title: Molecular Dynamics in the Crystalline Regions of Poly(ethylene oxide) Containing a Well-Defined Point Defect in the Middle of the Polymer Chain.
abstract: The chain mobility in crystals of a homopolymer of poly(ethylene oxide) (PEO) with 22 monomer units (PEO22) is compared with that of a PEO having the identical number of monomer units but additionally a 1,4-disubstituted 1,2,3-triazole (TR) point defect in the middle of the chain (PEO11-TR-PEO11). In crystals of PEO22, the characteristic αc-relaxation (helix jumps) is detected and the activation energy of this process is calculated from the pure crystalline1H FIDs to 67 kJ/mol. PEO11-TR-PEO11exhibits a more complex behavior, i.e. a transition into the high temperature phase HTPh is noticed during heating in the temperature range between -5 and 10 °C which is attributed to the incorporation of the TR ring into the crystalline lamellae. The crystal mobility of the low temperature phase LTPh of PEO11-TR-PEO11is in good agreement with PEO22since helical jump motions could also be detected by analysis of the1H FIDs and the corresponding values of their second moments M2. In contrast, the high temperature phase of PEO11-TR-PEO11shows a completely different behavior of the crystal mobility. The crystalline PEO chains are rigid in this HTPh on the time scale of both, the1H time-domain technique and in13C MAS CODEX NMR spectroscopy, i.e. the αc-mobility of PEO in the HTPh of PEO11-TR-PEO11is completely suppressed and the PEO11chains are converted into a crystal-fixed polymer due to the incorporation of the TR rings into the crystal structure. However, the TR defect of PEO11-TR-PEO11shows in the HTPh characteristic π-flip motions with an Arrhenius type activation energy of 223 kJ/mol measured by dielectric relaxation spectroscopy. This motion cannot be observed by corresponding13C MAS CODEX NMR measurements due to an interfering spin-dynamic effect.
authors.affiliation: Faculty of Natural Sciences II, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany.
authors.forename: Yury
authors.initials: Y
authors.lastname: Golitsyn
authors.affiliation: Faculty of Natural Sciences II, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany.
authors.forename: Martin
authors.identifier: 0000-0001-5957-9895
authors.initials: M
authors.lastname: Pulst
authors.affiliation: Faculty of Natural Sciences II, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany.
authors.forename: Jörg
authors.identifier: 0000-0001-8571-5985
authors.initials: J
authors.lastname: Kressler
authors.affiliation: Faculty of Natural Sciences II, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany.
authors.forename: Detlef
authors.identifier: 0000-0002-6876-1901
authors.initials: D
authors.lastname: Reichert