Influence of polymer chain length and concentration on the deposition patterns of linear diblock copolymer solution nanodroplets

Abstract

We perform molecular dynamics simulations to study deposition patterns of linear diblock copolymer solution nanodroplets on a solid surface (a wall). The current work mainly investigates the influence of the polymer concentration, chain length, and solvent–wall interactions. Polymer block–wall interaction strengths (ε_Pa(Pb)W) are modified to simulate polymer blocks with different adsorption behaviors, such as weak adsorbable (ε_Pa(Pb)W = 0.6), moderate adsorbable (ε_Pa(Pb)W = 1.0), and strong adsorbable (ε_Pa(Pb)W = 1.2) polymer blocks. The deposition patterns are summarized into diagrams, including penetrating and nonpenetrating ridge-like structures, penetrating and nonpenetrating coffee-ring structures, and multilayer structures with and without defects. We determine factors that influence the deposition structure of the droplet and unveil the mechanism of the formation process of the pattern. This work helps in understanding the deposition pattern of linear diblock copolymer solution nanodroplets, which is beneficial for potential applications involving nanodroplet evaporation.