Deposition and Adhesion of Polydopamine on the Surfaces of Varying Wettability

Abstract

Mussel-inspired chemistry, particularly the versatile coating capability of polydopamine (PDA), has received much research interest as a promising strategy for fabricating functional coatings in numerous fields. However, the understanding of deposition mechanisms and adhesion behaviors of PDA on different substrates still remains incomplete, significantly limiting the related fundamental research and its practical applications. In this work, a colloidal probe atomic force spectroscopy technique was employed to quantify the interaction forces and adhesion between the PDA coatings and the substrate surfaces with different wettabilities. The surface force measurements and thermodynamic analysis of interaction energy indicate that the surface wettability has a significant influence on the adhesion, deposition behaviors, and morphologies of PDA coatings. Compared with the hydrophilic surfaces, the hydrophobic surfaces exhibit stronger adhesion with the PDA coatings. Furthermore, for the first time, this work demonstrates that ethanol has the capability of effectively displacing the trapped air/vapor layer or the so-called "hydrophobic depletion layer" on the hydrophobic substrate to allow the intimate contact between PDA and the substrate, thus enhancing the adhesion and facilitating the PDA deposition. This work provides new insights into the fundamental PDA deposition mechanism as well as the design and development of versatile mussel-inspired coatings on the substrates of varying hydrophobicity.

Reversible Chemo‐Topographic Control of Adhesion in Polydopamine Nanomembranes

“…PDA-NM's pH dependent high adhesion to PDMS+SiO 2 is attributed to hydrogen bonding between pendant catechols and silica, [30,31] and pH insensitive low adhesion to PDMS is attributed to hydrophobic interaction and van der Waals forces between PDA-NM and PDMS. [32,33] PDM-NM substrates at pH 10.5 exhibit no detectable adhesion to either PDMS or PDMS+SiO 2 probes with our instrumentation. Abolition of adhesion at this pH level is notable in that even hydrophobic interactivity is subdued.…”

“…Maximum pull‐off forces between PDMS+SiO 2 probes and PDA‐NM substrates at pH 4 reach up to 1.93 mN (Table S2, Supporting Information), corresponding to an equivalent work of adhesion ( W ad ) of 137 mN m −1 , according to the characteristic Johnson–Kendall–Roberts relation ( W ad = F pull /1.5 πR ; R = radius of the probe = 3 mm). PDA‐NM’s pH dependent high adhesion to PDMS+SiO 2 is attributed to hydrogen bonding between pendant catechols and silica, and pH insensitive low adhesion to PDMS is attributed to hydrophobic interaction and van der Waals forces between PDA‐NM and PDMS . PDM‐NM substrates at pH 10.5 exhibit no detectable adhesion to either PDMS or PDMS+SiO 2 probes with our instrumentation.…”

Natural phenolic compound–iron complexes: sustainable solar absorbers for wood-based solar steam generation devices

“…11 Recently, many efficient materials, including carbon materials, such as carbon nanotubes and graphene, and plasma metals, have been developed as the solar-to-thermal layer for W-SSGDs. [12][13][14][15][16][17][18][19][20][21][22][23][24] For example, Li et al 25 reported an efficient (80% under one-sun illumination) and effective (four orders salinity decrement) solar desalination device. A foldable graphene oxide lm, was served as efficient solar absorbers (>94%), vapor channels, and thermal insulators by a scalable process.…”

Development of Cu-Modified PVC and PU for Catalytic Generation of Nitric Oxide

“…By self-polymerization DA can form a very thin layer of polydopamine (pDA) (Scheme 1) capable of attaching to various surfaces [23]. pDA exhibits stronger adhesion to the hydrophobic surfaces and adheres less strongly to the hydrophilic surfaces [24]. The metal ions attach to the surface via formation of complexes with pDA quinone and catechol units [25,26].…”