811794-45-3Relevant articles and documents
Decreasing the alkyl branch frequency in precision polyethylene: Pushing the limits toward longer run lengths
Inci, Bora,Wagener, Kenneth B.
, p. 11872 - 11875 (2011)
A symmetrical α,ω-diene monomer with a 36 methylene run length was synthesized and polymerized, and the unsaturated polymer was hydrogenated to generate precision polyethylene possessing a butyl branch on every 75th carbon (74 methylenes between branch points). The precision polymer sharply melts at 104 °C and exhibits the typical orthorhombic unit cell structure with two characteristic wide-angle X-ray diffraction (WAXD) crystalline peaks observed at 21.5° and 24.0°, corresponding to reflection planes (110) and (200), respectively.
On-Nanoparticle Gating Units Render an Ordinary Catalyst Substrate- And Site-Selective
Kim, Minju,Dygas, Miroslaw,Sobolev, Yaroslav I.,Beker, Wiktor,Zhuang, Qiang,Klucznik, Tomasz,Ahumada, Guillermo,Ahumada, Juan Carlos,Grzybowski, Bartosz A.
supporting information, p. 1807 - 1815 (2021/02/05)
When an organometallic catalyst is tethered onto a nanoparticle and is embedded in a monolayer of longer ligands terminated in "gating"end-groups, these groups can control the access and orientation of the incoming substrates. In this way, a nonspecific catalyst can become enzyme-like: it can select only certain substrates from substrate mixtures and, quite remarkably, can also preorganize these substrates such that only some of their otherwise equivalent sites react. For a simple, copper-based click reaction catalyst and for gating ligands terminated in charged groups, both substrate- and site-selectivities are on the order of 100, which is all the more notable given the relative simplicity of the on-particle monolayers compared to the intricacy of enzymes' active sites. The strategy of self-assembling macromolecular, on-nanoparticle environments to enhance selectivities of "ordinary"catalysts presented here is extendable to other types of catalysts and gating based on electrostatics, hydrophobicity, and chirality, or the combinations of these effects. Rational design of such systems should be guided by theoretical models we also describe.
Decreasing the alkyl branch frequency in precision polyethylene: Effect of alkyl branch size on nanoscale morphology
Inci, Bora,Lieberwirth, Ingo,Steffen, Werner,Mezger, Markus,Graf, Robert,Landfester, Katharina,Wagener, Kenneth B.
scheme or table, p. 3367 - 3376 (2012/07/28)
Synthesis and morphological characterization are reported for a series of 13 precision branched polyethylene structures, the branch being placed on every 39th carbon and varying in size from methyl to pentadecyl group. A recently established synthetic scheme for preparation of the symmetrical α,ω-diene monomer was employed to increase the number of methylene carbons between the branch points from 20 to 38, yielding polymers with 5.26 mol % α-olefin incorporation. The morphology of these polymers was investigated using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM). Methyl branching significantly reduces the melting point and single crystal lamellae thickness of unbranched polyethylene. On the other hand, all further branches from ethyl to pentadecyl produce polymers that have similar melting points and single crystal lamellae thicknesses. A clear change in the morphology of both solution and melt-grown crystals of these polymers was observed from a situation where the methyl branch is incorporated in the polymer's unit cell to one where branches of greater mass are mostly expelled from the unit cell.
