Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations

Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations

Bibliographic Details
Main Author: Trazkovich, Alex
Language:English
Published: The Ohio State University / OhioLINK 2019
Subjects:
Chemical Engineering
copolymer sequence
block copolymer
polymer nanocomposite
dynamic modulus
relaxation times
interphase properties
interphase dynamics
molecular dynamics
local dynamic modulus
tire mechanics
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=osu1545930453011375
id ndltd-OhioLink-oai-etd.ohiolink.edu-osu1545930453011375
record_format oai_dc
collection NDLTD
language English
sources NDLTD
topic Chemical Engineering
copolymer sequence
block copolymer
polymer nanocomposite
dynamic modulus
relaxation times
interphase properties
interphase dynamics
molecular dynamics
local dynamic modulus
tire mechanics
spellingShingle Chemical Engineering
copolymer sequence
block copolymer
polymer nanocomposite
dynamic modulus
relaxation times
interphase properties
interphase dynamics
molecular dynamics
local dynamic modulus
tire mechanics
Trazkovich, Alex
Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations
author Trazkovich, Alex
author_facet Trazkovich, Alex
author_sort Trazkovich, Alex
title Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations
title_short Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations
title_full Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations
title_fullStr Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations
title_full_unstemmed Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations
title_sort effect of copolymer sequence on mechanical properties of polymer nanocomposites from molecular dynamics simulations
publisher The Ohio State University / OhioLINK
publishDate 2019
url http://rave.ohiolink.edu/etdc/view?acc_num=osu1545930453011375
work_keys_str_mv AT trazkovichalex effectofcopolymersequenceonmechanicalpropertiesofpolymernanocompositesfrommoleculardynamicssimulations
_version_ 1719454945670856704
spelling ndltd-OhioLink-oai-etd.ohiolink.edu-osu15459304530113752021-08-03T07:09:26Z Effect of Copolymer Sequence on Mechanical Properties of Polymer Nanocomposites from Molecular Dynamics Simulations Trazkovich, Alex Chemical Engineering copolymer sequence block copolymer polymer nanocomposite dynamic modulus relaxation times interphase properties interphase dynamics molecular dynamics local dynamic modulus tire mechanics When incorporated into polymers, nanoparticles are known to modify the structure and dynamics of nearby polymer chains. Because nanoparticles have a high surface area to volume ratio, the properties of the polymer-nanoparticle interphase region can have a significant effect on the overall composite properties even at relatively low nanoparticle loading. In this work, we study the polymer-nanoparticle interphase region using molecular dynamics simulations, and we analyze the impact of a nanoparticle on local structure, dynamics, and viscoelastic properties.Of particular interest here is a class of systems which consists of nanoparticles incorporated into two-component copolymers where one component of the copolymer interacts more favorably with the nanoparticle than the other. In these systems, modifying the particular copolymer sequence may modify the interphase properties, and composite properties may therefore be adjusted even while maintaining the same overall monomer ratio. These systems have been the subject of several simulation studies focused on nanoparticle dispersion and assembly; however, relatively little simulation work has focused specifically on the impact of copolymer sequence on properties of the copolymer-nanoparticle interphase. We simulate a simple nanocomposite consisting of a single spherical nanoparticle surrounded by coarse-grained polymer chains. The polymers are composed of two different monomer types that differ only in their interaction strengths with the nanoparticle. By studying a series of regular multiblock copolymers with adjustable block length as well as a random copolymer, we examine the effect of copolymer sequence blockiness on the structure as well as the end-to-end vector autocorrelation, bond vector autocorrelation, and self-intermediate scattering function relaxation times as a function of distance from the nanoparticle surface. We find that, depending on block length, blocky copolymers can have faster or slower interphase dynamics than a random copolymer. Certain blocky copolymer sequences also lead to relaxation times near the nanoparticle surface that are slower than those of homopolymer systems composed of either component monomer. To analyze viscoelastic mechanical properties in the interphase, we measure local atomic stress fluctuations and use them to estimate the local stress autocorrelation as a function of distance from the nanoparticle. This local stress autocorrelation is then used to estimate the local dynamic modulus. This allows us to examine the effect of adjusting copolymer sequence on the dynamic modulus as a function of both frequency of excitation and distance from the nanoparticle. Notably, we find that certain copolymer sequences can lead to a higher viscoelastic hysteresis in the interphase than either homopolymer system, suggesting that tuning copolymer sequence could allow for significant control over nanocomposite dynamics.To demonstrate a possible application of adjusting material properties using copolymer sequence, we briefly consider a design challenge motivated by tire tread compounds, in which improving traction without sacrificing fuel economy requires increasing high-frequency hysteresis while maintaining low-frequency hysteresis. By considering an additional set of sequences motivated by our results from studying regular multiblock copolymers, we show how further adjusting copolymer sequence can be used to make progress toward this goal. 2019-07-08 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1545930453011375 http://rave.ohiolink.edu/etdc/view?acc_num=osu1545930453011375 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

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