In-situ monitoring of silica shell growth on PS-b-P4VP micelles as templates using DLS

Abstract

Polystyrene-block-poly(4-vinylpyrdine) (PS-b-P4VP) block copolymer (BCP) was used as a template for the preparation of PS-b-P4VP@SiO2 core-shell particles using an acid catalyzed sol-gel process. The process of silica shell formation and development of shell morphology were studied using a combination of in-situ dynamic light scattering (DLS) and transmission electron microscopy (TEM). The results obtained reveal that shell formation and growth principally involve the following stages: (I) sol assembly around BCP micelles; (II) hydrolysis-condensation reaction accelerated by the protonated P4VP corona of BCP micelles; (III) shell densification; and (IV) shell growth. Present work provides insight into the sol-gel process which takes place in systems containing “reactive” templates, such as protonated PS-b-P4VP micelles, and discloses the mechanism and pathways of silica shell formation. We demonstrate that the whole process can be effectively monitored in-situ using conventional DLS. The results are of significant importance for fabrication of targeted core-shell nanostructures.