Self-assembly of colloidal polymers from two-patch silica nanoparticles

Abstract

We report the formation of colloidal polymers consisting of disk-like silica nanoparticles (NPs) with polystyrene (PS) chains at the bottom of their two cavities assembled through reduction of the solvent quality for the PS chains and linked by hydrophobic associations. We show that this NPs assembly exhibits a two-stage process involving reaction-controlled polymerization and diffusion-controlled polymerization. Colloidal polymer networks are produced by the incorporation of three-patch NPs, which serve as branching points between the colloidal chains. By co-assembling preformed homopolymers composed of patchy NPs of different sizes or surface chemical groups, block copolymers are also achieved. This study provides insight into the process of self-assembly of two-patch NPs by precisely designing the components to generate colloidal analogues of linear macromolecular chains.

Linear Assembly of Two-Patch Silica Nanoparticles and Control of Chain Length by Coassembly with Colloidal Chain Stoppers

“…We found that k = 3.77•10 5 L.mol -1 .s -1 and 1.80•10 5 L.mol -1 .s -1 for the polymerization of 105-nm and 130-nm 2-PSN, respectively. These values are of the same order of magnitude as that found for the chains obtained from 190-nm 2-PSN 25 and for the copolymerization of inorganic nanoparticles. 2 At longer times (t > 5 h), does not vary linearly with time anymore (Figure 4a).…”

“…We previously showed that we assembled 155-nm and 190nm 2-PSN in chains by adding 30 vol.% of salty water into the NPs dispersion in THF, thereby reducing both the electrostatic repulsions between NPs due to negatively charged silanolate groups at their surface and solvent quality for the PS chains (Figure 2e-f and Figure S6). 25 Similar results were obtained when changing the salty water concentration, as shown in Figure 2i. We thus decided to investigate the behavior of the 2-PSN with smaller sizes by adding salty water as bad solvent for the PS chains.…”

“…We recently reported the formation of colloidal polymers through the solvent-induced assembly of two-patch silica nanoparticles (2-PSN). 25 Herein, we investigate for the first time the assembly behavior of 2-PSN with different patch-to-particle size ratios and we show that chaining strongly depends on the composition of the solvent mixture employed during the incubation. Our approach comprises three main steps (Scheme 1): synthesis of binary silica/PS bipods by emulsion polymerization; precise regrowth of the silica core of the obtained bipods and dissolution of their PS nodules to form 2-PSN with a well-defined morphology; fine tuning of the solvent composition to promote their polymerization.…”

Directional and Reconfigurable Assembly of Metallodielectric Patchy Particles

“…The formation of the colloidal chains finishes within seconds to minutes, following a step-growth kinetics, according to the direct observation (Figure a,b and Movie S1) and statistical analyses (Figure S2). Initially, the particles assemble by forming directional patch–patch bonds.…”

Solvent-induced assembly of mono- and divalent silica nanoparticles

“…By using postassembly ligand photo-cross-linking [26] or by adding monofunctional nanospheres into a suspension of bifunctional gold nanorods [27], it was shown that the average degree of polymerization of the resulting chains could be controlled. The reduction of the solvent quality may be also employed to induce the assembly of silica/polystyrene dumbbells [28] and silica nanoparticles with two PS patches (2-PSN) [29] into multipodlike clusters and colloidal chains, respectively. Here, we report that one-patch silica nanoparticles (1-PSN) with a well-controlled patch-to-particle size ratio (PPSR) assemble into dimers or trimers by following the same strategy.…”