Directed Assembly of High Aspect Ratio Nanoparticles for Hierarchical Materials

Lead Research Organisation: Imperial College London
Department Name: Dept of Chemistry

Abstract

High aspect ratio nanoparticles (HARNs), such as nanorods and nanotubes, span both the micron and the nano domains, and are especially critical for hierarchical materials. The extra degrees of freedom associated with orientation create appealing opportunities but additional challenges. The implicit anisotropy of HARNs is reflected both in their intrinsic properties and in the rich structural variety of assemblies containing them. For example, while transverse quantum confinement can generate unique transport properties along the long axis of an individual nanowire, it is also possible to introduce internal structural or compositional variation, creating complex functionality within a single HARN . On the other hand, in order to use its inherent functionalities, the HARN must be integrated into a wider structure. From this perspective, high aspect ratio allows the formation of open networks or scaffolding with adjustable density, orientation, connectivity, and length scale. If the assembly process can be controlled, there is scope for complicated specific architectures, with ordered branches or junctions in the scaffolding, optimised for given applications. One way to envision the opportunity is to imagine the richness of metal organic frameworks (MOFs) multiplied by the structural and functional diversity that could be introduced by using HARNs as linking struts at a range of lengthscales. Note that although the term 'HARNS' could be taken to include oblate particles, such as nanoclay platelets, the focus here is on prolate rods, tubes, and fibres.At a conceptual level, the assembly of hierarchical materials represents the next challenge in materials science; mastering methods to control matter fully, across the lengthscales, will open up new vistas of science and application. On the other hand, the simplest networks of HARNs are already extremely relevant to a wide range of applications; existing examples include aligned CNT arrays for capacitor electrodes, aerospace epoxy nanocomposites with ultra-low electrical percolation thresholds, and efficient electron collection in titania nanorod photovoltaics. These current networks are almost all randomly designed, or at best, uniaxially oriented. The rational design of HARN architectures across different lengthscales will yield radical improvements in structural and functional performance.

Publications

10 25 50
 
Description The goal was to develop highly-ordered, hierarchical materials, using high aspect ratio nanoparticles (HARNs) as fundamental building blocks to create functional structures designed across different lengthscales. Three work packages addressed the preparation of new, well-defined high aspect ratio nanoparticles, their modification with selective or supramolecular chemistry, and their assembly into high order structures. Carbon nanotubes and titania were selected as the key materials due to their impressive properties and range of potential applications. In both materials systems, significant progress was made. Individual nanotubes were solubilised, purified, and functionalised using chemical reductions in ammonia (developed with Skipper/Howard at UCL) and a new electrochemical charging route. The synthesis of titania nanorods has been refined, and extended to the formation of 2d platelets with detailed mapping of reaction conditions and advanced TEM analysis of structure and electronic properties. The original ambitious supramolecular linking scheme has been demonstrated and used to purify nanotube fractions by endohedral affinity and to assembly defined junctions, as protected by a patent filing. Methods to generate more general multiscale networks of carbon nanomaterials have been developed and subsequently applied to the preparation of catalyst supports and electrochemical electrodes for energy generation and storage.
Exploitation Route General methods for the fabrication of improved nanomaterials are of wide relevance. For example, the titania nanorods and especially nanoplatelets are photocatalytically active, and potentially relevant to a range of solar cells, self-cleaning, and environmental clean-up applications. True solutions of undamaged carbon nanotubes are immediately useful for transparent conductors to replace ITO, as well as other thin film electronics applications, electrochemical electrodes (fuel cells, supercapacitors, etc), catalyst supports, and composites. Hierarchical assemblies are particularly efficient in many contexts. Directed assembly to form specific junctions has long term potential to advance nanoelectronics.
Sectors Aerospace, Defence and Marine,Chemicals,Construction,Electronics,Energy,Environment

