Scalable Spark Ablation Synthesis of Nanoparticles: Fundamental Considerations and Application in Textile Nanofinishing

A major challenge in nanotechnology is that of determining how to introduce green principles when assembling individual nanoscale elements to create multifunctional working devices. This dissertation focuses on fundamentals (Part A), scaling-up (Part B) and application (Part C) of nanoparticles with sub-10 nm in size produced by ambient spark ablation, which is a scalable and environmentally benign process, providing great versatility in producing inorganic nanoparticles consisting of a wide variety of conducting or semiconducting materials with virtually unlimited mixing possibilities. In Part A, a new ‘singlet’ concept has been introduced, which rules out the pseudo-paradigm: continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration. Subsequently, a general approach has been developed to describe the size distributions of singlet particles as a function of the process conditions. In Part B, a newly developed high-frequency spark yields a series of monometallic and bimetallic nanoparticles, sub-10 nm (primary) particles and well-defined chemical composition, providing a green and versatile platform for manufacturing key building blocks toward industrial scale. To improve the uniformity of nanoparticles, inhibition of ‘splashing’ particles (larger than 100 nm) has been successfully achieved by using an external magnetic field within the inter-electrode gap. The resulting Lorenz force deflects the continuous glowing current, onto which sparks are superimposed, thereby avoiding the sparks to strike the same point of electrode surface. To explore internal nanoparticle mixing, a model developed here links the composition of nanoparticles to spark oscillations. In Part C, by integrating gas-phase nanoparticle syntheses into textile nanofinishing, a number of constraints encountered in traditional wet-finishing processes, can be circumvented while creating a new class of fabrics. As proof of this concept, Ag nanoparticles are deposited onto a range of textiles, imparting high antimicrobial activities and exhibiting good washing durability. Accounting for the green, scalability and versatility of the technique used here as well as its compatibility with the existing fabrication processes, the generated nanoparticles bear a great potential for creating multifunctional working devices.