Observation of fine structure in bicontinuous phase-separated domains of a polymer blend by laser scanning confocal microscopy

Laser scanning confocal micrographs for blends of poly(styrene-ran-butadiene) (SBR) and polybutadiene (PB) demonstrated the existence of fine structures inside one of the well-characterized macroscopically phase-separated bicontinuous domains, in the depth range of the blends belonging to the bulk. The average size of the fine structures was on the submicrometer length scale, while the characteristic spacing of the macroscopically phase-separated domains was on the order of 10 μm. Fluorescence laser scanning confocal micrographs revealed that the fine structures exist only in the SBR-rich phase. Although the driving force for the formation of the fine structures needs to be investigated further, a small amount of PB molecules in the SBR-rich domains seems to play an important role. Illumination and highlights were shed on the advantage of using laser scanning confocal microscopy for investigation of fine structures in the polymer blends.