Browsing by Subject "ring-opening metathesis polymerization"

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    Supporting data for Core−Shell Gyroid in ABC Bottlebrush Block Terpolymers
    (2023-05-25) Cui, Shuquan; Zhang, Bo; Shen, Liyang; Bates, Frank S; Lodge, Timothy P; lodge@umn.edu; Lodge, Timothy P; University of Minnesota Department of Chemistry
    These files contain primary data supporting all results reported in Cui et al. "Core−shell gyroid in ABC bottlebrush block terpolymers." A series of bottlebrush block polymers containing 24 PEP-PS diblock copolymers and 109 PEP-PS-PEO triblock terpolymers were synthesized by ring-opening metathesis polymerization (ROMP) of norbornene-functionalized poly(ethylene-alt-propylene) (PEP), poly(styrene) (PS), and poly(ethylene oxide) (PEO) macromonomers. The molecular weights of the three macromonomers were around 1 kg/mol. The relatively modest total backbone degrees of polymerization ranged from ca. 20 to 40. Morphologies of these bottlebrush block polymers were characterized by small-angle X-ray scattering (SAXS). The PEP-PS diblocks exhibited only cylindrical (HEX) and lamellar (LAM) morphologies; the desired network phases did not appear in these materials, consistent with previous experimental studies. However, adding variable-length bottlebrush PEO blocks to diblocks containing 30% to 50% PS led to a substantial core-shell double gyroid (GYR) phase window in the ternary phase portrait. Encouragingly, the GYR unit cell dimensions increased almost linearly with the backbone degree of polymerization, portending the ability to access larger network dimensions than previously obtained with linear block polymers. This finding demonstrates a periodic network phase in bottlebrush block polymers for the first time and highlights extraordinary opportunities associated with applying facile ROMP chemistry to multiblock bottlebrush polymers.
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    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.
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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.