Synthesis of small molar mass perdeuterated polyethylpropylene (d-PEP) as an auxiliary for neutron studies |
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Authors: | Frederik C. Krebs Mikkel Jørgensen Bente Lebech Kristoffer Almdal Walther B. Pedersen |
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Affiliation: | Condensed Matter Physics and Chemistry Department, Macromolecular Chemistry, Ris? National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark, DK
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Abstract: | Summary An inert non-crystalline cryoprotectant oil was needed as a non-incoherent scattering matrix for neutron studies of solvent containing crystalline materials. This led us to prepare perdeuterated polyethylpropylene (PEP) with a molar mass around 1100 g/mol. On route to this material an improved method for the preparation of isoprene-d8 starting from calcium carbide and acetone-d6 was devised. Subsequent anionic polymerization using t-butyl lithium as initiator resulted in an oligomeric perdeuterated polyisoprene (PI) with an average chain length of approx. 15 monomer units and Mw/Mn: 1.1. This polymer was deuterated with D2 and Pd/C (10%) in cyclohexane to yield the desired perdeutero polymer (PEP-d). The polymer fulfill the important properties that it does not crystallize at low temperature and has a low neutron scattering efficiency. Received: 15 September 1999/Revised version: 3 November 1999/Accepted: 3 November 1999 |
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