 
Description The production of reductively charged nanocarbons, partly developed during this grant, was patented and licensed, leading to the launch of a commercial product targeted at the electronics industry in 2013. Further developments of the technology are anticipated. Work on supramolecular assembly is under discussion with a major international electronics company. The chemistry developed and extended in this grant has been widely adopted by others, including for making solar cells and high strength fibres.
First Year Of Impact 2013
Sector Aerospace, Defence and Marine,Chemicals,Electronics
Impact Types Economic

 
Description Leverhulme Trust
Amount £238,749 (GBP)
Funding ID F/07 058/BT 
Organisation The Leverhulme Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2011 
End 09/2014
 
Description NIEHS
Amount £268,500 (GBP)
Funding ID 1U19ES019536-01 
Organisation National Institute of Environmental Health Sciences 
Sector Public
Country United States
Start 05/2010 
End 05/2015
 
Description LG 
Organisation LG Electronics
Country Korea, Republic of 
Sector Private 
PI Contribution Building on the initial work and filing in the group, an industrial research project has been awarded (stc) to develop the technology towards applications.
Collaborator Contribution Financial support
Impact Collaborative research due to start shortly
Start Year 2019
 
Description Linde 
Organisation Linde Group
Country Global 
Sector Private 
PI Contribution Developed a technology in partnership and licensed to the company
Collaborator Contribution Technical discussion, hiring a group member, supplying samples and information
Impact Licensed technology and product release.
 
Description Thomas Swan and Co Ltd 
Organisation Thomas Swan and Co Ltd
Country United Kingdom 
Sector Private 
PI Contribution Long standing partnership developing technology and licensing it
Collaborator Contribution Development of synthesis and processing routes relevant to new company products. Advice and discussion. CASE studentships (3)
Impact New nanomaterials products.
 
Description University College London 
Organisation University College London
Country United Kingdom 
Sector Academic/University 
Start Year 2005
 
Title CROSS-LINKED GRAPHENE NETWORKS 
Description Directly linked graphene networks and aerogels. 
IP Reference US2015122800 
Protection Patent granted
Year Protection Granted
Licensed No
Impact .
 
Title Carbon nanotube aerogels and xerogels and xerogels for CO2 capture 
Description Carbon nanotube aerogels and xerogels and xerogels for CO2 capture 
IP Reference GB2516565 
Protection Patent granted
Year Protection Granted 2015
Licensed No
Impact .
 
Title Cross-Linked Carbon Nanotube Networks 
Description Cross-Linked Carbon Nanotube Networks 
IP Reference US2014012034 
Protection Patent granted
Year Protection Granted 2014
Licensed No
Impact .
 
Title Dispersion method 
Description Dispersion of graphene platelets by charging methods 
IP Reference GB20110010937 
Protection Patent granted
Year Protection Granted 2011
Licensed No
Impact .
 
Title Graphene and graphene oxide aerogels/xerogels for CO2 capture 
Description Graphene and graphene oxide aerogels/xerogels for CO2 capture 
IP Reference GB2515425 
Protection Patent granted
Year Protection Granted 2014
Licensed No
Impact .
 
Title METHOD FOR DISPERSING AND SEPARATING NANOTUBES 
Description METHOD FOR DISPERSING AND SEPARATING NANOTUBES 
IP Reference US2011287258 
Protection Patent granted
Year Protection Granted 2011
Licensed Yes
Impact .
 
Title METHOD FOR SEPARATING NANOMATERIALS 
Description Electrochemical charging method to disperse carbon nanomaterials 
IP Reference WO2010001125 
Protection Patent granted
Year Protection Granted 2008
Licensed Yes
Impact .
 
Title Purification method 
Description Purification of nanomaterials using a chemical charging method 
IP Reference WO2012131294 
Protection Patent granted
Year Protection Granted 2013
Licensed Yes
Impact .
 
Title SELF-ASSEMBLY OF NANOTUBES 
Description Self-assembly of nanotube networks by endohedral means 
IP Reference WO2015063341 
Protection Patent application published
Year Protection Granted 2015
Licensed No
Impact .