Homogeneous Thickness Research Articles

Low-Cost Pipetting Robot Based on a Portal Milling Machine

Chemical adhesion promoters are necessary for the production of long-term stable metal-rubber composites. After these have been applied, rubber is molded onto the metallic base bodies by rubber injection molding. In (very) small batches, the adhesion promoter can be applied in precise volumes by hand using a fluid dispenser. However, this prevents homogeneity and uniformity of the layer thickness, which can cause variation in the reliability and strength of adhesion. As a technical solution, a pipetting robot has been envisaged. With the aid of several mechanical and electrical adaptations - including a new control technology - various fluid dispensers were integrated on 3-axis portal milling machines. Thus, full functionality could be achieved.

Uniform thin ice on ultraflat graphene for high-resolution cryo-EM

Cryo-electron microscopy (cryo-EM) visualizes the atomic structure of macromolecules that are embedded in vitrified thin ice at their close-to-native state. However, the homogeneity of ice thickness, a key factor to ensure high image quality, is poorly controlled during specimen preparation and has become one of the main challenges for high-resolution cryo-EM. Here we found that the uniformity of thin ice relies on the surface flatness of the supporting film, and developed a method to use ultraflat graphene (UFG) as the support for cryo-EM specimen preparation to achieve better control of vitreous ice thickness. We show that the uniform thin ice on UFG improves the image quality of vitrified specimens. Using such a method we successfully determined the three-dimensional structures of hemoglobin (64 kDa), α-fetoprotein (67 kDa) with no symmetry, and streptavidin (52 kDa) at a resolution of 3.5 Å, 2.6 Å and 2.2 Å, respectively. Furthermore, our results demonstrate the potential of UFG for the fields of cryo-electron tomography and structure-based drug discovery.

Microstructural Evaluation of Graphene-Reinforced Nickel Matrix Ni-P-Gr Coating on Ti-6Al-4V Alloy by the Electroless Coating Method

Titanium alloys are widely used in many industrial applications, from aerospace to automotive, and from defense to medical, as they combine superior properties such as high strength and low density. Still, titanium and its alloys are insufficient in environments with friction and wear because of their weak tribological properties. In the literature, numerous research works on improving the surface quality of titanium alloys have been conducted. Electroless coatings, on the other hand, are one of the most widely used surface improvement methods due to its homogeneous thickness achievement, high hardness, and good corrosion resistance. The autocatalytic reduction in the coating process enhances the surface quality of the material or alloy considerably. In addition, many studies in the literature aim to carry the properties of electroless coatings to a higher point by creating a composite coating with the addition of extra particles. In this study, graphene-reinforced nickel matrix Ni-P-Gr coating was applied to the surface of Ti-6Al-4V alloy, in order to enhance weak tribological behaviors, by the electroless coating method. Moreover, the coated and uncoated, heat-treated, and non-heat-treated specimens were subjected to abrasion in linear reciprocating ball-on-plate configuration to observe tribological properties. Microstructure examination of the samples was performed using a scanning Electron Microscope (SEM), X-ray Diffractometer (XRD), X-ray Photon Spectrometry (XPS), and Raman Spectroscopy. Specific wear rates of specimens were calculated using microstructural analysis and the hardness of the produced samples was measured using the Vickers hardness test. Results indicate that both the coating and the heat treatment improved the microstructure and tribological properties significantly. With the graphene-reinforced Ni-P coating via electroless coating process, the hardness of the substrate increased by about 34%, while it increased by approximately 73% using subjected heat treatment. Furthermore, the wear rate of the Ti-6Al-4V substrate was approximately 98% higher than that of the heat-treated nanocomposite coating. The highest wear resistance was obtained at the heat-treated nanocomposite coating.

Modelling of heat and mass transfer in clothing considering evaporation, condensation, and wet conduction with case study

Over the past few decades, several models of heat and mass transfer have been based on the assumption of the homogeneous thickness (or absence) of the enclosed air layer contradicting the real-life scenario of the skin-clothing-environment system. To address this research gap, in this study, the comprehensive model for heat and mass transfer was developed which considers thermal phenomena such as evaporation, condensation, and the effect of liquid moisture on the thermal insulation of fabrics (wet conduction) along with sensible heat transfer mechanisms and effects of spatial heterogeneity of air layers. The coupling between heat and mass transfer in the modelling approach resulted in an accurate evaluation of the mass of evaporated liquid moisture and condensed water vapour in a skin-clothing-environment system. The developed model is systematically validated with an increasing level of spatial complexity using homogeneous and heterogeneous air layers with single-layer and multi-layer clothing ensembles. The model is validated for 21 different experimental cases covering various parameters that affect mass transfer such as enclosed air gap thickness (clothing fit), evaporative resistance (permeable, semi-permeable, and impermeable to water vapour), ambient temperature (−10 °C to 34 °C), and relative humidity (80% to 18.5%). Finally, the relevance of the model for product development is demonstrated by a case study about smart skiwear. The presented study provides detailed insights into individual heat and mass transfer mechanisms in the skin-clothing-environment system, which is very useful to develop an in-depth understanding about local heat transfer mechanisms and for designing and development of functional and protective clothing.

