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Title: Distribution of Chains in Polymer Brushes Produced by a “Grafting From” Mechanism

The molecular weight and polydispersity of the chains in a polymer brush are critical parameters determining the brush properties. However, the characterization of polymer brushes is hindered by the vanishingly small mass of polymer present in brush layers. In this study, in order to obtain sufficient quantities of polymer for analysis, polymer brushes were grown from high surface area fibrous nylon membranes by ATRP. We synthesized the brushes with varying surface initiator densities, polymerization times, and amounts of sacrificial initiator, then cleaved from the substrate, and analyzed by GPC and NMR. Characterization showed that the surface-grown polymer chains were more polydisperse and had lower average molecular weight compared to solution-grown polymers synthesized concurrently. Furthermore, the molecular weight distribution of the polymer brushes was observed to be bimodal, with a low molecular weight population of chains representing a significant mass fraction of the polymer chains at high surface initiator densities. Moreover, the origin of this low MW polymer fraction is proposed to be the termination of growing chains by recombination during the early stages of polymerization, a mechanism confirmed by molecular dynamics simulations of brush polymerization.
 [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of Connecticut, Storrs, CT (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of Akron, OH (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; CHE-1310453; DMR-1004576
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 49; Journal Issue: 2; Journal ID: ISSN 0024-9297
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
Sponsoring Org:
USDOE; National Science Foundation (NSF)
Country of Publication:
United States
OSTI Identifier: