compared to non-stereocomplex analogs. Variations in the PDLA:PLLA block ratio yielded tunable mechanical properties likely due to differences in the extent and location of stereocomplex crystallite formation as a result of architectural constraints. This work highlights the improvements in mechanical performance due to stereocomplexation within the hard domains of these APTPEs and the tunable nature of the hard domains to significantly impact material properties, furthering the development of sustainable materials that are competitive with current industry standard materials.
  • Thumbnail Image
    Item
    Supporting data for Impact of macromonomer molar mass and feed composition on branch distributions in model graft copolymerizations
    (2021-12-07) Zografos, Aristotelis; Lynd, Nathaniel A; Bates, Frank S; 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 the referenced manuscript. Graft polymers are useful in a versatile range of material applications. Understanding how changes to the grafted architecture, such as the grafting density (z), the side-chain degree of polymerization (Nsc), and the backbone degree of polymerization (Nbb), affect polymer properties is critical for accurately tuning material performance. For graft-through copolymerizations, changes to Nsc and z are controlled by the macromonomer degree of polymerization (NMM) and initial fraction of the macromonomer in the feed (fMM0), respectively. We show that changes to these parameters can influence the copolymerization reactivity ratios and, in turn, impact the side-chain distribution along a graft polymer backbone. Poly((±)-lactide) macromonomers with NMM values as low as ca. 1 and as high as 72 were copolymerized with a small-molecule dimethyl ester norbornene comonomer over a range of fMM0 values (0.1 ≤ fMM0 ≤ 0.8) using ring opening metathesis polymerization (ROMP). Monomer conversion was determined using 1H nuclear magnetic resonance spectroscopy, and the data were fit using terminal and non-terminal copolymerization models. The results from this work provide essential information for manipulating Nsc and z, while maintaining synthetic control over the side-chain distribution for graft-through copolymerizations.
  • No Thumbnail Available
    Item
    Supporting data for Polymeric Microcapsules as Robust Mimics of Emulsion Liquid Membranes for Selective Ion Separations
    (2022-11-14) Werber, Jay R; Hillmyer, Marc A; Peterson, Colin H; Stipanic, Dean F; hillmyer@umn.edu; Hillmyer, Marc A; University of Minnesota Hillmyer Research Group
    Experimental and Modeling data in support of Published Article "Polymeric Microcapsules as Robust Mimics of Emulsion Liquid Membranes for Selective Ion Separations" in Environmental Science & Technology
  • Thumbnail Image
    Item
    Supporting data for Regio- and stereoregular EVOH Copolymers from ROMP as Designer Barrier Materials
    (2024-04-03) Hillmyer, Marc A; Dingwell, Claire; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Research Group
    This work aimed to decrease the water permeability (PH2O), while simultaneously maintaining low oxygen permeability (PO2) in ethylene vinyl alcohol (EVOH) based copolymers by introducing high levels of backbone regioregularity and stereoregularity. Both regioregular atactic and isotactic EVOH samples with 75 mol% ethylene were prepared by a ring-opening metathesis polymerization (ROMP)-hydrogenation-deprotection approach and then compared to commercial EVOH(44) (containing 44 mol% ethylene) as a low PO2 standard with poor water barrier characteristics (i.e., high PH2O). The high levels of regioregularity and stereoregularity in these copolymers increased melting temperature (Tm), degree of crystallinity (χc), and glass transition temperature (Tg) compared to less regular structures. EVOH(44) demonstrated the highest Tm, but lower χc and Tg values as compared to the ROMP-derived polymers. Wide-angle X-ray scattering showed that semi-crystalline EVOH(44) exhibited a monoclinic structure characteristic of commercial materials, while ROMP-derived polymers displayed an intermediate structure between monoclinic and orthorhombic. Tensile testing showed that isotacticity resulted in brittle mechanical behavior, while the atactic and commercial EVOH(44) samples had higher tensile toughness values. Although EVOH(44) had the lowest PO2 of the samples explored, the atactic and tough ROMP-derived polymer approached this value of PO2 while having a PH2O over 3 times lower than commercial EVOH(44).