The impact of thickness heterogeneity on soft tissue biomechanics: a novel measurement technique and a demonstration on heart valve tissue.

The mechanical properties of soft tissues are driven by their complex, heterogeneous composition and structure. Interestingly, studies of soft tissue biomechanics often ignore spatial heterogeneity. In our work, we are therefore interested in exploring the impact of tissue heterogeneity on the mechanical properties of soft tissues. Therein, we specifically focus on soft tissue heterogeneity arising from spatially varying thickness. To this end, our first goal is to develop a non-destructive measurement technique that has a high spatial resolution, provides continuous thickness maps, and is fast. Our secondary goal is to demonstrate that including spatial variation in thickness is important to the accuracy of biomechanical analyses. To this end, we use mitral valve leaflet tissue as our model system. To attain our first goal, we identify a soft tissue-specific contrast protocol that enables thickness measurements using a Keyence profilometer. We also show that this protocol does not affect our tissues' mechanical properties. To attain our second goal, we conduct virtual biaxial, bending, and buckling tests on our model tissue both ignoring and considering spatial variation in thickness. Thereby, we show that the assumption of average, homogeneous thickness distributions significantly alters the results of biomechanical analyses when compared to including true, spatially varying thickness distributions. In conclusion, our work provides a novel measurement technique that can capture continuous thickness maps non-invasively, at high resolution, and in a short time. Our work also demonstrates the importance of including heterogeneous thickness in biomechanical analyses of soft tissues.

Role of surface morphology on bed material activation during indirect gasification of wood

Olivine and alkali-feldspar were utilized in separate campaigns in an indirect dual fluidized bed gasification campaign with woody biomass as fuel. After three days, both bed materials were reported to be active towards tar removal and exhibited oxygen-carrying abilities and had formed an ash layer consisting of an outer ash deposition layer and an inner interaction layer.X-ray microtomography analysis concluded that a preferred deposition of ash happens onto convex regions of the bed particles, which results in an increase in thickness of the ash layer over convex regions. This effect is most pronounced for the outer layer which is a product of ash deposition. The inner layer exhibits a homogeneous thickness and is probably formed by interaction of Ca from the outer layer with the particles. Transmission electron microscopy revealed the presence of Fe and Mn on the surface of the particles in a solid solution with Mg. The oxygen-carrying effect which is found for aged particles is therefore attributed to the presence of Fe and Mn on the surface of aged particles. Alkali were found on the surface of both particles which are likely contributing to the catalytic activity of the material towards tar removal.

Integration Aspects of Plasmonic TiN-based Nano-Hole-Arrays on Ge Photodetectorsin a 200mm Wafer CMOS Compatible Silicon Technology

