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Title: Structure and component dynamics in binary mixtures of poly(2-(dimethylamino)ethyl methacrylate) with water and tetrahydrofuran: A diffraction, calorimetric, and dielectric spectroscopy study

Abstract

We have combined X-ray diffraction, neutron diffraction with polarization analysis, small angle neutron scattering, differential scanning calorimetry, and broad band dielectric spectroscopy to investigate the structure and dynamics of binary mixtures of poly (2-(dimethylamino)ethyl methacrylate) with either water or tetrahydrofuran (THF) at different concentrations. Aqueous mixtures are characterized by a highly heterogeneous structure where water clusters coexist with an underlying nano-segregation of main chains and side groups of the polymeric matrix. THF molecules are homogeneously distributed among the polymeric nano-domains for concentrations of one THF molecule/monomer or lower. A more heterogeneous situation is found for higher THF amounts, but without evidences for solvent clusters. In THF-mixtures, we observe a remarkable reduction of the glass-transition temperature which is enhanced with increasing amount of solvent but seems to reach saturation at high THF concentrations. Adding THF markedly reduces the activation energy of the polymer β-relaxation. The presence of THF molecules seemingly hinders a slow component of this process which is active in the dry state. The aqueous mixtures present a strikingly broad glass-transition feature, revealing a highly heterogeneous behavior in agreement with the structural study. Regarding the solvent dynamics, deep in the glassy state all data can be described by an Arrheniusmore » temperature dependence with a rather similar activation energy. However, the values of the characteristic times are about three orders of magnitude smaller for THF than for water. Water dynamics display a crossover toward increasingly higher apparent activation energies in the region of the onset of the glass transition, supporting its interpretation as a consequence of the freezing of the structural relaxation of the surrounding matrix. The absence of such a crossover (at least in the wide dynamic window here accessed) in THF is attributed to the lack of cooperativity effects in the relaxation of these molecules within the polymeric matrix.« less

Authors:
 [1];  [1];  [2];  [3];  [1]
  1. Centro de Física de Materiales (CFM) (CSIC–UPV/EHU)—Materials Physics Center - MPC, Paseo Manuel de Lardizabal 5, 20018 San Sebastián (Spain)
  2. Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85747 Garching (Germany)
  3. Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen (Switzerland)
Publication Date:
OSTI Identifier:
22660698
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 144; Journal Issue: 15; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACTIVATION ENERGY; BINARY MIXTURES; CALORIMETRY; CONCENTRATION RATIO; DIELECTRIC MATERIALS; METHACRYLATES; NEUTRON DIFFRACTION; POLYMERIZATION; POLYMERS; SOLVENTS; SPECTROSCOPY; TEMPERATURE DEPENDENCE; TETRAHYDROFURAN; X-RAY DIFFRACTION

Citation Formats

Goracci, G., E-mail: sckgorag@ehu.es, Arbe, A., Alegría, A., Departamento de Física de Materiales, Su, Y., Gasser, U., Colmenero, J., Departamento de Física de Materiales, and Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián. Structure and component dynamics in binary mixtures of poly(2-(dimethylamino)ethyl methacrylate) with water and tetrahydrofuran: A diffraction, calorimetric, and dielectric spectroscopy study. United States: N. p., 2016. Web. doi:10.1063/1.4946004.
Goracci, G., E-mail: sckgorag@ehu.es, Arbe, A., Alegría, A., Departamento de Física de Materiales, Su, Y., Gasser, U., Colmenero, J., Departamento de Física de Materiales, & Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián. Structure and component dynamics in binary mixtures of poly(2-(dimethylamino)ethyl methacrylate) with water and tetrahydrofuran: A diffraction, calorimetric, and dielectric spectroscopy study. United States. https://doi.org/10.1063/1.4946004
Goracci, G., E-mail: sckgorag@ehu.es, Arbe, A., Alegría, A., Departamento de Física de Materiales, Su, Y., Gasser, U., Colmenero, J., Departamento de Física de Materiales, and Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián. 2016. "Structure and component dynamics in binary mixtures of poly(2-(dimethylamino)ethyl methacrylate) with water and tetrahydrofuran: A diffraction, calorimetric, and dielectric spectroscopy study". United States. https://doi.org/10.1063/1.4946004.
@article{osti_22660698,
title = {Structure and component dynamics in binary mixtures of poly(2-(dimethylamino)ethyl methacrylate) with water and tetrahydrofuran: A diffraction, calorimetric, and dielectric spectroscopy study},
author = {Goracci, G., E-mail: sckgorag@ehu.es and Arbe, A. and Alegría, A. and Departamento de Física de Materiales and Su, Y. and Gasser, U. and Colmenero, J. and Departamento de Física de Materiales and Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián},
abstractNote = {We have combined X-ray diffraction, neutron diffraction with polarization analysis, small angle neutron scattering, differential scanning calorimetry, and broad band dielectric spectroscopy to investigate the structure and dynamics of binary mixtures of poly (2-(dimethylamino)ethyl methacrylate) with either water or tetrahydrofuran (THF) at different concentrations. Aqueous mixtures are characterized by a highly heterogeneous structure where water clusters coexist with an underlying nano-segregation of main chains and side groups of the polymeric matrix. THF molecules are homogeneously distributed among the polymeric nano-domains for concentrations of one THF molecule/monomer or lower. A more heterogeneous situation is found for higher THF amounts, but without evidences for solvent clusters. In THF-mixtures, we observe a remarkable reduction of the glass-transition temperature which is enhanced with increasing amount of solvent but seems to reach saturation at high THF concentrations. Adding THF markedly reduces the activation energy of the polymer β-relaxation. The presence of THF molecules seemingly hinders a slow component of this process which is active in the dry state. The aqueous mixtures present a strikingly broad glass-transition feature, revealing a highly heterogeneous behavior in agreement with the structural study. Regarding the solvent dynamics, deep in the glassy state all data can be described by an Arrhenius temperature dependence with a rather similar activation energy. However, the values of the characteristic times are about three orders of magnitude smaller for THF than for water. Water dynamics display a crossover toward increasingly higher apparent activation energies in the region of the onset of the glass transition, supporting its interpretation as a consequence of the freezing of the structural relaxation of the surrounding matrix. The absence of such a crossover (at least in the wide dynamic window here accessed) in THF is attributed to the lack of cooperativity effects in the relaxation of these molecules within the polymeric matrix.},
doi = {10.1063/1.4946004},
url = {https://www.osti.gov/biblio/22660698}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 15,
volume = 144,
place = {United States},
year = {Thu Apr 21 00:00:00 EDT 2016},
month = {Thu Apr 21 00:00:00 EDT 2016}
}