Photopolymerization-assisted self-assembly as a strategy to obtain a dispersion of very high aspect ratio nanostructures in a polystyrene matrix

•A synthesized poly(styrene-block-ε-caprolactone) block copolymer was dissolved in styrene.•The solution was slowly photopolymerized at room temperature during four days.•Long crystalline nanoribbons dispersed in a PS matrix were obtained.•Nanoribbons were generated through a stepwise micellization-crystallization-growth process.•Crystallization of PCL blocks played a dominant role in determining the morphology.