Characterization of ordered array of micropores in a polymer film

Abstract

Microporous polymer films prepared by templating “breath figures” tend to have closely packed, hexagonal arrays of pores. We characterize the hexagonal order of the structured films using Fraunhofer diffraction patterns in reciprocal space, as well as with the use of Voronoi diagrams and bond-orientational correlation functions using real space images. The average spacing of the pores over a wider area can be calculated by two-dimensional Bragg equation, while the analysis of microscope images provides a direct measurement of the average open pore size and its distribution. The use of bond-orientational correlation function is particularly useful in quantifying the order of various films formed under various conditions. Further, we show how the sequential ordering of water drops formed during breath-figure-templated assembly process can also be characterized using Voronoi analysis and bond orientational correlation function.