Solvent-induced assembly of mono- and divalent silica nanoparticles

Abstract

Particles with attractive patches are appealing candidates to be used as building units to fabricate novel colloidal architectures by self-assembly. Here, we report the synthesis of one-patch silica nanoparticles, which consist of silica half-spheres whose concave face carries in its center a polymeric patch made of grafted polystyrene chains. The multistage synthesis allows for a fine control of the patch-to-particle size ratio from 0.23 to 0.57. The assembly of the patchy nanoparticles can be triggered by reducing the solvent quality for the polystyrene chains. Dimers or trimers can be obtained by tuning the patch-to-particle size ratio. When mixed with two-patch nanoparticles, one-patch nanoparticles control the length of the resulting chains by behaving as colloidal chain stoppers. The present strategy allows for future elaboration of novel colloidal structures by controlled assembly of nanoparticles.

Surface Engineering and Programmed Self-Assembly of Silica Nanoparticles with Controllable Polystyrene/Poly(4-vinybenzyl azide) Patches

“…When large amounts of TEOS were required, the growth reaction was sequenced in several stages, in order to avoid the occurrence of silica secondary nucleation. 1- and 2-patch silica NPs with S ranging from 0.21 to 1.54 and 0.31 to 1.00 were derived from silica/PS monopod- and bipod-like NPs, respectively, prepared through a seeded-growth emulsion polymerization of styrene after silica regrowth and dissolution of the just physically entangled PS macromolecules. ,,,, Following the same method, in this work, 3- and 4-patch silica NPs with S ranging from 0.26 to 0.64 and 0.15 to 0.55 were first prepared, respectively (Figure , Table S1 and S2). The size of PS nodules reduced from 145 to 35 nm for tripods, from 140 to 130 nm, respectively (Table S1 and S2).…”

“…Patchy silica nanoparticles (PSN) with a controllable patch-to-particle size ratio (S) were collected after specific silica regrowth and solvent rinsing to remove physically entangled PS chains reported by Ravine. − However, at least one dimple remained in patchy particles after solvent rinsing when S is small, ,,,, which results in discontinuity of particle surfaces and limits their follow-up assembly. To solve the above issue, we designed constituent building blocks at a smaller scale to create new materials distinguished with the ones we obtained before.…”