Gold Nanopaticle/PDMS Composite Exhibiting Anisotropic Plasmon Resonance

概要

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Composite materials of cross-linked poly(dimethylsiloxane) (PDMS) and gold nanoparticles were prepared from vinyl-terminated PDMS precursor using tetrakisdimethylsiloxysilane as cross-linker and hexachloroplatinic acid as catalyst. According to the direction of the electric field, the peak wavelength of absorption spectrum of the stretched sample shifted. This feature is, in principl, induced by the formation of linear arrangements of gold nanoparticles along the stretching direction and consequent resonance of localized surface plasmon. The shift of the peak wavelength changed reversibly with the strain ratio. The simultaneous measurement of stress and birefringence suggested the reversible change of the PDMS network even after large deformation to the non-Gaussian region. Transmission electron microscopy revealed that the gold nanoparticles form spherical primary aggregates with the diameter ranging from tens to one hundred nanometers. On the basis of the results of small angle X-ray scattering experiment, deformation of the primary gold aggregates was thought to be the origin of the linear arrangement of gold nanoparticles. These results suggest the possibility of tuning the resonance property of the surface plasmon by changing the degree of stretching of the material.