Sonochemical coatings of nanoparticles on flat and curved ceramic and polymeric surfaces

This article will review the research that has been done in the last decade using ultrasonic waves for coating surfaces. Sonochemistry is a field of research in which chemical reactions occur due to a collapse of an acoustic bubble. The review will present examples limited to coating nanoparticles on ceramic bodies and polymeric surfaces. However, the same technique works also on metallic, glass, and textile surfaces. The excellent adherence of the nanoparticles to the substrate is reflected, for example, in the lack of bleaching of the nanoparticles from the polymeric substrate when deposited by the sonochemical process. Sonochemistry is a research field where waves in the frequency range of 20 kHz - 1 MHz are the driving force for the chemical reactions. The reaction is dependent on the development of an acoustic bubble in the solution. Extreme conditions (temperature >5000 K, pressure >1000 atm and cooling rates >1011 K/sec) are developed when this bubble collapses, thus causing the chemical reactions to occur. The current review will introduce to the reader what kind of surfaces serve as the substrates for the coating. It will present the variety of nanoparticles that have been anchored sonochemically to the surface, and finally it will explain the role of the ultrasonic waves in depositing nanoparticles onto solid surfaces. The review will compare the deposition of newly formed nanoparticles with that of nanoparticles purchased from a commercial source. The first chapter of this review will introduce the reader to the field of sonochemistry. The current review is a continuation of a series of previous reviews published by our group. These reviews introduced the sonochemical technique as a new means for the fabrication of nanomaterials [1], for the use of ultrasonic waves for the doping of nanoparticles into ceramic and polymer bodies [2], and for the microspherization of proteins by a sonochemical process [3]. Other review articles on similar topics have also been published [4-6]. However, no review on using the sonochemical technique for coating surfaces was found in our literature search. In our literature search we will scan for papers published until May 2008. We will try to avoid duplication and the review will not include examples presented in previous reviews.