Three-dimensional structural analysis of rubber materials using scanning electron microscopy equipped with focused ion beam

A 3D lamellar structure of a poly(styrene-block-isoprene) block copolymer has been studied at the sub-micrometer and micrometer scale by a scanning electron microscope equipped with a focused ion beam system (FIB-SEM). The specimen, stained by an OsO₄ water solution, was fabricated by the Ga ion beam with the suitable acceleration voltage (30 kV) and was observed by the electron beam with the optimized acceleration voltage (1.6 kV). These experimental conditions enabled us to take clear SEM images without significant beam damages, and the 3D lamellar structure of the SI block copolymer was successfully reconstructed. The size of reconstructed image by the FIB-SEM was 6.0 × 6.0 × 4.0 μ,m³, which was larger than the transmission electron microtomograhy data, 3.8 × 3.9 × 0.24 μm³ by a factor of ca. 40. The result indicates that 3D reconstruction by means of FIB-SEM is quite useful for 3D direct observations and analyses of polymeric materials at the sub-micrometer and micrometer scale.