Colloids and Surfaces A: Physicochem. Eng. Aspects395 (2012) 145– 151 Contentslists availableat SciVerseScienceDirect Colloids and Surfaces A: Physicochemical and Engineering Aspects j ou r n a l homep ag e : w w w . e l s e v i e r . c o m / l o c a t e / c o l s u r f a Microwave-assistedsynthesis of silver nanoprisms/nanoplates using a “modified polyol process” Thierry Darmanin a , Paola Nativo a , Douglas Gilliland a , Giacomo Ceccone a , CesarPascual a , BarbaraDe Berardis b , Frederic Guittard c,∗ , Franc¸ ois Rossi a,∗∗ a European Commission, Joint Research Centre, Institute for Healthand Consumer Protection, TP203, Via Fermi, 21027Ispra,Italy b IstitutoSuperiore di Sanità, Dipartimento di Tecnologie e Salute, Ambiente e Connessa Prevenzione Primaria,VialeRegina Elena, 00161Rome, Italy c Université deNice– SophiaAntipolis, EquipeChimieOrganique auxInterfaces, Parc Valrose, 06108NiceCedex 2, France a r t i c l e i n f o Articlehistory: Received31 August 2011 Receivedin revisedform 30 November2011 Accepted7 December 2011 Available online 17 December 2011 Keywords: Nanoparticles Nanoprisms Nanoplates Silver Microwave a b s t r a c t In this paper, we report a novel, efficient and versatileprocessto produce high concentrationsof silver nanoprisms, while controlling their size (prism height) and size dispersity,using a “modifiedpolyol pro- cess” (microwave-assisted process). If the formationof silver sphericalparticles, nanocubes or nanowires has alreadybeen reportedusing the classicalpolyol process(reduction of AgNO 3 by ethyleneglycol and in presenceof PVP), here we show that the production of silver nanoprisms/nanoplates is possible by a careful choice in the processparameters and in particular in the reducing agent (ethyleneglycol should be replacedby a reducing agent containing only one hydroxyl reducing group such as ethylene glycol monoalkyl ethers). The synthesis,characterization, the influence of parametersand the mechanismof formationarediscussed in order to correlatethe operational conditionswith the shapeandthe dimension of the nanoparticles. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Due to their fascinating optical properties, the synthesis of nanoparticles of metals such as gold, silver, platinum and copper has been a very active areaof researchin recent years [1–5]. Many of theseoptical propertiesderive from the ability of such small par- ticles to form surfaceplasmons-coherentinteractions betweenthe conduction electronsof the particles and incident electromagnetic waves. A particular characteristic of these oscillations is a strong electric field enhancementat the interface that can lead to a vari- etyof optical phenomenonsuchasamplified Ramanscattering[2a], surface enhancedinfrared absorption [2b], and surface-enhanced fluorescence (SEF)[4] as well as light absorption and most recently circular dichroism [6]. These coherent oscillation modes are concentrated along the interface between the metal particle and the surrounding dielec- tric with strong maxima occurring within certain frequencybands known as the SurfacePlasmon Resonances (SPR). The wavelength of the SPR maxima are critically dependentnot only on the type of ∗ Correspondingauthor. ∗∗ Correspondingauthor. Tel.: +390332785443; fax: +390332785787. E-mail addresses: guittard@unice.fr (F. Guittard), Francois.Rossi@jrc.ec.europa.eu (F. Rossi). metal but also the size, shape,and to a lesser extent the dielectric environment of the particles. These phenomena have been extensively studied using spher- ical nanoparticles which, although relatively easy to synthesize, have resonance bands fixed within narrow wavelength ranges which cannot be greatly modified. To overcome this limitation, it hasbecomedesirableto developmethodsto producenon-spherical particles such as rods, cubes, wires, disks or prisms which can be tailored to produce SPR bands at alternative, higher wavelength rangesthan normally found with spherical particles. The shape of the nanoparticles is very important for the appli- cations. In this case, the ability to produce silver nanoplates or nanoprisms [7–17] is a key point for further developments such as surface-enhancedRaman scattering (SERS), in catalysis or as chemical sensors. On one hand, the methods for the preparation of silver nanoplates or nanoprisms are limited and can be summarized in two global approaches:the conversion of silver spherical particles into nanoprisms by photochemical [7–11] or thermal treatment [13–17]. An example of photochemical conversion is the irradia- tion of an aqueous solution made from AgNO 3 , NaBH 4 , trisodium citrate and polyvinylpyrrolidone (PVP) with different sources of light [9–12]. By a careful selectionof experimentalparameters and particularly the irradiation wavelengths, silver nanoprisms with controllable shape and height or edgelength have been reported. 0927-7757/$– seefront matter ©2011 Elsevier B.V. All rights reserved. doi:10.1016/j.colsurfa.2011.12.020