Abstract

The formation of purely metallic meso-porous metal thin films by partial interface coalescence of self-assembled metal nano-particles across aqueous solutions of Pluronics triblock lyotropic liquid crystals is demonstrated for the first time. Small angle X-ray scattering was used to study the influence of the thin film composition and processing conditions on the ordered structures. The structural characteristics of the meso-structures formed demonstrated to primarily rely on the lyotropic liquid crystal properties while the nature of the metal nano-particles used as well as the their diameters were found to affect the ordered structure formation. The impact of the annealing temperature on the nano-particle coalescence and efficiency at removing the templating lyotropic liquid crystals was also analysed. It is demonstrated that the lyotropic liquid crystal is rendered slightly less thermally stable, upon mixing with metal nano-particles and that low annealing temperatures are sufficient to form purely metallic frameworks with average pore size distributions smaller than 500 nm and porosity around 45% with potential application in sensing, catalysis, nanoscale heat exchange, and molecular separation.

Highlights

  • Meso-porous metal frameworks, with average pore size distributions below 500 nm, exhibit unique surface to volume ratios whereby the metal natural’s optical and catalytic properties and ductility become dramatically enhanced [1]

  • The simultaneous removal of the Lyotropic liquid crystals (LLC) system and coalescence of hydrophilic NPs should lead to a meso-porous system where pores are formed within the sites of the initial hydrophobic particles (Figure 1)

  • The synthesis of meso-porous metal frameworks was demonstrated by controlled metal

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Summary

Introduction

Meso-porous metal frameworks, with average pore size distributions below 500 nm, exhibit unique surface to volume ratios whereby the metal natural’s optical and catalytic properties and ductility become dramatically enhanced [1]. The dispersion of NPs across a semi-rigid sacrificial ordered template, typically an amphiphilic polymer gel [12,13,14,15,16,17,18,19] is a highly efficient route to process meso or nano-scale materials This technique offers much greater crystallinity and pore morphology control than conventional nano-fabrication techniques, such as foaming or de-alloying, due to the natural ordered properties of the templating LLC matrix. Frameworks have led to highly promising architectures for fast heat dissipation [23], energy generation [24], sensing [25], or molecular fractionation [1,26,27,28,29] Such nano-porous structures that integrate the properties of the bulk metal on long range order and maintain those obtained at the nanoscale have not yet been achieved. The impact of the annealing conditions on the stability of the ordered phases formed upon NPs incorporation across the LLC matrix will be discussed in light of the final material morphology and small angle X-ray scattering (SAXS) data and for the first time related to the dynamic of single particles coalescence

Results and Discussion
LLC—Metal NP Sample Preparation
Characterization Techniques
Conclusions

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