Effective Surface Research Articles

Dynamic stability of the euler nanobeam subjected to inertial moving nanoparticles based on the nonlocal strain gradient theory

This research studied the dynamic stability of the Euler-Bernoulli nanobeam considering the nonlocal strain gradient theory (NSGT) and surface effects. The nanobeam rests on the Pasternak foundation and a sequence of inertial nanoparticles passes above the nanobeam continuously at a fixed velocity. Surface effects have been utilized using the Gurtin-Murdoch theory. Final governing equations have been gathered implementing the energy method and Hamilton's principle alongside NSGT. Dynamic instability regions (DIRs) are drawn in the plane of mass-velocity coordinates of nanoparticles based on the incremental harmonic balance method (IHBM). A parametric study shows the effects of NSGT parameters and Pasternak foundation constants on the nanobeam's DIRs. In addition, the results exhibit the importance of 2T-period DIRs in comparison to T-period ones. According to the results, the Winkler spring constant is more effective than the Pasternak shear constant on the DIR movement of nanobeam. So, a 4 times increase of Winkler and Pasternak constants results in 102 % and 10 % of DIR movement towards higher velocity regions, respectively. Furthermore, the effect of increasing nonlocal and material length scale parameters on the DIR movement are in the same order regarding the magnitude but opposite considering the motion direction. Unlike nonlocal parameter, an increase in material length scale parameter shifts the DIR to the more stable region.

Superhydrophobic Materials for Self-cleaning Applications: A Review

Abstract: Since the discovery of the “lotus effect,” the superhydrophobic structure of the research is more and more profound. When the droplets fall on the surface, it will not occur as a wetting phenomenon. Making full use of this feature will achieve the self-cleaning effect of the object surface. In the dust filtration problem, it is possible to spray superhydrophobic materials on the surface of the equipment using superhydrophobic self-cleaning characteristics to change the filtering method and to improve the self-cleaning efficiency. This paper describes the methods of preparing superhydrophobic materials, self-cleaning methods, and the application of superhydrophobic materials in the field of self-cleaning. Based on the summary of patents and papers, this paper focuses on the filtration and self-cleaning effect of superhydrophobic materials on dust particles in humid environments. With a simple structure, high filtration efficiency, and long service life, the super sparse/hydrophilic hybrid mesh can work continuously without manual operation. It can effectively filter dust particles and improve air quality in humid environments. Coal powder condensation experiments in this paper proved that the application of superhydrophobic materials in the field of self-cleaning yielded significant results. When superhydrophobic materials are sprayed on copper-based filters, the hydrophilic line mixes with the hydrophobic region, greatly improving the self-cleaning efficiency.

The effects of keratin-coated titanium on osteoblast function and bone regeneration

Wool derived keratin, due to its demonstrated ability to promote bone formation, has been suggested as a potential bioactive material for implant surfaces. The aim of this study was to assess the effects of keratin-coated titanium on osteoblast function in vitro and bone healing in vivo. Keratin-coated titanium surfaces were fabricated via solvent casting and molecular grafting. The effect of these surfaces on the attachment, osteogenic gene, and osteogenic protein expression of MG-63 osteoblast-like cells were quantified in vitro. The effect of these keratin-modified surfaces on bone healing over three weeks using an intraosseous calvaria defect was assessed in rodents. Keratin coating did not affect MG-63 proliferation or viability, but enhanced osteopontin, osteocalcin and bone morphogenetic expression in vitro. Histological analysis of recovered calvaria specimens showed osseous defects covered with keratin-coated titanium had a higher percentage of new bone area two weeks after implantation compared to that in defects covered with titanium alone. The keratin-coated surfaces were biocompatible and stimulated osteogenic expression in adherent MG-63 osteoblasts. Furthermore, a pilot preclinical study in rodents suggested keratin may stimulate earlier intraosseous calvaria bone healing.