During the last decade optical sensor technologies have attracted increased attention for various applications. Plasmon-based optical sensor concepts for the detection of refractive index changes that rely on propagating surface-plasmon polaritons at metal-dielectric interfaces or on localized plasmons in metallic nanostructures prove their potential for these application due to their fast detection speed, high specificity and sensitivities [1, 2]. Combining plasmonic structures directly with optoelectronic devices could enable a high level of integration, however, it represents a significant technological challenge to develop an on-chip solution for these concepts including the integration of sensor and detector components. Previous works demonstrated first approaches mainly for the integration of refractive index sensor components on wafer level [3, 4]. In [5] and [6] a proof-of-concept of a fully integrated on-chip solution with high sensitivities was presented, which can be easily combined with microfluidics [7] for potential applications in biosensing. In this concept, a nanohole array (NHA) was structured in a 100 nm thick aluminum layer on top of a vertical PIN germanium photodetector (GePD) with an intrinsic germanium sheet of 480 nm. This sensor concept relies on extraordinary optical transmission through the NHA [8]: Light transmission is only possible for narrow wavelength ranges determined by the NHA geometry which determine the transmission peaks at the resonance wavelength of the NHA. Thus, the NHA acts as a high quality wavelength filter. Due to the change in the refractive index, a material under test (MUT) contacting directly the surface of the NHA, provokes a shift of the wavelength maximum, which can be detected by measuring the photocurrent spectra of the GePD. While responsivities and sensitivities of (0 V) = 0.075 A/W and = 1200 nm/RIU could be attained in this proof-of-concept device [6, 7], the semiconductor device layers were deposited using molecular beam epitaxy (MBE). Furthermore the vertical PIN GePD was realized by a mesa procedure to enable large areas for top illuminated operations. These techniques are unsuitable for an industrial CMOS fabrication process with high throughput. Therefore, the development of a CMOS compatible technology process with low costs and high yields is an important step towards large-scale fabrication of this sensor concept.In this work we present the progress for the realization of a surface plasmon resonance (SPR) refractive index sensor in a 200 mm wafer Silicon based technology. One main challenge is the fabrication of a large area photodetector for top illuminated sensor devices. We developed a process, which is mainly based on the IHP electronic photonic integrated circuits (ePIC) technology [9]. This ePIC technology enables the production of waveguide coupled lateral PIN GePDs with high bandwidth and high responsivities [10]. However, these PDs are unsuitable for top illuminated applications because of their small germanium areas. Due to certain process conditions with respect to chemical mechanical polishing procedures there are limits for feasible large detector areas. Furthermore, large detector areas for lateral PIN GePDs would result in very low electric fields in the intrinsic zone where carriers are generated by photon absorption. Thus, very high voltages for reversed bias are necessary for sufficient carrier drifts.For the first time we have developed a modern detector design concept which is compatible to the IHP ePIC technology. This concept allows the realization of large area detectors of 1600µm² (40µm x 40µm) with optimized optical responsivities for top illuminated applications. The detector consists of several parallel connected lateral PIN GePDs. We designed different variations and varied Ge width and distance between neighboring GePDs in order to investigate process limits. The p- and n-doped regions were defined by dopant implantation using a photo resist mask. We used a finger-like design as implantation masks to enable one contact area for each p-doped and each n-doped region (Fig. 1). This contacting approach differs from the standard GePD offered in the IHP ePIC technology. We analyzed I-V characteristics in dependence of detector design and contacting scheme (Fig. 2). In addition, process adjustments for the optimization of the germanium quality were investigated to reduce dark currents and to improve optical responsivities (Fig.3).Titanium nitride (TiN) is very promising metallic alloy with respect to thickness homogeneity and low surface roughness. Therefore we used titanium nitride which was deposited by a sputtering process to develop plasmonic active NHA layers. Various process development runs were done to evaluate the NHA performance. Ellipsometry and atomic force microscope measurements were performed to characterize the quality of the TiN layer (Fig.4). Figure 1

Ultrathin Cage‐based Covalent Organic Framework Nanosheets as Precursor for Pyrolysis‐Free Oxygen Evolution Reaction Electrocatalyst

AbstractUltrathin covalent organic framework (COF) nanosheets are very appealing 2D materials, but the mass production of ultrathin COF nanosheets remains a great challenge. Here, by using cage‐like bicyclocalix[2]arene[2]triazines tri‐aldehyde (BCTAL) as the building block, 2D COF Cage‐COF‐1 was estimated to have a very weak interaction between adjacent layers (around 1/50 compared to that of graphite). As a result, 1.2 nm thick trilayer COF nanosheets were facilely exfoliated from the pristine COFs with large lateral size and high thickness homogeneity. The Cage‐COF‐1 nanosheet is featured by imine linkage, but it is catalytic inactive in oxygen evolution reaction (OER). After post‐metalation with Co2+ under ambient conditions, remarkable catalysis activity and stability was observed for Cage‐COF‐1‐Ns/Co, which has lower overpotential (330 mV) and Tafel slope (56 mV/dec) in catalytic OER compared to many other Co catalysts. This work has confirmed that weakening the interlaminar interaction is an effective strategy for the production of ultra‐thin COFs nanosheets. Due to the fully exposed and accessible imine linkage, catalysis active metal site can be controllably produced via post‐synthesis from nanosheets under very mild conditions.

