Microstructural and optical characterization of polymer nanotemplates with different morphologies

Abstract

The block copolymer (BCP) templates with nanoscale structures and diverse morphologies have attracted much attention for nanofabrication in photonic and plasmonic research fields. Herein, PS-b-PMMA BCP nanotemplates with different morphologies, including the patterns of hexagonal hole arrays, fingerprint stripes, and their mixture, are successfully prepared for in-depth microstructural and optical characterizations. Apart from direct microstructure observations and component characterization, ellipsometric measurements are mainly applied to characterize structural and optical evolution of these BCP nanotemplates undergoing different preparation stages. Interestingly, among different BCP nanotemplates, two typical reflectance peaks in the ultraviolet region (200–250 nm) are distinctly different from each other, due to their PS- and thickness-dependent optical behaviors. With the preparation proceeding, there are synchronous diminution in the intensity of the two peaks, accompanying with an obvious blue-shift for the shorter wavelength peak. In addition, the variation of refractive index and ellipsometric parameters greatly demonstrates morphology-dependent optical behaviors among different BCP nanotemplates. Finally, Au-covered BCP nanotemplates present the distinct template-morphology-dependent visible-light responses, demonstrating different light-matter interactions occurred in their plasmonic Au nanostructures.