Ligand-Assisted self-assembly of colloidal Ag2S nanoparticles

Abstract

Over the last decade, great attention of researchers has been focused on nanoscale self-assembly due to increasingly technology-relevant applications. Pattern formation by colloidal droplet evaporation is one of the fascinating subjects to study. A deep understanding of physical and chemical processes of the deposited structure formation allows the development of bioprinting methods, nanoarchitectures for optics and electronics, methods for detecting the state of peptides, proteins, etc. In the present work, the effect of organic ligands (MPS, BSA, GSH, EDTA, TG) on Ag2S NP self-assembly during solution droplet evaporation was investigated. The synthesis conditions were optimized to minimize or neglect the contribution of surface roughness, substrate thermal conductivity, NP shape and size, type of solvent. Properties of a stabilizer, such as molecular length, reactivity, tendency to polycondensate or chelate, and their relative concentration affect the nanoparticle–nanoparticle interactions, which results in several types of pattern formation. The dominant forces in different regions of the evaporated droplet via ligand were discussed. The models of pattern formation were proposed. Thus, depending on the ligand, Ag2S NPs tend to form rings (MPS, BSA), concentric rings (BSA), net like structures (TG), and chains (MPS, TG). In addition, it was shown that replacing water with deuterium can significantly change self-organized architectures.