Surface patterning of nanoparticles with polymer patches

Abstract

Patterning of colloidal particles with chemically or topographically distinct surface domains (patches) has attracted intense research interest1–3. Surface-patterned particles act as colloidal analogues of atoms and molecules4,5, serve as model systems in studies of phase transitions in liquid systems6, behave as ‘colloidal surfactants’7 and function as templates for the synthesis of hybrid particles8. The generation of micrometre- and submicrometre-sized patchy colloids is now efficient9–11, but surface patterning of inorganic colloidal nanoparticles with dimensions of the order of tens of nanometres is uncommon. Such nanoparticles exhibit size- and shape-dependent optical, electronic and magnetic properties, and their assemblies show new collective properties12. At present, nanoparticle patterning is limited to the generation of two-patch nanoparticles13–15, and nanoparticles with surface ripples16 or a ‘raspberry’ surface morphology17. Here we demonstrate nanoparticle surface patterning, which utilizes thermodynamically driven segregation of polymer ligands from a uniform polymer brush into surface-pinned micelles following a change in solvent quality. Patch formation is reversible but can be permanently preserved using a photocrosslinking step. The methodology offers the ability to control the dimensions of patches, their spatial distribution and the number of patches per nanoparticle, in agreement with a theoretical model. The versatility of the strategy is demonstrated by patterning nanoparticles with different dimensions, shapes and compositions, tethered with various types of polymers and subjected to different external stimuli. These patchy nanocolloids have potential applications in fundamental research, the self-assembly of nanomaterials, diagnostics, sensing and colloidal stabilization.

Multiscale Nanoparticle Assembly: From Particulate Precise Manufacturing to Colloidal Processing

“…[5] However, these effects are only accessible, if the nanoparticles preserve their initial properties in the end product, which is in strong contrast to ceramic processing, where the final piece is densified and the particles are sintered together. Many aspects of nanoparticle assembly were presented, including the synthesis of precisely defined building blocks such as gold nanoparticles with high shape uniformity and monodispersity, [8] the influence of shape on the assembly behavior, [9] DNA-directed assembly, [10] responsive nanoparticle assemblies, [11] surface patterning of nanoparticles, [12] or chiral nanoparticle assemblies mimicking biological structures. [6] The big challenge is to place every nanoparticle precisely at the right spot over several length scales, basically involving nanoparticulate precise manufacturing, in analogy to atomically precise manufacturing.…”

Limiting the valence: advancements and new perspectives on patchy colloids, soft functionalized nanoparticles and biomolecules

“…26,27 The particular features of such self-assembled patchy aggregates are extremely soft interactions and possible fluctuations in the number, position and/or size of the patches. Not all routes towards functionalized units can be classified in a neat way: for instance, patchy particles obtained by grafting polymer brushes to the surface of colloidal particles 28 are the result of a self-organization process, but those patchy units do not have the degrees of freedom associated to a flexible patchiness. Another example where the proposed classification becomes ambiguous is represented by a new type of polymeric networks named vitrimers: vitrimers are malleable materials that can rearrange their topology without changing their average connectivity; 29 the phase behavior of these systems has been recently described with a patchy model that combines a non-flexible particle geometry with a bond switching dynamics that mimics the bond exchange mechanism that is at the basis of the extraordinary properties of vitrimers.…”

Vector assembly of colloids on monolayer substrates

“…The most successful and popular fabrication approach so far is to decorate the particle surface with sticky patches of defined chemistry, size and location82123. The patches endow the particles with bonding directionality and valence so that the colloidal atoms can assemble into simple colloidal molecules analogous to H 2 , CH 4 and CH 2 =CH 2 (ref.…”