Revisiting the crystallization of poly(2‐alkyl‐2‐oxazoline)s |
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| Authors: | A Levent Demirel P?nar Tatar Güner Bart Verbraeken Helmut Schlaad Ulrich S Schubert Richard Hoogenboom |
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| Institution: | 1. Chemistry Department, Ko? University, Sariyer, Istanbul, Turkey;2. Supramolecular Chemistry Group, Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium;3. University of Potsdam, Institute of Chemistry, Potsdam, Germany;4. Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, Eindhoven, Netherlands;5. Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena and Jena Center for Soft Matter (JCSM), Jena, Germany |
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| Abstract: | Poly(2‐alkyl‐2‐oxazoline)s (PAOx) exhibit different crystallization behavior depending on the length of the alkyl side chain. PAOx having methyl, ethyl, or propyl side chains do not show any bulk crystallization. Crystallization in the heating cycle, that is, cold crystallization, is observed for PAOx with butyl and pentyl side chains. For PAOx with longer alkyl side chains crystallization occurs in the cooling cycle. The different crystallization behavior is attributed to the different polymer chain mobility in line with the glass transition temperature (Tg) dependency on alkyl side chain length. The decrease in chain mobility with decreasing alkyl side chain length hinders the relaxation of the polymer backbone to the thermodynamic equilibrium crystalline structure. Double melting behavior is observed for PButOx and PiPropOx which is explained by the melt‐recrystallization mechanism. Isothermal crystallization experiments of PButOx between 60 and 90 °C and PiPropOx between 90 and 150 °C show that PAOx can crystallize in bulk when enough time is given. The decrease of Tg and the corresponding increase in chain mobility at T > Tg with increasing alkyl side chain length can be attributed to an increasing distance between the polymer backbones and thus decreasing average strength of amide dipole interactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 721–729 |
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| Keywords: | chain mobility crystallization differential scanning calorimetry (DSC) effect of alkyl side chains glass transition temperature melt melt‐recrystallization polymer crystallization |
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