In this work, using different microscopic techniques, and tensile testing, we investigate the micro-deformation processes in the blends and nanocomposites based on a highly asymmetric star shaped polystyrene/polybutadiene block copolymer. As one of the blends and composites components, we use general purpose polystyrene (GPPS) and organophilic modified boehmite nanoparticles, respectively. The emphasis has been put on the analysis of the impact of morphology on the micromechanical behaviour of the blends. After mixing with standard polystyrene, these copolymers form typical droplet morphologies. The incorporation of boehmite nanofiller with different types of surfactants into the binary blends was found to affect the micromechanical properties in various ways, the most optimum morphology for the enhancement of the toughness being the finest dispersion of the spherical nanoparticles less than 50 nm in diameter which initiated intense plastic deformation of the blend.