New Empirical Source-Scaling Laws for Crustal Earthquakes Incorporating Fault Dip and Seismogenic-Thickness Effects

Abstract New global source-scaling relations for the aspect ratio and rupture area for crustal earthquakes that include the width-limited effect and a possible free-surface effect are derived using a global dataset of finite-fault rupture models. In contrast to the commonly used scaling relations between moment magnitude (M), fault length (L), width (W), and area, we built self-consistent scaling relations by relating M to the aspect ratio (L/W) and to the fault area to model the change in the aspect ratio once the rupture width reaches the down-dip width limit of the fault. The width-limited effect of large-magnitude earthquakes depends on the fault dip and a regional term for the seismogenic thickness. The magnitude scaling of the aspect ratio includes a break in the magnitude scaling that is dip angle dependent. This dip angle-dependent magnitude scaling in the magnitude–area relation is modeled by a trilinear relation incorporating a dip-related transition range. The effect of the free surface was observed using a normalized depth term and parameterizing the source by the depth of the top of the fault rupture; it is more apparent in the area scaling relation. The scaling differences are related to the fault geometry, not to the rake angle, as commonly assumed. Finally, the corresponding L and W scaling relations obtained by converting the area and aspect ratio models to L and W models not only show good agreement with the previous regional scaling laws on average but also provide better fault-specific application due to the inclusion of a fault-specific dip angle and seismogenic thickness.

Application and prospect of novel nanomedicine in cancer therapy

With the rapid development of nanotechnology, the application of new nanodrugs in cancer treatment has gradually become a research hotspot. In this paper, we explore the design principles, preparation methods and their anticancer effects in vitro and in vivo, and explore potential clinical applications. The results show that nanomedicine improve the therapeutic effect and reduce the side effects by achieving accurate delivery and controlled release of drugs, providing a new solution for cancer treatment. In terms of design principles, nanomdrugs mainly make use of unique properties such as small size effects, surface effects and quantum size effects of nanomaterials to combine drug molecules with nanocarriers to achieve precise delivery and controlled release of drugs. In terms of preparation methods, physical, chemical and biological methods are used to prepare nanoscale drugs with different morphology and structures. In vitro and in vivo experiments showed that nanomedicines can significantly increase the concentration of the drug in the tumor cells, enhance the therapeutic efficacy, and reduce the toxicity to normal tissues. However, nanomedicine still face many challenges in the field of cancer therapy. Looking ahead, with the continuous advances in nanotechnology, it is reasonable to believe that nanomedicine will play a greater role in the field of cancer therapy. Through in-depth study of the mechanism of action of nanomedicine, optimizing the preparation process, improving the precision of the controlled drug release system, and focusing on the biological safety issues, we are expected to bring safer and more effective treatment methods for cancer patients. At the same time, the combined application of nanomedicine and other therapeutic means such as immunotherapy and gene therapy will also become a research hotspot in the future, providing more comprehensive and personalized treatment options for cancer treatment.

Orbital-scale understanding of the surface effect of the MgCl2 in the Ziegler–Natta catalyst for ethylene polymerization: A computational study

Ziegler-Natta catalyst is a widely used olefin polymerization catalyst in petrochemical industries. However, the role of each catalyst component is not clear due to the complexity of composition and structure. MgCl2 is a suitable support for Ziegler-Natta catalyst because its crystal structure is similar to that of TiCl3, and the surface effect of MgCl2 in Ziegler-Natta catalyst system was explored in ethylene polymerization at the orbital scale. A series of the stable surface-supported catalysts with unsaturated coordination Mg2+ were used to simulate the mechanism of ethylene polymerization by the periodic density functional theory. This study found that MgCl2 with different surfaces regulates the activity of the catalyst by adjusting the d band centre of the catalyst active centre. This concept can be used to explain the surface effect of support in general catalysts.

Nature-Inspired Micro/Nano-Structured Antibacterial Surfaces.

The problem of bacterial resistance has become more and more common with improvements in health care. Worryingly, the misuse of antibiotics leads to an increase in bacterial multidrug resistance and the development of new antibiotics has virtually stalled. These challenges have prompted the need to combat bacterial infections with the use of radically different approaches. Taking lessons from the exciting properties of micro-/nano-natural-patterned surfaces, which can destroy cellular integrity, the construction of artificial surfaces to mimic natural functions provides new opportunities for the innovation and development of biomedicine. Due to the diversity of natural surfaces, functional surfaces inspired by natural surfaces have a wide range of applications in healthcare. Nature-inspired surface structures have emerged as an effective and durable strategy to prevent bacterial infection, opening a new way to alleviate the problem of bacterial drug resistance. The present situation of bactericidal and antifouling surfaces with natural and biomimetic micro-/nano-structures is briefly reviewed. In addition, these innovative nature-inspired methods are used to manufacture a variety of artificial surfaces to achieve extraordinary antibacterial properties. In particular, the physical antibacterial effect of nature-inspired surfaces and the functional mechanisms of chemical groups, small molecules, and ions are discussed, as well as the wide current and future applications of artificial biomimetic micro-/nano-surfaces. Current challenges and future development directions are also discussed at the end. In the future, controlling the use of micro-/nano-structures and their subsequent functions will lead to biomimetic surfaces offering great potential applications in biomedicine.

