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Browsing by Author "Ellison, Christopher J"

Now showing 1 - 6 of 6
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    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.
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    Data for Boundary Frustration in Double-Gyroid Thin Films
    (2024-02-29) Magruder, Benjamin R; Morse, David C; Ellison, Christopher J; Dorfman, Kevin D; dorfman@umn.edu; Dorfman, Kevin D; Dorfman Group, UMN CEMS
    We have used self-consistent field theory to predict the morphology and preferred orientation of the double-gyroid phase in thin films of AB diblock polymers. A manuscript has been submitted containing this data, and is expected to appear shortly. The data were generated using the C++ version of the open-source software PSCF (https://pscf.cems.umn.edu/). All input and output files from PSCF used to generate the data in the paper are included in this dataset, as well as the code used to process the data and generate the figures.
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    Data for Surface Relief Terraces in Double Gyroid-Forming Polystyrene-block-Polylactide Thin Films
    (2023-09-28) Yang, Szu-Ming; Oh, Jinwoo; Magruder, Benjamin R; Kim, HeeJoong; Dorfman, Kevin D; Mahanthappa, Mahesh K; Ellison, Christopher J; cellison@umn.edu; Ellison, Christopher J; University of Minnesota Department of Chemical Engineering and Materials Science
    This study describes the thin film self-assembly behavior of a polystyrene-block-polylactide (SL-G) diblock copolymer, which undergoes melt self-assembly in bulk into a double gyroid (DG) network phase with a cubic unit cell parameter a = 52.7 nm. Scanning electron microscopy (SEM) and grazing-incidence small-angle X-ray scattering (GISAXS) reveal that thermally annealing 140–198 nm thick copolymer films on SiO2 substrates below the morphological order-to-disorder transition temperature yields polydomain DG structures, in which the (422) planes are oriented parallel to the surface. Bright-field optical microscopy (OM) and atomic force microscopy (AFM) analyses further reveal the film thickness-dependent formation of topographical terraces, including islands, holes, and bicontinuous features. The occurrence of these features sensitively depends on the incommensurability of the as-prepared film thickness and the (211)-interplanar spacing (d211) of the DG unit cell. While the steps heights between adjacent terraces exhibiting characteristic “double wave” patterns of the DG (422) planes coincide with d211, previously unreported transition zones between adjacent terraces are observed wherein “boomerang” and “droplet” patterns are observed. These intermediate patterns follow the expected sequence of adjacent termination planes of the bulk DG unit cell along the [211] direction, as confirmed by comparisons with self-consistent mean-field theory calculations.
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    Data for Thermodynamics and morphology of linear multiblock copolymers at homopolymer interfaces
    (2023-11-09) Collanton, Ryan P; Ellison, Christopher J; Dorfman, Kevin D; dorfman@umn.edu; Dorfman, Kevin D
    Block copolymers at homopolymer interfaces are poised to play a critical role in the compatibilization of mixed plastic waste, an area of growing importance as the rate of plastic accumulation rapidly increases. Using molecular dynamics simulations of Kremer–Grest polymer chains, we have investigated how the number of blocks and block degree of polymerization in a linear multiblock copolymer impacts the interface thermodynamics of strongly segregated homopolymer blends, which is key to effective compatibilization. The second virial coefficient reveals that interface thermodynamics are more sensitive to block degree of polymerization than to the number of blocks. Moreover, we identify a strong correlation between surface pressure (reduction of interfacial tension) and the spatial uniformity of block junctions on the interface, yielding a morphological framework for interpreting the role of compatibilizer architecture (number of blocks) and block degree of polymerization. These results imply that, especially at high interfacial loading, the choice of architecture of a linear multiblock copolymer compatibilizing surfactant does not greatly affect the modification of interfacial tension.
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    Data for Threading-the-Needle: Compatibilization of HDPE/iPP blends with butadiene-derived polyolefin block copolymers
    (2023-07-31) Shen, Liyang; Diaz Gorbea, Gabriela; Danielson, Evan; Cui, Shuquan; Ellison, Christopher J; Bates, Frank S; bates001@umn.edu; Bates, Frank S; University of Minnesota Department Chemical Engineering and Material Science
    Management of the plastic industry is a momentous challenge, one that pits enormous societal benefits against an accumulating reservoir of nearly indestructible waste. A promising strategy for recycling polyethylene (PE) and isotactic polypropylene (iPP), constituting roughly half the plastic produced annually worldwide, is melt blending for reformulation into useful products. Unfortunately, such blends are generally brittle and useless due to phase separation and mechanically weak domain interfaces. Recent studies have shown that addition of small amounts of semicrystalline PE-iPP block copolymers (ca. 1 wt%) to mixtures of these polyolefns results in ductility comparable to the pure materials. However, current methods for producing such additives rely on expensive reagents, prohibitively impacting the cost of recycling these inexpensive commodity plastics. Here, we describe an alternative strategy that exploits anionic polymerization of butadiene into block copolymers, with subsequent catalytic hydrogenation, yielding E and X blocks that are individually melt miscible with PE and iPP, where E and X are poly(ethylene-ran-ethylethylene) random copolymers with 6% and 90% ethylethylene repeat units, respectively. Cooling melt blended mixtures of PE and iPP containing 1 wt% of the triblock copolymer EXE of appropriate molecular weight, results in mechanical properties competitive with the component plastics. Blend toughness is obtained through interfacial topological entanglements of the amorphous X polymer and semicrystalline iPP, along with anchoring of the E blocks through cocrystallization with the PE homopolymer. Significantly, EXE can be inexpensively produced using currently practiced industrial scale polymerization methods, offering a practical approach to recycling the world’s top two plastics.
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    Supporting data for Surface Structure Dependent Circular Dichroism in Single and Double Gyroid Metamaterials
    (2022-06-16) William, Lenart R; Ellison, Christopher J; Ferry, Vivian E; Cote, Bryan M; veferry@umn.edu; Ferry, Vivian E.; Materials Research Science & Engineering Center
    Data includes the processed FDTD simulation results needed to recreate the figures in "Surface Structure Dependent Circular Dichroism in Single and Double Gyroid Metamaterials". The data files include single and double gyroids' reflection, transmission, and absorption spectra, near-field electric field intensity enhancements, and the gyroid 3D models used in the FDTD simulations.