Flow synthesis of silver nanowires

Thomas William Phillips, John De Mello, Martin Heeney, Paul Stavrinou, Engineering And Physical Sciences Research Council
This thesis reports the development of a droplet-based flow synthesis of silver nanowires. Using traditional batch methods of production it can be difficult to achieve the consistent reaction conditions needed to obtain nanocrystals with the desired properties. Microfluidic reactors offer superior control over reaction conditions and enable the scalable and continuous production of consistent and monodisperse nanoparticles. Silver nanowires are typically synthesised using the polyol reaction,
more » ... ere silver nitrate is reduced in hot ethylene glycol. Previous reports describing the synthesis of silver nanowires have come to contradictory conclusions about the conditions needed for growth. In this thesis a hot-injection polyol synthesis was adapted to a straightforward heat-up procedure for the production of silver nanowires. The success of the reaction was found to be dependent on the batch of ethylene glycol used. The modified synthesis enabled the development of a flow process using a polytetrafluoroethylene tubing-based droplet-based flow reactor. The reactor produced consistent silver nanowires over an eight hour period with no sign of reactor fouling. The reactor was used to investigate the effect of varying the reaction temperature, residence time, and concentration of iron nitrate and sodium chloride additives on the length of the silver nanowires produced. This thesis finishes with the development of an inline liquid-liquid separator based on the selective wetting and permeation of a porous capillary by one of the liquids. Efficient separation of aqueous-organic, aqueous-fluorous, and organic-fluorous flows was achieved over a wide range of flow rates. The separator was successfully applied to the inline aqueous-organic extraction of the pH indicator 2,6-dichloroindophenol. The organic extract and aqueous raffinate were separated using a porous capillary. UV-visible absorption spectroscopy showed the concentration of indicator in the aqueous raffinate to be less than one percent of its original value, confir [...]
doi:10.25560/64907 fatcat:6i5ip4xb3bg33nsn75wcd66vne