TiO₂-modified Carbon Nanoparticles (CNPs@TiO₂) Enabled Interfacial Charge Regulation.

Area of Science:

• Materials Science
• Nanotechnology
• Rheology

Background:

• Carbon-based electrorheological (ER) fluids face challenges balancing polarization strength with electrical stability.
• High electronic mobility in these fluids can cause leakage current and voltage collapse under strong electric fields.
• A critical need exists for ER fluids that maintain performance without electrical degradation.

Purpose of the Study:

• To design and synthesize novel carbon nanoparticles modified with titanium dioxide (TiO2) for improved ER fluid performance.
• To decouple polarization efficiency from conductive percolation in carbon-based ER fluids.
• To achieve stable ER fluid operation at high electric fields and low nanoparticle loadings.

Main Methods:

• Synthesis of TiO2-surface-modified carbon nanoparticles (CNPs@TiO2).
• Characterization using structural and chemical analyses (e.g., EIS, leakage-current measurements).
• Evaluation of ER fluid performance in low-viscosity silicone oil, including viscosity enhancement, yield stress, dynamic switching, and stability tests.
• Density functional theory (DFT) calculations to understand interfacial charge behavior.

Main Results:

• CNPs@TiO2 exhibited strong intrinsic polarizability with limited charge transport due to amorphous TiO2.
• The ER fluids demonstrated stable operation up to 3000 V with microampere-level leakage current and no voltage collapse.
• At 3 wt % loading, a significant viscosity enhancement of ~1870% and yield stress of 25.5 Pa were achieved with fast response times.
• Comparison with TiO2-only controls confirmed the synergistic effect of the CNP-TiO2 heterointerface.

Conclusions:

• Interfacial charge regulation via TiO2 surface modification is an effective strategy for developing stable, low-loading ER fluids.
• The CNPs@TiO2 system overcomes the trade-off between polarization and electrical stability in carbon-based ER fluids.
• This approach offers a scalable pathway towards energy-efficient adaptive fluid systems with low baseline viscosity.