Polymer Topology Effects on Dynamics of Comb Polymer Melts

Journal Article · 20 September 2018 · Macromolecules

DOI: https://doi.org/10.1021/acs.macromol.8b01449 · OSTI ID:1474056

Wijesinghe, Sidath ^[1]; Perahia, Dvora  ^[1]; Grest, Gary S.  ^[2]

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1. Clemson Univ., SC (United States). Dept. of Chemistry
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Controlling polymer viscosity and flow is key to their many applications through strength and processability. The topology of the polymer i.e., linear, stars, and branched, affects the macroscopic flow characteristics of melts, where introducing one branch is sufficient to increase the viscosity significantly. While a number of studies have probed the effects of polymer topology on their rheology, the molecular understanding that underlies the macroscopic behavior remains an open question. The current study uses molecular dynamics simulations to resolve the effects of topology of polymer melts on chain mobility and viscosity in the comb regime using polyethylene as a model system. A coarse-grained model where four methylene groups constitute one bead is used, and the results are transposed to the atomistic level. Here, we find that while the number of branches only slightly affects the chain mobility and viscosity, their length strongly impacts their behavior. Finally, the results are discussed in terms of interplay between the relaxation of the branches and reptation of the backbone where the topology of the polymer affects the tube dimensions.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000; NA0003525
• OSTI ID: 1474056
• Alternate ID(s): OSTI ID: 1477311
• Report Number(s): SAND-2018-10129J; SAND2018-10461J; 667902
• Journal Information: Macromolecules, Vol. 51, Issue 19; ISSN 0024-9297
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English