skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Small Particle Driven Chain Disentanglements in Polymer Nanocomposites

Abstract

Using neutron spin-echo spectroscopy, X-ray photon correlation spectroscopy and bulk rheology, we studied the effect of particle size on the single chain dynamics, particle mobility, and bulk viscosity in athermal polyethylene oxide-gold nanoparticle composites. The results reveal an ≈ 25 % increase in the reptation tube diameter with addition of nanoparticles smaller than the entanglement mesh size (≈ 5 nm), at a volume fraction of 20 %. The tube diameter remains unchanged in the composite with larger (20 nm) nanoparticles at the same loading. In both cases, the Rouse dynamics is insensitive to particle size. These results provide a direct experimental observation of particle size driven disentanglements that can cause non-Einstein-like viscosity trends often observed in polymer nanocomposites.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF); National Institute of Standards and Technology (NIST) - Center for Nanoscale Science and Technology (CNST)
OSTI Identifier:
1392526
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 118; Journal Issue: 14
Country of Publication:
United States
Language:
English

Citation Formats

Senses, Erkan, Ansar, Siyam M., Kitchens, Christopher L., Mao, Yimin, Narayanan, Suresh, Natarajan, Bharath, and Faraone, Antonio. Small Particle Driven Chain Disentanglements in Polymer Nanocomposites. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.118.147801.
Senses, Erkan, Ansar, Siyam M., Kitchens, Christopher L., Mao, Yimin, Narayanan, Suresh, Natarajan, Bharath, & Faraone, Antonio. Small Particle Driven Chain Disentanglements in Polymer Nanocomposites. United States. doi:10.1103/PhysRevLett.118.147801.
Senses, Erkan, Ansar, Siyam M., Kitchens, Christopher L., Mao, Yimin, Narayanan, Suresh, Natarajan, Bharath, and Faraone, Antonio. Sat . "Small Particle Driven Chain Disentanglements in Polymer Nanocomposites". United States. doi:10.1103/PhysRevLett.118.147801.
@article{osti_1392526,
title = {Small Particle Driven Chain Disentanglements in Polymer Nanocomposites},
author = {Senses, Erkan and Ansar, Siyam M. and Kitchens, Christopher L. and Mao, Yimin and Narayanan, Suresh and Natarajan, Bharath and Faraone, Antonio},
abstractNote = {Using neutron spin-echo spectroscopy, X-ray photon correlation spectroscopy and bulk rheology, we studied the effect of particle size on the single chain dynamics, particle mobility, and bulk viscosity in athermal polyethylene oxide-gold nanoparticle composites. The results reveal an ≈ 25 % increase in the reptation tube diameter with addition of nanoparticles smaller than the entanglement mesh size (≈ 5 nm), at a volume fraction of 20 %. The tube diameter remains unchanged in the composite with larger (20 nm) nanoparticles at the same loading. In both cases, the Rouse dynamics is insensitive to particle size. These results provide a direct experimental observation of particle size driven disentanglements that can cause non-Einstein-like viscosity trends often observed in polymer nanocomposites.},
doi = {10.1103/PhysRevLett.118.147801},
journal = {Physical Review Letters},
number = 14,
volume = 118,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}
  • Anomalous diffusion of polymer chains in a polymer nanocomposite melt is investigated for different polymer-nanoparticle interaction strengths using stochastic molecular dynamics simulations. For spherical nanoparticles dispersed in a polymer matrix the results indicate that the chain motion exhibits three distinct regions of diffusion, the Rouse-like motion, an intermediate subdiffusive regime followed by a normal Fickian diffusion. The motion of the chain end monomers shows a scaling that can be attributed to the formation of strong 'networklike' structures, which have been seen in a variety of polymer nanocomposite systems. Irrespective of the polymer-particle interaction strengths, these three regimes seem to bemore » present with small deviations. Further investigation on dynamic structure factor shows that the deviations simply exist due to the presence of strong enthalpic interactions between the monomers with the nanoparticles, albeit preserving the anomaly in the chain diffusion. The time-temperature superposition principle is also tested for this system and shows a striking resemblance with systems near glass transition and biological systems with molecular crowding. The universality class of the problem can be enormously important in understanding materials with strong affinity to form either a glass, a gel or networklike structures.« less
  • We investigate the interaction of the polymer matrix and filler in electrospun nanofibers using advanced thermal analysis methods. In particular, we study the ability of silicon dioxide nanoparticles to affect the phase structure of poly(ethylene terephthalate), PET. SiO{sub 2} nanoparticles (either unmodified or modified with silane) ranging from 0 to 2.0 wt% in PET were electrospun from hexafluoro-2-propanol solutions. The morphologies of both the electrospun (ES) nanofibers and the SiO{sub 2} powders were observed by scanning and transmission electron microscopy, while the amorphous or crystalline nature of the fibers was determined by real-time wide-angle X-ray scattering. The fractions of themore » crystal, mobile amorphous, and rigid amorphous phases of the non-woven, nanofibrous composite mats were quantified by using heat capacity measurements. The amount of the immobilized polymer layer, the rigid amorphous fraction, was obtained from the specific reversing heat capacity for both as-spun amorphous fibers and isothermally crystallized fibers. Existence of the rigid amorphous phase in the absence of crystallinity was verified in nanocomposite fibers, and two origins for confinement of the rigid amorphous fraction are proposed. Thermal analysis of electrospun fibers, including quasi-isothermal methods, provides new insights to quantitatively characterize the polymer matrix phase structure and thermal transitions, such as devitrification of the rigid amorphous fraction.« less