The surface effect of chlorinated mesoscopic TiO2 in printable carbon-based perovskite solar cells

Printable HTM-free (HTM = hole-transporting material) mesoporous carbon-based perovskite solar cells (C-PSCs) are one of the most promising technologies. In this study, a high-quality chlorinated mesoscopic TiO2 (m-TiO2) film was obtained by hydrochloric acid (HCl) wet chemical process and applied in C-PSCs based on TiO2/ZrO2/(5-AVA)x(MA)1-xPbI3/C structures. Experimental results show that the PCE of chlorinated m-TiO2 C-PSCs greatly improved. Based on (5-AVA)x(MA)1-xPbI3, C-PSCs with TiO2 ETL treated with HCl aqueous solution achieved an average photovoltaic conversion efficiency of 9.36 %, which is an increase of 7.96 % in comparison with the efficiency of the device using unmodified TiO2 ETL, while the Voc and the Jsc were increased by 3.63 % and 2.63 %, respectively. In a 30-day aging test, C-PSCs based on (5-AVA)x(MA)1-xPbI3 and TiO2-HCl 1 exhibited excellent stability under ambient air conditions.

Hybrid Fiber Influence on the Crack Permeability of Cracked Concrete Exposed to Freeze-Thaw Cycles.

This paper describes hybrid fiber's influence on the crack permeability of cracked concrete exposed to freeze-thaw cycles. A permeability setup and a laser-scanning setup have been designed to measure the crack permeability and the fractured surface roughness of cracked hybrid fiber-reinforced concrete, containing polypropylene fiber and steel fiber, under a splitting tensile load. The results show that, when the effective crack width of the specimens is less than 25 μm, the rough crack surface significantly reduces the concrete's crack permeability. As the crack width increases, the effect of the concrete crack surface on crack permeability gradually decreases, and the crack permeability of the concrete is closer to the Poiseuille flow model. The permeability parameter α derived from the Poiseuille flow model is effective for assessing the crack permeability of concrete. Compared to the modified factor ξ of crack permeability, the permeability parameter α can effectively evaluate and quantify the development trend of crack permeability within a certain range of crack widths. The permeability parameter α of SF20PP2.3, subjected to the same freeze-thaw cycles, decreases by 16.3-94.8% compared to PP4.6 and SF40, and SF20PP2.3 demonstrates a positive synergistic effect on the crack impermeability of cracked concrete. The crack impermeability of SF40PP2.3, subjected to the same freeze-thaw cycles, lies between that of PP6.9 and SF60. The roughness of crack surface (X) and the crack permeability (Y) are highly correlated and follow an exponential curve (Y = 1.0415 × 107·e-6.025·X) in concrete. This demonstrates that hybrid fibers enhance crack impermeability by increasing the crack surface roughness. Furthermore, the combination of polypropylene fiber and steel fiber effectively promotes the formation of micro-cracks and facilitates the propagation of multiple cracks in the concrete matrix. This combination increases the head loss of water flow through the concrete and decreases the crack permeability.

Translucency and Color Difference of Monolithic Zirconia Restorations: The Effect of Surface Finishing on Background Color

Aim: This study evaluates the effect of different surface finishing procedures on the color and translucency values of monolithic zirconia materials on three different colored composite backgrounds. Materials and Methods: Sixty monolithic zirconia blocks of three different translucency levels were prepared in vitro using computer-aided design/computer-aided manufacturing (CAD/CAM) systems. The correlation between repeat measurements was 0.5, resulting in a sample size of nine samples per group to detect a medium effect size, f = 0.25. Half of the zirconia blocks in each group were subjected to glazing, while the other half were polished ( n = 10). Composite blocks of three different colors were prepared to simulate dental substrates, and the zirconia specimens were placed on these composite backgrounds. The color parameters of the specimens were measured using a spectrophotometer on gray, black, and white backgrounds. Three-way repeated measure ANOVA was used to assess the interaction between the three independent variables (zirconia brand, surface finishing technique, and background color) and the effects of each tested variable on the changes in color and translucency. Results: The surface finishing techniques had a significant effect on the color and translucency of the monolithic zirconia materials. Glazing resulted in higher color differences and lower translucency values compared to polishing. For backgrounds of the same color, no significant differences were detected between the glazed zirconia groups for the same condition ( p > .016). Conclusion: Overall, the study demonstrated the importance of selecting the appropriate surface finishing technique and translucency property of the monolithic zirconia materials to obtain the optimal esthetic results in dental restorations.

