(527g) Shear-Aligned Assembly Of Colloidal Photonic Crystals

A versatile spin-coating technique for assembling wafer-scale colloidal photonic crystals, along with a large variety of functional nanostructured materials has been developed. The methodology is based on shear-aligning concentrated colloidal suspensions using standard spin-coating equipment. It enables large-scale production of both 3D and 2D non-close-packed colloidal crystals as well as a wide range of nanostructured materials including 3D ordered polymer nanocomposites, macroporous polymers, nanohole arrays, metallic surface gratings, attoliter microvial arrays, 2D magnetic nanodots, metallic pyramid arrays, and more. The spin-coating platform is compatible with standard semiconductor microfabrication, enabling parallel production of micropatterns for potential device applications. The spin-coating process also provides a new route to study the fundamental aspects of shear-induced crystallization, melting and relaxation. Different from simple shear flows in conventional shear cells, the flow in the spin-coating process is inherently non-uniform. The application of assembled periodic nanostructures as surface-enhanced Raman scattering (SERS) substrates will also be discussed.