NOVEL METHOD FOR PREVENTION OF CRACKS IN NANOPARTICLE FILMS

摘要

Thin films composed of nanoparticles possess functionalities useful for applications, such as energy conversion and storage, drug delivery, and biosensing. Often these functionalities only emerge when the films are free of defects, such as cracks. Cracks develop during the mechanism of film formation because the normal stress imposed by the solvent through interfacial tension induces a transverse tensile stress in the plane of the film that exceeds the strength of the close-packed network of substrate-bound particles. It was demonstrated that tensile stress at the onset of cracking depends on film thickness, particle shear modulus, particle packing configuration, and the liquid-air interfacial tension. For a given particle type, solvent, and film compaction mechanism, cracking is therefore observed above a critical film thickness. Thus, extensive researches are being carried out by researchers to find an alternative approach to improve cracking resistance and develop high strength nanoparticle films for industry applications.