A flower-like nano-particle composition including a poly (alkenylbenzene) core and a poly (conjugated diene) or a poly(alkylene) surface layer is provided. The nano-particles have a mean average diameter less than about 100 nm and are substantially free of chain ends. The nano-particles can be modified via, for example, hydrogenation. The nano-particles can advantageously be incorporated into rubbers, elastomers, and thermoplastics.