On the mechanochemical activation by ultrasound

Abstract

This is an author version of the contribution published on:On the mechanochemical activation by ultrasound Cravotto G.; Calcio Gaudino E. ; Cintas P Chem. Soc. Rev., 2013,42, 7521-7534 The definitive version is available at:On the mechanochemical activation by ultrasound Cravotto G.; Calcio Gaudino E. ; Cintas P. AbstractChemists have discovered, and recently actively exploited, the fact that subjecting certain molecules to ultrasound waves can bring about transformations that give insight into the correlation between classical tribological processes and the mechanical action caused by collapsing microbubbles when sonic waves propagate through a liquid medium. Chemical transformations induced by ultrasound take place in solution via mechanisms that are markedly different from those associated with molecular activation in the solid state. Both fields, however, share some striking similarities and numerous sonochemical reactions can be rationalized in purely mechanical terms. This tutorial review examines the tribochemical interpretation of sonochemical reactivity and how the multifaceted action of cavitational phenomena determines molecular evolution. A series of case studies involving solids, crystals, and polymers illustrate the mechanical properties of sound waves.

Nanoparticle-assisted ultrasound: A special focus on sonodynamic therapy against cancer

“…Moreover, acoustic cavitation can induce mechanical activation of NPs, such as formation of a mesoporous surface, structural modifications and the creation of fresh highly-reactive metal oxide surfaces. These mechanical activation modes can lead to a higher chemical reactivity of the sonosensitizing NP and thus to a possible higher cellular toxicity [141,142].…”

Interplay Between Mechanochemistry and Sonochemistry

“…Mechanical energy can be harnessed in multiple chemical transformations, such as mechanochromism, analyte detection and self-healing. The basic strategy relies upon the concept of the mechanophore; small structural units embedded into long chain polymers which undergo site-selective scission [6][7][8]12]. Although numerous solid-state and solution methods can be used to activate polymers [11], sonication holds the unique ability of providing shear forces and strain in solution by virtue of the mechanical events associated with cavitational collapse.…”

“…This chapter aims to describe the mechanical bias of cavitational effects and how they are related to conventional mechanochemistry and force-induced physical fields in general. This subject has been well documented over the last decade [5][6][7][8][9], and particular attention has been paid to scenarios such as mechanically responsive polymers [10][11][12], micro-and nano-structured materials [13][14][15], and sonocrystallization [16], which are all expected to have a major impact on the fabrication of novel and smart materials as well as the pharmaceutical industry. Although we shall briefly mention these past achievements, our goal is to focus on the aspects of sono-mechanochemistry that have been overlooked in recent thematic issues.…”

Evaluation of nitrogen effect on ultrasound-assisted oxidative desulfurization process

“…The use of ultrasound (US) in chemistry can intensify chemical reac-tions due to several effects, especially those related to cavitation phenomenon [28][29][30]. Cavitation occurs when mechanical vibrations are generated and transmitted to a liquid medium, producing a series of compression and rarefaction cycles that may exceed the attractive forces of the molecules in the medium, producing cavitation bubbles.…”