• Mills, Benjamin
• Grant-Jacob, James A.
• Eason, Robert W.
• Heath, Daniel

Abstract

Nanofoams are generally defined as a class of nanostructured porous materials with <100nm features. They are of interest, as they have many potentially desirable applications in photonics, electronics, chemistry and medicine. Using a femtosecond pulsed laser source to manufacture nanofoam offers the potential to fabricate high porosity nanofoam on the sample surface [1].The fabrication mechanism is understood to be a two-step process, where 1) ionisation from laser ablation of the sample leaves surface debris and 2) subsequent laser pulses reheat and expel the debris leaving a network of solidified vapour trails (nanowires) as they cool. Whilst the substrate is, by necessity, damaged in this process as some of the target material must be sacrificed in order to produce the nanofoam, the amount of damage is small compared to the fabricated volume of nanofoam. Typically less than a 1 micron depth of the target material surface is damaged, whilst the height of the fabricated nanofoam can be greater than 100m, hence with associated density in the range 0.1% to 1% compared to the original material.Currently, we are generally able to fabricate volumes approximately 1mm by 1mm with 100µm depth, per ~15 minute period. The specific volume fabricated depends on the target material, as some materials with higher ablation thresholds require a tighter focus and hence slower fabrication speeds. We have already demonstrated fabrication of glass nanofoam [1], and here, we extend our approach to the fabrication of nanofoam from polymers.We will present our latest results showing fabrication of polymer nanocomposites, along with a recently developed 2D model that has furthered our understanding of the fabrication process over macro (>1µm) size scales.[1] J.A.Grant-Jacob, B.Mills, R.W.Eason, “Parametric study of the rapid fabrication of glass nanofoam via femtosecond laser irradiation”, Journal of Physics D: Applied Physics 2014 Vol.47(5)pp.055105

Topics

• porous
• nanocomposite
• density
• impedance spectroscopy
• surface
• polymer
• glass
• glass
• laser emission spectroscopy
• porosity
• laser ablation
• ionisation