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The evaporation-induced deposition pattern of the linear diblock copolymer solution has attracted attention in recent years. Given its critical applications, we study deposition patterns of the linear diblock copolymer solution nanodroplet on a solid surface (the wall) by molecular dynamics simulations. This study focuses on the influence of the nonbonded interaction strength, including the interaction between the wall and polymer blocks (ɛAW and ɛBW), the interaction between the solvent and the wall (ɛSW), and the interaction between polymer blocks (ɛAB). Conditions leading to diverse deposition patterns are explored, including the coffee-ring and the volcano-like structures. The formation of the coffee-ring structure is attributed to receding interfaces, the heterogeneity inside the droplet, and the self-assembly of polymer chains. This study contributes to the establishment of guidelines for designing deposition patterns of the linear diblock copolymer solution nanodroplet, which facilitates practical applications such as inkjet printing. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were used to analyze the mechanical properties and failure processes of poly(p-phenylene-terephthalamide) (PPTA), poly(p-phenylene-benzimidazole-terephthalamide) (PBIA), PBIA–PPTA (formed by 1:1 copolymerization of PPTA and PBIA), and poly(p-phenylene-benzobisoxazole) (PBO) crystals at different strain rates and temperatures. The failure stress and strain were found to be linear with the temperature and logarithmic strain rate. Moreover, based on the kinetic theory of fracture and the comprehensive simulation results, we formulated a model that describes the failure stress of the aforementioned crystals under varying strain rates and temperatures. Through the analysis of the failure process, we found that in PPTA, PBIA, and PBIA–PPTA crystals, the bond failure probability is correlated with the strain rate and temperature. The examination of bond lengths and angles unveiled that bonds with larger initial aligning angles are more susceptible to failure during the strain process. Intriguingly, the stretching process induced a conformational change in the PBO molecular chain, leading to a deviation from the linear relation in its stress–strain curve. [ABSTRACT FROM AUTHOR]

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 (εPa(Pb)W) are modified to simulate polymer blocks with different adsorption behaviors, such as weak adsorbable (εPa(Pb)W = 0.6), moderate adsorbable (εPa(Pb)W = 1.0), and strong adsorbable (εPa(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. [ABSTRACT FROM AUTHOR]

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.