Synthesis and Crystallization of Precision Polymers with Repetitive Folding Elements
2014; Wiley; Volume: 215; Issue: 20 Linguagem: Inglês
10.1002/macp.201400183
ISSN1521-3935
AutoresSophie Reimann, Ute Baumeister, Wolfgang H. Binder,
Tópico(s)Organometallic Complex Synthesis and Catalysis
ResumoThe synthesis and thermal properties of a new type of precision polyethylene containing perfectly placed conformationally constraining elements after every 16 methylene units are presented. The precise placement of a 2,6‐diaminopyridine moiety (DAP) is accomplished via acyclic diene metathesis (ADMET) polymerization of specially designed monomers, where the DAP serves as the conformational constraint. Polymerization of the diene‐monomer ( N,N′ ‐pyridin‐2,6‐diyl‐bis‐dec‐9‐enamide) displaying free‐amide hydrogen bonds leads to largely insoluble polymers due to self‐aggregation via the hydrogen bonds and π–π stacking. However, when using the N ‐methyl‐protected monomer N,N ′‐pyridin‐2,6‐diylbis( N ‐methyldec‐9‐enamide), the polymerization furnishes soluble polymers with molecular weights ranging from 1500 up to 60 000 g mol −1 using different Grubbs or Umicore catalysts. Matrix‐assisted laser desorption/ionization (MALDI) measurements prove the structure of linear and cyclic polymers, all containing the precisely placed DAP units within the polymer. Subsequent hydrogenation with p ‐toluenesulfonhydrazide yields the final semicrystalline polymers, displaying an ordered lamellar crystal phase as characterized via differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) measurements. image
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