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Research Highlight

Chain conformation of polymer melts with associating groups

Topics:
(Left) Snapshot of the molecular dynamics simulation box, with dimension L, and showing the associating beads (red) and the non-associating beads (blue). Kratky plots for (a) unmodified PB and PB-PTADs, based on the SANS measurements and (b) simulated associating polymer chains
(Left) Snapshot of the molecular dynamics simulation box, with dimension L, and showing the associating beads (red) and the non-associating beads (blue). Kratky plots for (a) unmodified PB and PB-PTADs, based on the SANS measurements and (b) simulated associating polymer chains

 

Achievement: Large-scale simulations and neutron scattering decode the role of inter- and intra-chain interactions in polymer melts.

Significance and Impact: Molecular associations in polymer melts are a root for viscoelastic properties and a full theoretical description can provide a means for improved design.

Research Details

  • Efficient large-scale molecular dynamics simulations provided the qualitative structural features of associating polymer melts and allowed exploring different strengths of association
  • Small angle neutron scattering (SANS) of monodisperse protonated and deuterated polybutadienes to experimental determine the melt structure
  • The effect of intrachain association is reflected by the change of radius of gyration, q dependence of scattering intensity, and the distribution of intrachain mean-square distance
  • Data shows a very important role of intrachain loops in associative polymer networks. 

Facility: This research (J.-M. Y. C. and Y. W.) was sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy. The polymer synthesis and characterization were carried out at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. This research used resources of the Leadership Computing Facility at Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC. W.-R. Chen and Z. Wang acknowledge the support by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials

Team: Jan-Michael Y. Carrillo, Wei-Ren Chen, Zhe Wang, Bobby G. Sumpter, Yangyang Wang

Sponsor: LDRD and BES - Scientific User Facilities Division

Citation and DOI: “Chain conformation of polymer melts with associating groups”, Jan-Michael Y. Carrillo1,2, Wei-Ren Chen3, Zhe Wang3, Bobby G. Sumpter1,2 and Yangyang Wang1, J. Phys. Commun. 3(22), 035007 (2019). DOI: 10.1088/2399-6528/ab09bb

1Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.

2Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.

2Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA.

3Neutron Scattering Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.

Summary: Using small-angle neutron scattering and large-scale molecular dynamics simulation, it was shown that while interchain association is important, intrachain association can’t be neglected in determining the static structures of associating polymers in the melt state. Careful analyses of the radius of gyration, static structure factor, and intrachain mean square distance of polymers with associating side groups revealed a substantial deviation from the random walk structure at even moderate association strength and degree of functionality. This finding emphasizes the important role of intrachain loops in associative polymer networks. Therefore, to fully understand the structure and dynamics of associating polymers, the presence of loops should be taken into consideration.