Journal Article

Guided hierarchical co-assembly of soft patchy nanoparticles

Schmalz, Holger, Müller, Axel H. E., Gröschel, André H., Walther, Andreas, Löbling, Tina I., Schacher, Felix H.

2013

Overview

Different polymers can be used in combination to produce coexisting nanoparticles of different symmetry and tailored to co-assemble into well-ordered binary and ternary hierarchical structures. Patched-up assemblies There is considerable practical interest in developing the tools to fabricate multicomponent artificial systems that mimic the hierarchical ordering seen in the natural world — complex biomaterials can be assembled from the simple but precisely defined molecular building blocks. André Gröschel and colleagues have developed a bottom-up approach that's a step in that direction. Previously they designed simple linear polymers that self-assemble in solution to produce monodisperse nanoparticles with well-defined interaction anisotropies — surface 'patches' that direct self-assembly of the particles into larger structures. Now they show that different polymers can be used in combination to produce coexisting nanoparticles of different symmetry and tailored to co-assemble into well-ordered binary and ternary hierarchical structures. Possible applications of this approach range from smart materials to photonics. The concept of hierarchical bottom-up structuring commonly encountered in natural materials provides inspiration for the design of complex artificial materials with advanced functionalities 1 , 2 . Natural processes have achieved the orchestration of multicomponent systems across many length scales with very high precision 3 , 4 , but man-made self-assemblies still face obstacles in realizing well-defined hierarchical structures 5 , 6 , 7 , 8 , 9 , 10 , 11 . In particle-based self-assembly, the challenge is to program symmetries and periodicities of superstructures by providing monodisperse building blocks with suitable shape anisotropy or anisotropic interaction patterns (‘patches’). Irregularities in particle architecture are intolerable because they generate defects that amplify throughout the hierarchical levels. For patchy microscopic hard colloids, this challenge has been approached by using top-down methods (such as metal shading or microcontact printing), enabling molecule-like directionality during aggregation 12 , 13 , 14 , 15 , 16 . However, both top-down procedures and particulate systems based on molecular assembly struggle to fabricate patchy particles controllably in the desired size regime (10–100 nm). Here we introduce the co-assembly of dynamic patchy nanoparticles—that is, soft patchy nanoparticles that are intrinsically self-assembled and monodisperse—as a modular approach for producing well-ordered binary and ternary supracolloidal hierarchical assemblies. We bridge up to three hierarchical levels by guiding triblock terpolymers (length scale ∼10 nm) to form soft patchy nanoparticles (20–50 nm) of different symmetries that, in combination, co-assemble into substructured, compartmentalized materials (>10 μm) with predictable and tunable nanoscale periodicities. We establish how molecular control over polymer composition programs the building block symmetries and regulates particle positioning, offering a route to well-ordered mixed mesostructures of high complexity.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/301/357/341 / 639/301/923/916 / 639/301/923/966 / Advanced materials / Analysis / Anisotropy / Applied sciences / Atoms & subatomic particles / Biomedical materials / Composition / Crystallization / Exact sciences and technology / Humanities and Social Sciences / letter / multidisciplinary / Nanoparticles / Organic polymers / Physicochemistry of polymers / Polymers / Properties / Properties and characterization / Ratios / Science / Solution and gel properties / Structure