Promoting CO2 Electroreduction to Ethane by Iodide-Derived Copper with the Hydrophobic Surface.

Electrochemical reduction of CO2 to value-added products provides a feasible pathway for mitigating net carbon emissions and storing renewable energy. However, the low dimerization efficiency of the absorbed CO intermediate (*CO) and the competitive hydrogen evolution reaction hinder the selective electroreduction of CO2 to ethane (C2H6) with a high energy density. Here, we designed hydrophobic iodide-derived copper electrodes (I-Cu/Nafion) for reducing CO2 to C2H6. The Faradaic efficiency of C2H6 reached 23.37% at -0.7 V vs RHE over the I-Cu/Nafion electrode in an H-type cell, which was about 1.7 times higher than that of the I-Cu electrode. The hydrophobic properties of the I-Cu/Nafion electrodes led to an increase in the local CO2 concentration and stabilized the Cu+ species. In situ Raman characterizations and density functional theory calculations indicate that the enhanced performances could be ascribed to the strong *CO adsorption and decreased the formation energy of *COOH and *COCOH intermediates. This study highlights the effect of the hydrophobic surface on Cu-based catalysts in the electroreduction of CO2 and provides a promising way to adjust the selectivity of C2 products.

Effect of surface anchoring energy on a liquid crystal optical waveguide-based polarization rotator

This study reports the effect of the surface anchoring energy of a liquid crystal (LC) cell on the performance of the liquid crystal optical waveguide polarization rotator (LCOW-PR) for the purpose of providing a theoretical reference for practical preparation of the LCOW-PR. First, the expression for the deflection angle of the director at the boundary of the LC cell is derived so that the distributions of the director and dielectric tensor of the LC can be accurately solved under any anchoring energy. On this basis, the correlation between the crucial indicators such as the polarization conversion length (PCL) together with the polarization conversion efficiency (PCE) of the LCOW-PR and the anchoring effect strength is constructed by combining with the existing numerical algorithms. The numerical results show that the maximum variation of the PCL is lower than 0.1 µm as the anchoring effect strength increases from 1×10−6J/m2 to 1×10−3J/m2, while the PCE decreases from 99.72% to 78.33%. This implies that the PCL of the LCOW-PR does not depend on the surface anchoring energy, but the anchoring effect strength of the orientational layer must be controlled to the order of 10−6J/m2 or even lower to achieve high-performance conversion between the polarization modes. Simultaneously, the effectiveness of the calculations in this work is verified with the help of the coupled mode theory as well as a comparison to previous reports.

Analytical Solutions for an Isotropic Elastic Half-Plane with Complete Surface Effects Subjected to a Concentrated/Uniform Surface Load

Analytical Solutions for an Isotropic Elastic Half-Plane with Complete Surface Effects Subjected to a Concentrated/Uniform Surface Load

Hydrothermal alteration of the surface volcanic rocks at the Acoculco geothermal field, Mexico: a multi-parametric approach

AbstractThe studies on hydrothermal alteration-induced effects in surface and subsurface rocks provide useful information in the characterization and exploitation of a geothermal reservoir. Generally, these studies are based on traditional, and reliable methods like petrography (primary and secondary minerals, and grade of alteration), and geochemistry (mobility of elements, changes in mass and concentration of elements, and fluid inclusions). Recently, apart from these established methods, some methods based on the geochemical (Chemical Index of Alteration, CIA; Weathering Index of Parkar, WIP; Loss on Ignition, LOI; and Sulfur, S) and rock magnetic properties (magnetic susceptibility, χlf; and percentage frequency-dependent susceptibility, χfd%) are also being applied in the identification of whether a rock is an altered or a fresh one. The Acoculco Geothermal Field (AGF), Mexico, is characterized by high temperature and very low permeability, and it is considered a promissory Enhanced Geothermal System. The following changes are observed in the rocks as a result of an increase in hydrothermal alteration: (1) an increase in CIA, LOI, and S values, and a decrease in WIP; (2) an increase in quartz and quartz polymorph minerals (silicification), and clay minerals (argillization); and (3) decrease in χlf values. At AGF, the most altered surface acid rocks are characterized by entirely quartz and its polymorphs, and clay minerals. The present study also indicates the applicability of the binary plots of major elements (felsic vs mafic component) and rock magnetic parameters (χlf vs. χfd%). The rock with χfd% value of 2–10 and χlf value < 0.5 × 10–6 m3 kg−1 indicate the presence of single domain and stable single domain grains, which in turn suggests that it is an altered rock. These methods are simple to apply, rapid, reliable, and have the potential to become effective tools for the identification of hydrothermally altered rocks during the initial stage of geothermal exploration.

