Local dynamics in functionalized polymer grafted nanoparticle systems with weak and strong functional anisotropy

Area of Science:

• Soft Matter Physics
• Polymer Science
• Nanotechnology

Background:

• Polymer-grafted nanoparticles (PGNs) are crucial in advanced materials.
• Understanding their dynamic response to external forces is key for material design.
• Anisotropic interactions in PGNs are not fully understood, especially under shear.

Purpose of the Study:

• To investigate the impact of anisotropic interactions in end-functionalized PGNs on local dynamics.
• To analyze the rheological behavior of PGN systems under oscillatory shear deformation.
• To explore the role of functional anisotropy and oscillation frequency on system response.

Main Methods:

• Utilized a probability master equation approach to model bond evolution between PGNs.
• Simulated systems of three PGNs on a triangular lattice with varying bond energies.
• Applied controlled oscillatory shear deformation to study local dynamics.

Main Results:

• Functional anisotropy leads to broken symmetry in shear and normal forces relative to strain and strain rate.
• Anisotropic PGN systems exhibit distinct behaviors compared to isotropic systems, including elastic hysteresis and non-Maxwellian responses.
• Fourier analysis reveals strong dependence of local rheological features on functional anisotropy and the critical role of even harmonics.

Conclusions:

• Functional anisotropy in PGNs significantly dictates their dynamic rheological response under shear.
• The observed non-linear features are strongly linked to the degree of anisotropy and harmonic content.
• This study provides insights into designing advanced materials with tunable properties through controlled anisotropy.