Dynamic Viscoelastic Properties of Confined Polymer Liquids Under Oscillatory Shear Flow

When liquids are confined in nanometer-scale gaps, they have characteristic viscoelastic properties that are greatly different from those of the liquids in the bulk state. In order to clarify the mechanism of this phenomenon, we have developed a new shear force measuring method. Our method can measure the viscoelasticity of the liquids that are confined and sheared in nanometer-scale gaps. By using the method, we investigated the gap dependence of the polymer liquid and found that both viscosity and elasticity increased drastically when the gap was decreased to a molecularly narrow width. In addition, we measured the shear rate dependence of the viscosity and found that the dependence to the shear rate increased as a result of the confinement.