UV-durable self-cleaning coatings for autonomous driving

A key technology to ensure the safety and accuracy of autonomous driving for future transportation is the cleanliness of the sensor surfaces for accurate signal reading. This study focuses on hydrophobic coatings with self-cleaning performances and UV durability, their possible degradation mechanism of static water contact angle (sWCA), and the effect of the hydrophobic surface on camera image quality. The UV-durable hydrophobic coatings are applied by a spray process followed by a thermal curing. The UV-durable hydrophobic coatings are evaluated on a vision camera under lab-simulated weathering conditions such as rain, mud, fog, and bugs, on samples as-prepared and after various hours of Weather-Ometer® weathering. The results indicate that the sWCA degradation of the UV-durable hydrophobic coatings during accelerated weathering is corresponding to the loss of fluorine (F) atomic percentage in the coatings, and the vision camera imaging quality improves significantly with the UV-durable hydrophobic coatings in comparison to an uncoated surface. The self-cleaning performances of the UV-durable hydrophobic coatings, as measured by two metrics using signal-to-noise ratio and modulation transfer function 50 loss (MTF50loss), linearly correlate with sWCA of the coatings. The UV-durable hydrophobic coatings on the sensor surface will significantly benefit autonomous driving specifically for accurate signal reading under inclement weather.

Engineering Highly Emissive Tetra(t‐Butyl)rubrene/off‐Stoichiometry Thiol‐Ene Hybrids Toward Flexible Luminescent Solar Concentrator‐Integrated Photovoltaics with Excellent Stability

Luminescent solar concentrators (LSCs) are highly valued in transparent photovoltaics for their versatility and adaptability as effective large‐area sunlight collectors. However, constructing LSCs as efficient, long‐term stable, and easily malleable power‐generating units still remains a challenge. Herein, high photostability, high photoluminescence quantum yield (ΦPL), and Stokes‐shifted emission are achieved in tetra(t‐butyl)rubrene/off‐stoichiometry thiol‐ene (TBRb/OSTE) hybrids by incorporating TBRb molecules into OSTE polymers. To demonstrate their potentials in LSCs, a luminescent solar concentrator integrated photovoltaics (LSCIPV) is created using a one‐step synthesis that combines the preparation of TBRb/OSTE hybrids, coupling with the silicon solar cell, and the encapsulation of both components. The LSCIPV demonstrates remarkable flexibility and the integration of an ethylene tetrafluoroethylene film contributes to a hydrophobic surface and antireflection effect, resulting in an external photon efficiency (ηext) of 4.9% and a power conversion efficiency of 1.04% for the 100 cm2 device. The LSCIPV exhibits good photostability over 800 h of UV light exposure. Monte Carlo ray‐tracing simulations indicate that an optimized TBRb‐based LSCIPV can potentially achieve an ηext of 1.3%, even for a large device with an area of 1 m2.

Revealing the mechanism of combining best properties of homogeneous and heterogeneous catalysis in hybrid Pd/NHC systems

The formation of transient hybrid nanoscale metal species from homogeneous molecular precatalysts has been demonstrated by in situ NMR studies of catalytic reactions involving transition metals with N‐heterocyclic carbene ligands (M/NHC). These hybrid structures provide benefits of both molecular complexes and nanoparticles, enhancing the activity, selectivity, flexibility, and regulation of active species. However, they are challenging to identify experimentally due to the unsuitability of standard methods used for homogeneous or heterogeneous catalysis. Utilizing a sophisticated solid‐state NMR technique, we provide evidence for the formation of NHC‐ligated catalytically active Pd nanoparticles (PdNPs) from Pd/NHC complexes during catalysis. The coordination of NHCs via C(NHC)‐Pd bonding to the metal surface was first confirmed by observing the Knight shift in the 13C NMR spectrum of the frozen reaction mixture. Computational modeling revealed that as little as few NHC ligands are sufficient for complete ligation of the surface of the formed PdNPs. Catalytic experiments combined with in situ NMR studies confirmed the significant effect of surface covalently bound NHC ligands on the catalytic properties of the PdNPs formed by decomposition of the Pd/NHC complexes. This observation shows the crucial influence of NHC ligands on the activity and stability of nanoparticulate catalytic systems.

