Effect of functional anisotropy on the local dynamics of polymer grafted nanoparticles

End-functionalised polymer grafted nanoparticles (PGNs) form bonds when their coronas overlap. The bonded interactions between the overlapping PGNs depend on the energy of the bonds ( U ). In the present study, oscillatory deformation imposed on a simple system with interacting PGNs placed on the ve...

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Bibliographic Details
Published in:Soft matter 2022-08, Vol.18 (33), p.629-6221
Main Author: Iyer, Balaji V. S
Format: Article
Language:English
Subjects:
Anisotropy
Apexes
Bonding
Broken symmetry
Coronas
Dynamic response
Field theory
Fourier analysis
Nanoparticles
Nonlinear response
Polymers
Self consistent fields
Shear thickening (liquids)
Stiffening
Thickening
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Summary:End-functionalised polymer grafted nanoparticles (PGNs) form bonds when their coronas overlap. The bonded interactions between the overlapping PGNs depend on the energy of the bonds ( U ). In the present study, oscillatory deformation imposed on a simple system with interacting PGNs placed on the vertices of a triangle is employed to examine the local dynamics as a function of energy of the bonds and the frequency of oscillation relative to the characteristic rupture frequency, ω 0 = 2π ν  exp(− U / k B T ), of the bonds. In particular, the effect of functional anisotropy is studied by introducing bonds of two different energies between adjacent PGNs. A multicomponent model developed by Kadre and Iyer, Macromol. Theory Simul. , 2021, 30 , 2100005, that combines the features of effective interactions between PGNs, self-consistent field theory and master equation approach to study bond kinetics is employed to obtain the local dynamics. The resulting force-strain curves are found to exhibit a simple broken symmetry where F x ( γ , &z.ggrda; ) ≠ − F x (− γ ,− &z.ggrda; ) and F y ( γ , &z.ggrda; ) ≠ F y (− γ ,− &z.ggrda; ) in systems with functional anisotropy. Fourier analysis of the dynamic response reveals that functional anisotropy leads to finite even harmonic terms and systematic variation of both the elastic and dissipative response from that of the isotropic systems. Furthermore, the intra-cycle variations in the strain stiffening and shear thickening ratios obtained from the analysis indicate that functional anisotropy leads to anisotropic nonlinear response. Dynamics depends on anisotropy introduced via energy of bonded interactions between end-functionalised polymer grafted nanoparticles (PGNs).
ISSN:1744-683X
1744-6848
DOI:10.1039/d2sm00710j