Nanotech Self-Assembly Enables Novel Soft Materials With Special Properties

In order to help materials engineers to make ever better fabrics and soft materials from novel composites, scientists in the EU are developing design tools and tailor-made functions for soft materials that will soon be possible with cost- and energy-efficient controlled self-assembly.

Nanoparticles (NPs), materials on the scale of billionths of a metre, often have properties much different from those of the same material in bulk form. Their incorporation into composites is poised to revolutionise material design.

Self-assembly of nanoparticles (NPs) is an interesting phenomenon that, if suitably controlled, is making large-scale, cost-effective manufacture of tailor-made nano-based composites a real possibility. Scientists initiated the EU-funded project 'Toolbox for directed and controlled self-assembly of nano-colloids' (NANODIRECT) to help materials scientists and engineers do just that.

Gold and silver NPs are particularly interesting for their properties relating to light manipulation (plasmonic properties). Scientists have directed their self-assembly into hierarchical structures using a microscopic template with regular geometries and achieved excellent control over very specific optical responses. Gold nanorods formed end-to-end interactions and self-assembly into standing superlattices.

Rod-like virus particles have been chemically modified to control their properties, behaving like sticky rod-like colloids to study the effects of particle shape on gel properties. The modified viruses are now being used as model systems in soft condensed matter physics. Polymeric NPs with a dumbbell shape have also been synthesised and studied, and a simple yet versatile method for directed self-assembly of anisometric polymeric particles has been developed.

Scientists are studying the migration of NPs in visco-elastic matrices, as well as the effects of various directing tools. Electric fields have been particularly well characterised to date leading along the way to the development of novel experimental and theoretical tools. Assembly at liquid interfaces has been particularly promising for scale-up to industrial conditions. The scientists are also characterising the relationship of structure and chemistry with dispersion.

Given the need for exquisite control of self-assembly in order to tailor properties, NANODIRECT is complementing conventional chemical directing methods with the use of different fields and templating agents. Ultimately, scientists expect to deliver a novel toolbox to aid materials engineers in the design of nano-based colloidal composites with high impact in emerging applications, including plasmonics. -- © European Union, CORDIS