title: Regulation of the Deposition Morphology of Inkjet-Printed Crystalline Materials via Polydopamine Functional Coatings for Highly Uniform and Electrically Conductive Patterns.
abstract: We report a method to achieve highly uniform inkjet-printed silver nitrate (AgNO3) and a reactive silver precursor patterns on rigid and flexible substrates functionalized with polydopamine (PDA) coatings. The printed AgNO3 patterns on PDA-coated substrates (glass and polyethylene terephthalate (PET)) exhibit a narrow thickness distribution ranging between 0.9 and 1 μm in the line transverse direction and uniform deposition profiles in the line axial direction. The deposited reactive silver precursor patterns on PDA-functionalized substrates also show "dome-shaped" morphology without "edge-thickened" structure due to "coffee-stain" effect. We posit that the highly uniform functional ink deposits formed on PDA-coated substrates are attributable to the strong binding interaction between the abundant catecholamine moieties at the PDA surface and the metallic silver cations (Ag(+) or Ag(NH3)(2+)) in the solutal inks. During printing of the ink rivulet and solvent evaporation, the substrate-liquid ink (S-L) interface is enriched with the silver-based cations and a solidification at the S/L interface is induced. The preferential solidification initiated at the S-L interface is further verified by the in situ visualization of the dynamic solidification process during solvent evaporation, and results suggest an enhanced crystal nucleation and growth localized at the S-L interface on PDA functionalized substrates. This interfacial interaction mediates solute transport in the liquid phase, resulting in the controlled enrichment of solute at the S-L interface and mitigated solute precipitation in both the contact line region and the liquid ink-vapor (L-V) interface due to evaporation. This mediated transport contributes to the final uniform solid deposition for both types of ink systems. This technique provides a complementary strategy for achieving highly uniform inkjet-printed crystalline structures, and can serve as an innovative foundation for high-precision additive delivery of functional materials.
authors.affiliation: Department of Mechanical Engineering, State University of New York (SUNY) at Binghamton , Binghamton, New York 13902, United States.
authors.forename: Liang
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Mechanical Engineering, State University of New York (SUNY) at Binghamton , Binghamton, New York 13902, United States.
authors.forename: Siyuan
authors.initials: S
authors.lastname: Ma
authors.affiliation: Department of Mechanical Engineering, State University of New York (SUNY) at Binghamton , Binghamton, New York 13902, United States.
authors.forename: Yunheng
authors.initials: Y
authors.lastname: Pei
authors.affiliation: Department of Mechanical Engineering, State University of New York (SUNY) at Binghamton , Binghamton, New York 13902, United States.
authors.forename: Xiao
authors.initials: X
authors.lastname: Xiong
authors.affiliation: Department of Mechanical Engineering, State University of New York (SUNY) at Binghamton , Binghamton, New York 13902, United States.
authors.forename: Preeth
authors.initials: P
authors.lastname: Sivakumar
authors.affiliation: Department of Mechanical Engineering, State University of New York (SUNY) at Binghamton , Binghamton, New York 13902, United States.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Singler
keywords: coffee ring effect; deposition morphology control; inkjet printing; interfacial crystallization; plasma reduction; polydopamine; reactive silver ink