  • Thumbnail Image
    Item
    Supporting data for Star-to-bottlebrush transition in extensional and shear deformation of unentangled polymer melts
    (2023-03-15) Zografos, Aristotelis; All, Helena A; Chang, Alice B; Hillmyer, Marc A; Bates, Frank S; bates001@umn.edu; Bates, Frank S; University of Minnesota Department Chemical Engineering and Material Science
    These files contain primary data along with associated output from instrumentation supporting all results reported in Zografos et al. "Star-to-bottlebrush transition in extensional and shear deformation of unentangled polymer melts." A series of model poly((±)-lactide) (PLA) graft copolymers were synthesized using ring-opening metathesis polymerization and used to probe the star-to-bottlebrush transition in shear and extensional flows. Ten samples with backbone degrees of polymerization 10 < Nbb < 430, each containing one PLA side chain of length Nsc = 72 per two backbone repeat units, were investigated using small-amplitude oscillatory shear (SAOS) and extensional rheometry measurements. The star-like to bottlebrush transition was identified at Nbb = 50-70 using SAOS. In extension, melt strain hardening is absent in the star-like melts (Nbb < 50) but is prominent in the bottlebrush limit (Nbb > 70). The onset of melt strain hardening occurs at a timescale equivalent to the Rouse time of the backbone. A molecular interpretation of these results builds upon recent speculation related to strain-induced increases in interchain friction in bottlebrush polymers. These findings will be useful in designing bottlebrush melts to strain harden, which is critical in various types of processing methods involving extensional flows, including foaming, 3D printing, and film-blowing.
  • Thumbnail Image
    Item
    Supporting Data for Tandem ROMP/Hydrogenation Approach to Hydroxy-Telechelic Linear Polyethylene
    (2022-04-11) Sample, Caitlin S; Kellstedt, Elizabeth A; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Group
    These files contain data along with associated output from instrumentation supporting all results reported in Sample et. al. "Tandem ROMP/Hydrogenation Approach to Hydroxy-Telechelic Linear Polyethylene." In Sample et. al. we found: Hydroxy-telechelic polycycloalkenamers have long been synthesized using ring-opening metathesis polymerization (ROMP) in the presence of an acyclic olefin chain-transfer agent (CTA); however, this route typically requires protected diols in the CTA due to the challenge of alcohol-mediated degradation of ruthenium metathesis catalysts that can not only deactivate the catalysts but also compromise the CTA. We demonstrate the synthesis and implementation of a new hydroxyl-containing CTA in which extended methylene spacers isolate the olefin and alcohol moieties to mitigate decomposition pathways. This CTA enabled the direct ROMP synthesis of hydroxy-telechelic polycyclooctene with controlled chain lengths dictated by the initial ratio of monomer to CTA. The elimination of protection/deprotection steps resulted in improved atom economy. Subsequent hydrogenation of the backbone olefins was performed by a one-pot, catalytic approach employing the same ruthenium alkylidene catalyst used for the initial ROMP. The resultant approach is a stream-lined, atom-economic, and low-waste route to hydroxy-telechelic linear polyethylene that uses a green solvent, succeeds with miniscule quantities of catalyst (0.005 mol%), and requires no additional purification steps.
  • Thumbnail Image
    Item
    Supporting data for Tough Polycyclooctene Nanoporous Membranes from Etchable Block Copolymers
    (2023-12-14) Hoehn, Brenden D; Kellstedt, Elizabeth A; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Research Group
    These files contain primary data along with associated output from instrumentation supporting all results reported in Hoehn et al. "Tough Polycyclooctene Nanoporous Membranes from Etchable Block Copolymers". In Hoehn et al. we found porous materials with pore dimensions of the nanometer length scale are useful as nanoporous membranes. ABA triblock copolymers are convenient precursors to such nanoporous materials if the end blocks are easily degradable (e.g., polylactide or PLA) in thin films leaving nanoporous polymeric membranes (NPMs). The membrane properties are dependent on midblock monomer structure, triblock copolymer composition, overall molar mass, and polymer processing conditions. Polycyclooctene (PCOE) NPMs were prepared using this method, with tunable pore sizes on the order of tens of nanometers. Solvent casting was shown to eliminate film defects and allowed achievement of superior mechanical properties over melt processing techniques, and PCOE NPMs were found to be very tough, a major advance over previously reported NPMs. Oxygen plasma etching was used to remove the surface skin layer to obtain membranes with higher surface porosity, membrane hydrophilicity, and flux of both air and water. This is a straightforward method to reliably produce highly tough NPMs with high levels of porosity and hydrophilic surface properties.