Determination of Elastic Modulus of Composite PS/CeO2 Core-shell Microspheres by Atomic Force Microscope
核壳结构PS/CeO2复合微球弹性模量的AFM测定

Atomic force microscopy (AFM) was employed to probe the mechanical properties of polystyrene (PS) microspheres and composite PS/CeO2 core-shell structured microspheres. On the basis of Hertz's theory of contact mechanics, compressive moduli were measured by analyzing force-displacement curves captured on the microsphere samples. The average elastic modulus of the PS microspheres (120 nm in diameter) was 2.8 GPa. The compressive modulus is slightly lower than the modulus of polystyrene bulk materials. The thickness of the CeO2 shell had influence on the mechanical properties of composite microspheres. The modulus of the composite microspheres increased by increasing the thickness of the CeO2 shell. When the CeO2 shell thickness was 8, 12 and 16 nm, the average elastic modulus of the composite microspheres was 7.93, 8.25 and 10.67 GPa, respectively. It is found that the elastic modulus of the composite microsphere and PS core was close.