Browsing by Author "Hillmyer Group"

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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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    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.