RAFT-Polymers with Single and Multiple Trithiocarbonate Groups as Uniform Gold-Nanoparticle Coatings

Spectroscopic and electron microscopic analysis of bi-ligand functionalized glycopolymer/FITC–gold nanoparticles

We report a strategy to quantify the relative binding affinity of glycopolymers on FITC-AuNP by release of the FITC via self-assembly process and which was improved by introducing a PEG segment to the glycopolymer of similar functionalities.

Silica core-polystyrene shell nanoparticle synthesis and assembly in three dimensions

Monodisperse silica nanoparticles (SiNPs) grafted with well-defined and highly dense polystyrene brushes are used as building blocks for the formation of three-dimensional (3D) colloidal crystals. By adjusting the refractive indices and the density of the hybrid particles with those of mixed solvents, iridescent microcrystals were formed throughout the entire suspension which were characterised by confocal laser microscopy. These core-shell hybrid particles are not charged and the driving force of the crystallization relies on repulsive forces between the polymer brushes with high grafting density. The interparticle distance is correlated to Bragg's Law and can be controlled by manipulating the grafting density and the length of the polymer brushes. Finally, the uniformity of these unique core-shell particles was exploited to generate 3D assemblies by a rapid and simple process based on centrifugation.

The Structure of Gold-Nanoparticle Networks Cross-Linked by Di- and Multifunctional RAFT Oligomers

Gold nanoparticle (AuNP) network structures featuring particles from the two-phase Brust-Schiffrin synthesis and linear RAFT oligomers of styrene with two and multiple trithiocarbonate (TTC) groups along their backbone have been investigated in detail. Insights into the internal structures of these particle networks could be obtained from small-angle X-ray scattering experiments, showing that primary AuNPs are cross-linked by the employed molecular linker. The extent of AuNP network formation was investigated by means of dynamic light scattering and UV/visible extinction spectroscopy, showing an abrupt attenuation of network formation after a critical degree of polymerization of the cross-linker is exceeded. Analysis of transmission electron micrographs indicated a three-dimensional shape of the particle superstructures, which is evenly filled with the primary AuNPs. From the results obtained in this study, guidelines for the fabrication of nanoparticle networks from the self-assembly with macromolecular cross-linkers are suggested.

A facile synthesis of thermo-responsive Au–polymer hybrid microgels through temperature-induced co-aggregation and self-crosslinking

A facile temperature-induced co-aggregation and self-crosslinking (TICASC) method was developed for preparing thermo-responsive Au–polymer hybrid microgels.

Well-defined colloidal crystal films from the 2D self-assembly of core–shell semi-soft nanoparticles

Silica core–polymer shell particles are obtained from surface mediated RAFT polymerisation and assembled into ordered 2D colloidal crystals.

Plasmonic gold–poly(N-isopropylacrylamide) core–shell colloids with homogeneous density profiles: a small angle scattering study

Four scattering methods covering nearly three orders of magnitude in momentum transfer verify homogeneous network structures in gold–PNIPAM core–shell colloids.

Spherical Gold-Nanoparticle Assemblies with Tunable Interparticle Distances Mediated by Multifunctional RAFT Polymers

A strategy for the controlled assembly of gold nanocrystals into dispersed three-dimensional superstructures is presented. A multifunctional RAFT agent was used to prepare multiblock polystyrene (4.4-17.8 kDa) with trithiocarbonate groups as junctions between the individual blocks. Addition of these polymers to two-phase Brust-Schiffrin gold nanoparticles (4.1 nm) resulted in the formation of stable gold-nanoparticle assemblies dispersed in toluene. TEM analysis revealed that the interparticle distances in these superstructures can be tuned over an unprecedented wide range by employing multiblock polymers with an adjusted degree of polymerization and thus tailored trithiocarbonate distances. Cross-linking of the gold nanoparticles in the assemblies by multifunctional trithiocarbonates was proven by AFM showing partly preserved globular shape after deposition on a solid substrate. The reported strategy is expected to prove useful when interparticle distances in nanoparticle assemblies need to be tuned in a liquid phase or on surfaces.