Revealing the mechanism of combining best properties of homogeneous and heterogeneous catalysis in hybrid Pd/NHC systems.

The formation of transient hybrid nanoscale metal species from homogeneous molecular precatalysts has been demonstrated by in situ NMR studies of catalytic reactions involving transition metals with N-heterocyclic carbene ligands (M/NHC). These hybrid structures provide benefits of both molecular complexes and nanoparticles, enhancing the activity, selectivity, flexibility, and regulation of active species. However, they are challenging to identify experimentally due to the unsuitability of standard methods used for homogeneous or heterogeneous catalysis. Utilizing a sophisticated solid-state NMR technique, we provide evidence for the formation of NHC-ligated catalytically active Pd nanoparticles (PdNPs) from Pd/NHC complexes during catalysis. The coordination of NHCs via C(NHC)-Pd bonding to the metal surface was first confirmed by observing the Knight shift in the 13C NMR spectrum of the frozen reaction mixture. Computational modeling revealed that as little as few NHC ligands are sufficient for complete ligation of the surface of the formed PdNPs. Catalytic experiments combined with in situ NMR studies confirmed the significant effect of surface covalently bound NHC ligands on the catalytic properties of the PdNPs formed by decomposition of the Pd/NHC complexes. This observation shows the crucial influence of NHC ligands on the activity and stability of nanoparticulate catalytic systems.

Exploiting Saturation Regimes and Surface Effects to Tune Composite Design: Single Platelet Nanocomposites of Peptoid Nanosheets and CaCO3.

Mineral-polymer composites found in nature exhibit exceptional structural properties essential to their function, and transferring these attributes to the synthetic design of functional materials holds promise across various sectors. Biomimetic fabrication of nanocomposites introduces new pathways for advanced material design and explores biomineralization strategies. This study presents a novel approach for producing single platelet nanocomposites composed of CaCO3 and biomimetic peptoid (N-substituted glycines) polymers, akin to the bricks found in the brick-and-mortar structure of nacre, the inner layer of certain mollusc shells. The significant aspect of the proposed strategy is the use of organic peptoid nanosheets as the scaffolds for brick formation, along with their controlled mineralization in solution. Here, we employ the B28 peptoid nanosheet as a scaffold, which readily forms free-floating zwitterionic bilayers in aqueous solution. The peptoid nanosheets were mineralized under consistent initial conditions (σcalcite = 1.2, pH 9.00), with variations in mixing conditions and supersaturation profiles over time aimed at controlling the final product. Nanosheets were mineralized in both feedback control experiments, where supersaturation was continuously replenished by titrant addition and in batch experiments without a feedback loop. Complete coverage of the nanosheet surface by amorphous calcium carbonate was achieved under specific conditions with feedback control mineralization, whereas vaterite was the primary CaCO3 phase observed after batch experiments. Thermodynamic calculations suggest that time-dependent supersaturation profiles as well as the spatial distribution of supersaturation are effective controls for tuning the mineralization extent and product. We anticipate that the control strategies outlined in this work can serve as a foundation for the advanced and scalable fabrication of nanocomposites as building blocks for nacre-mimetic and functional materials.

Polydopamine films: Versatile but interface-dependent coatings

Abstract Polydopamine coatings have been shown to allow to coat almost all materials with conformal films having a tunable thickness from a few up to more than 100 nm (and even more in some specific cases). These films are able to reduce metal cations, to be modified with many chemical moieties and advent hence as a “Holy Grail” in surface chemistry with an impressive amount of applicative papers published since 2007. However, the broad application field and ease of deposition from aqueous solutions hidden the complexity of the deposition mechanism(s). The discovery that polydopamine (PDA) films also form at air/water interfaces (in the absence of stirring or in stirring dependent manner) to yield membranes with physicochemical properties different than PDA films deposited at solid/water interfaces highlighted for the first time that the nature of the interfaces plays a major role in the PDA film growth mechanism and in the film properties. More recent research allowed to show that the surface chemistry of the used solid substrate modifies the composition of the thin deposited PDA film during the early stages of the deposition process with further deposition yielding to an almost substrate-independent PDA film. It is the aim of this review to describe complex surface effects occurring in PDA deposition and hence to complement other reviews which described the complexity of the chemistry yielding to PDA coatings.