TY - JOUR
T1 - Effect of Polymer Chemistry on Chain Conformations in Hairy Nanoparticle Assemblies
AU - Hansoge, Nitin K.
AU - Keten, Sinan
N1 - Funding Information:
S.K. and N.H. acknowledge support from an ONR Director of Research Early Career Award (PECASE, Award #N00014163175). This work is also supported by the Center for Hierarchical Materials Design (CHiMaD) that is funded by the National Institute of Standards and Technology (NIST; Award #70NANB14H012). The authors acknowledge support from the Department of Mechanical Engineering at Northwestern University and a supercomputing grant from the Northwestern University High Performance Computing Center, as well as the Department of Defense Supercomputing Resource Center.*%blankline%**%blankline%*
Funding Information:
S.K. and N.H. acknowledge support from an ONR Director of Research Early Career Award (PECASE, Award #N00014163175). This work is also supported by the Center for Hierarchical Materials Design (CHiMaD) that is funded by the National Institute of Standards and Technology (NIST; Award #70NANB14H012). The authors acknowledge support from the Department of Mechanical Engineering at Northwestern University and a supercomputing grant from the Northwestern University High Performance Computing Center, as well as the Department of Defense Supercomputing Resource Center.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/10/15
Y1 - 2019/10/15
N2 - Matrix-free, polymer-grafted nanoparticles, called hairy nanoparticle assemblies (aHNPs), have proven advantageous over traditional nanocomposites, as good dispersion and structural order can be achieved. Recent studies have shown that conformational changes in the polymer structure can lead to significant enhancements in the mechanical properties of aHNPs. To quantify how polymer chemistry affects the chain conformations in aHNPs, here we present a comparative analysis based on coarse-grained molecular dynamics simulations. Specifically, we compare the chain conformations in an anisotropic cellulose nanoparticle grafted to four common polymers with distinct chemical groups, fragility, and segmental structures, that is, poly(methyl methacrylate) (PMMA), polystyrene (PS), polycarbonate (PC), and polybutadiene (PB). We observe that semiflexible glassy polymers such as PMMA and PS have a higher critical chain length (Ncr), the transition point where the polymer conformation changes from concentrated to semidilute brush regime. Flexible rubbery polymers (PB) can overcome the Ncr barrier at relatively lower molecular weights. We have used theoretical scaling laws based on Daoud-Cotton theory to uncover a direct correlation between empirical constants and physical parameters, such as persistence length and monomer excluded volume. Furthermore, we carried out a systematic study to understand the role of backbone rigidity and side-group size of polymer, and it revealed that the backbone rigidity significantly affects Ncr but the side-group size doesn't seem to have an appreciable effect on Ncr. We find that normalization of the monomer radial distribution curves using Ncr and other key molecular parameters collapses the curves for 110 distinct model aHNP systems studied. Our work paves the way for systematic quantification of these molecular design parameters to accelerate the design of polymer-grafted nanoparticle assemblies in combination with universal scaling relationships.
AB - Matrix-free, polymer-grafted nanoparticles, called hairy nanoparticle assemblies (aHNPs), have proven advantageous over traditional nanocomposites, as good dispersion and structural order can be achieved. Recent studies have shown that conformational changes in the polymer structure can lead to significant enhancements in the mechanical properties of aHNPs. To quantify how polymer chemistry affects the chain conformations in aHNPs, here we present a comparative analysis based on coarse-grained molecular dynamics simulations. Specifically, we compare the chain conformations in an anisotropic cellulose nanoparticle grafted to four common polymers with distinct chemical groups, fragility, and segmental structures, that is, poly(methyl methacrylate) (PMMA), polystyrene (PS), polycarbonate (PC), and polybutadiene (PB). We observe that semiflexible glassy polymers such as PMMA and PS have a higher critical chain length (Ncr), the transition point where the polymer conformation changes from concentrated to semidilute brush regime. Flexible rubbery polymers (PB) can overcome the Ncr barrier at relatively lower molecular weights. We have used theoretical scaling laws based on Daoud-Cotton theory to uncover a direct correlation between empirical constants and physical parameters, such as persistence length and monomer excluded volume. Furthermore, we carried out a systematic study to understand the role of backbone rigidity and side-group size of polymer, and it revealed that the backbone rigidity significantly affects Ncr but the side-group size doesn't seem to have an appreciable effect on Ncr. We find that normalization of the monomer radial distribution curves using Ncr and other key molecular parameters collapses the curves for 110 distinct model aHNP systems studied. Our work paves the way for systematic quantification of these molecular design parameters to accelerate the design of polymer-grafted nanoparticle assemblies in combination with universal scaling relationships.
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U2 - 10.1021/acsmacrolett.9b00526
DO - 10.1021/acsmacrolett.9b00526
M3 - Article
C2 - 35651164
AN - SCOPUS:85073713110
SN - 2161-1653
VL - 8
SP - 1209
EP - 1215
JO - ACS Macro Letters
JF - ACS Macro Letters
IS - 10
ER -