Laser-induced graphitization of polydopamine leads to enhanced mechanical performance while preserving multifunctionality

Abstract

Polydopamine (PDA) is a simple and versatile conformal coating material that has been proposed for a variety of uses; however in practice its performance is often hindered by poor mechanical properties and high roughness. Here, we show that blue-diode laser annealing dramatically improves mechanical performance and reduces roughness of PDA coatings. Laser-annealed PDA (LAPDA) was shown to be >100-fold more scratch resistant than pristine PDA and even better than hard inorganic substrates, which we attribute to partial graphitization and covalent coupling between PDA subunits during annealing. Moreover, laser annealing provides these benefits while preserving other attractive properties of PDA, as demonstrated by the superior biofouling resistance of antifouling polymer-grafted LAPDA compared to PDA modified with the same polymer. Our work suggests that laser annealing may allow the use of PDA in mechanically demanding applications previously considered inaccessible, without sacrificing the functional versatility that is so characteristic of PDA.

Bio-Applications of Multifunctional Melanin Nanoparticles: From Nanomedicine to Nanocosmetics

“…Recently, Messersmith and coworkers demonstrated that, indeed, having both catechols and amines combined in the same functional monomer is advantageous for the final adhesion strength: decoupling the two kinds of functional groups, in fact, prevents cooperative effects with an observable worsening of the adhesive performances [ 89 ]. The same author also showed that mechanical properties of PDA coating can be further enhanced, and the roughness reduced, by treatment with blue-diode laser treatment, inducing graphitization while preserving multifunctionality [ 90 ]. Surface adhesion of PDA and related materials have been investigated in detail also by Lee and coworkers [ 91 ], who demonstrated that the stability of the obtained coatings is widely independent on the chemical composition of the surface itself [ 92 ].…”

New insights in polydopamine formation via surface adsorption

“…The same chemical species as observed in the C1s spectrum of PDA-A (see Supplementary Fig. 6b) can be identified in the C1s spectra of HNT-PDA samples, namely C-C/C=C (red, observed at a binding energy (BE) of 284.8 eV), C-O/C-N (blue, BE=286.1 eV), C=O/C=N (green, BE=287.5 eV), O=C-O (pink, BE=289.2 eV) bonds and shake-up component at BE of 291.3 eV 18,30,31 . The spectrum of the N1s core level region changes significantly as the polymerization proceeds (see Fig.…”

The Photophysics and Photochemistry of Melanin‐ Like Nanomaterials Depend on Morphology and Structure

“…a) Atomic force microscopy (AFM) images with line-scan profiles, optical microscope images and SEM images of a pristine PDA at 1.9 W and b) AFM images with line-scan profiles, optical microscope images and SEM images of laser-annealed PDA at 1.9 W. Reprinted with permission from Ref. [32]. Copyright 2020, Nature portfolio.…”

“…[7c], [13], [18], [21b], [22], [24], [32], [50g] Films [19], [32] fluorescence induced in these materials is fundamental. In particular, in the case of melanin NP it has not been definitively demonstrated whether the fluorescence comes from the NP themselves or from molecular residuals produced during the treatments applied in order to produce emission.…”