Self-Assembly of Nanoparticles from Evaporating Sessile Droplets: Fresh Look into the Role of Particle/Substrate Interaction

Abstract

We studied the dependence of solid deposit shape obtained by free drying of sessile drops on the particles concentration and Derjaguin-Landau-Verwey-Overbeek (DLVO) particle/substrate interaction. In contrast to previous contributions using pH as a control parameter of interactions, we investigated an unprecedentedly wide range of concentrations and particle/substrate DLVO forces by modifying the nature of the substrate and particles as well as their size and surface chemistry whereas long-distance repulsive interactions between particles were maintained for most of the drying time. Our main result is that the different shapes of deposits obtained by modifying the particle concentration are the same in the different regimes of concentration regardless of particle/substrate interaction in the studied range of DLVO forces and particle concentrations. The second result is that, contrary to expectations, the dominant morphology of dry patterns at low particle concentration always shows a dot-like pattern for all the studied systems.

Influence of fluid flows on electric double layers in evaporating colloidal sessile droplets

“…Thus, we conclude that in the presence of a Marangoni flow, the electrostatic interactions do not play an important role in the resulting colloidal particles distribution. This conclusion is in qualitative agreement with the observations presented in [26], where the authors analyzed the role of electrostatic colloidal-substrate interactions within the DLVO theory in colloidal particle distribution inside the droplet and demonstrated its irrelevance. However, in contrast to the mentioned paper, where the authors qualitatively analyzed their experimental data, in this study, we provide a first-principles numerical analysis of charged colloidal particle distribution in a sessile droplet placed on an electrified metal substrate.…”

“…This multiple role complicates the analysis of one single contribution among the others in the pH range around the particle isoelectric point. On the other hand, the experimental results in [20,25,26] suggest that the final morphology of deposits does not depend on substrate-particle interaction.…”

“…In particular, particle-substrate interactions and the role of DLVO forces have been discussed in [16][17][18][19][20][21][22][23][24][25][26]. Many authors agree that attractive particle-substrate forces promote the formation of uniform deposits [17].…”

“…Many authors agree that attractive particle-substrate forces promote the formation of uniform deposits [17]. However, as it was pointed out in a recent work [26], in the case of DLVO forces this statement is based only on few experimental studies [18,19] conducted on a single particle type at a fixed concentration using pH as a means of interaction control. A disadvantage of this approach is that pH controls particle-substrate and particle-particle interactions, or even the affinity of the particles for the liquid-gas interface at the same time.…”

Challenges, Prospects, and Emerging Applications of Inkjet‐Printed Electronics: A Chemist's Point of View

“…Here, the mode of evaporation changes (Figure 3d (4)). For instance, dot‐like patterns surrounded by multi‐ring pattern can be obtained through the combination of CCA mode and CCR mode on hydrophilic substrates with low particle concentrations, regardless of the particle/substrate interaction [60] …”