Towards smart self-assembly of colloidal silica particles through diblock copolymer crystallization

An innovative associative strategy, crystallization-driven self-assembly, is discussed for hybrid inorganic-organic materials. We report the use of a semicrystalline poly(butadiene)-b-poly(ethylene oxide)(PB-b-PEO) diblock copolymer (BCP) that self-assembles with silica nanoparticles (NPs) in a selective solvent. In ethanol, at 60 °C, that is above the melting temperature Tm of the PEO block, the BCP forms amorphous spherical micelles consisting of a liquid PEO-corona and a core of PB-chains. The controlled formation of hybrid structures is achieved using temperature quenches below Tm of the BCP where the PEO block crystallizes in the micellar corona, leading to the formation of lamellar structures. The crystallization further dictates the spatial distribution and drives the self-assembly of the colloidal particles into the BCP lamellar domains. Such association is tunable and reversible, following the crystallization temperature Tc. The employed method offers new perspectives for the directed self-assembly of colloidal particles through an underlying controlled crystallization process of semicrystalline BCP in solution.