Kinetic Polymer Arrest in Percolated SWNT Networks

Published

December 3, 2014

Author(s)

Rana NMN Ashkar, Mansour Abdul Baki, Madhu Sudan Tyagi, Antonio Faraone, Paul Butler, Ramanan Krishnamoorti

Abstract

The inclusion of single-wall carbon nanotubes (SWNT) in a polymer, with interchain distances comparable to the SWNT diameter, can significantly perturb the structural and dynamical properties of interfacial polymeric units. For SWNT concentrations above the percolation threshold, the interfacial regions start to overlap rendering a complex dynamical response that is not readily predictable. In this work, we use neutron scattering as a direct probe of local polymer dynamics in PMMA composites with percolated SWNT networks. Backscattering data show a monotonous decrease in the fraction of mobile polymer with increasing SWNT loading, along with a significant suppression of the mean-square displacements (MSD) in the composites relative to pristine PMMA. Surprisingly, only slight differences in the MSDs are noted with different loadings. These observations suggest that, once percolated, the nanotubes induce connectedness in the adjacent slow polymer domains, which consequently impose dynamical constraints on the otherwise-fast bulk domains. Supporting NSE measurements of the chain relaxations reveal an order of magnitude slowdown in the composites compared to PMMA.

Citation

ACS Macro Letters

Volume

3

Pub Type

Journals

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Keywords

Carbon nanocomposites, segmental dynamics, polymer mobility, dynamic caging, SWNT, PMMA

Citation

, R. , , M. , , M. , Faraone, A. , Butler, P. and Krishnamoorti, R. (2014), Kinetic Polymer Arrest in Percolated SWNT Networks, ACS Macro Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=916205 (Accessed July 17, 2024)