Autologous or bovine pericardium for aortic cusp replacement? Histomorphological and biomechanical properties as decision making tools

Abstract Background/Introduction Aortic valve cusp replacement using autologous pericardium is a promising technique. Expected advantages are reduced immune response, proper biomechanics and lower treatment expenses. During surgery decision for preferred pericardium segment is based on visual criteria. Autologous pericardium can be affected by patient's condition and age. Bovine pericardium, also the basic material for aortic valve prostheses, is easy available and carefully pre-examined. In this study, the homogeneity of tissue thickness, elastic modulus, vessel density and ECM components of GA-treated residual pericardia after surgery is compared with bovine pericardia equivalently treated. Purpose Aim of the study is the comparison of homogeneity of remaining autologous pericardium after surgical aortic valve replacement with bovine pericardia to evaluate and classify the individual applicability. Methods Up to 12 samples of human (n=7) or bovine (n=3) pericardia were analysed. Tissues were treated with 0.6% glutaraldehyde according to surgical protocol. Picrosiriusred- and HE-staining were performed (three edges per separated leaflet). Vessel or collagen content was determined with Zen Blue resp. Fiji software (colour deconvolution plugin, user threshold values). Sample thickness was measured via thickness gauge FD50 before uniaxial tensile testing. Hydroxyproline content was determined and related to dry weight. T-Test or ANOVA were used to test inter-species or intra-individual differences, respectively. Results Human pericardia contain with 64.66±3.85% less collagenous fibres compared to bovine pericardia (86.01±1.713%); their vessel density is with 29.46±3.73 mm–2 significantly higher than in bovine samples (12.34±1.636 mm–2). In addition, human pericardia are with 367.7±59.2 μm significantly thinner than bovine (524.4±96.8 μm). Tensile testing (human: 36.00±15.17 MPa; bovine: 41.30±7.767 MPa) also revealed significant differences. With 77.80±11.76 mg/g merely a trend was observed for a lower hydroxyproline content in human samples (bovine 93.16±5.130 mg/g). ANOVA analyses of human pericardia illustrate significant differences for all properties, thus thickness, elastic modulus and hydroxyproline and collagen content between the individual human pericardium samples. In contrast, bovine pericardia showed an intra-individual difference only for the parameter of tissue thickness. Conclusion Human and bovine pericardia differ in histological and biomechanical parameters. In contrast to bovine pericardia, individual human pericardia were significantly different in most parameters investigated, leading to the conclusion that autologous materials are critically more heterogeneous than xenogeneic tissues. Vessel density in human pericardium was twofold higher than in bovine pericardia and can result in a higher risk for calcification. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): TU Dresden

Chemical Vapor Deposition of Longitudinal Homogeneous Parylene Thin-Films inside Narrow Tubes

The effect of quasi-exponentially decreasing film thicknesses of thin poly-para-xylylene (PPX-N) coatings inside narrow tubes or micro scaled gaps is well known and has been discussed by many authors since the late 1970s. However, for technical applications it is often necessary to provide a longitudinal homogeneous film thickness to ensure the constant properties that are required. In a previous work, it was shown, in principle and for the first time, that a temperature gradient along the tube will effectively counteract the longitudinal decreasing film thickness of the PPX-N coating of the interior wall of a capillary. Therefore, this effect is discussed in theory and the provided model is verified by experiments. Our prediction of a required sticking coefficient curve yields experimentally measured homogeneous film thicknesses and shows a good agreement with the given prognosis. Further, it is shown in theory that there is a maximum achievable homogeneous film thickness in the tube in comparison to a blank surface, which can be understood as a coating efficiency for this type of deposition.

Tailoring Titanium Sheet Metal Using Laser Metal Deposition to Improve Room Temperature Single-Point Incremental Forming.

Typically, due to their limited formability, elevated temperatures are required in order to achieve complex shapes in titanium alloys. However, there are opportunities for forming such alloys at room temperature using incremental forming processes such as single-point incremental forming (SPIF). SPIF is an innovative metal forming technology which uses a single tool to form sheet parts in place of dedicated dies. SPIFs ability to increase the forming limits of difficult-to-form materials offers an alternative to high temperature processing of titanium. However, sheet thinning during SPIF may encourage the early onset of fracture, compromising in-service performance. An additive step prior to SPIF has been examined to tailor the initial sheet thickness to achieve a homogeneous thickness distribution in the final part. In the present research, laser metal deposition (LMD) was used to locally thicken a commercially pure titanium grade 2 (CP-Ti50A) sheet. Tensile testing was used to examine the mechanical behaviour of the tailored material. In addition, in-situ digital image correlation was used to measure the strain distribution across the surface of the tailored material. The work found that following deposition, isotropic mechanical properties were obtained within the sheet plane in contrast to the anisotropic properties of the as-received material and build height appeared to have little influence on strength. Microstructural analysis showed a change to the material in response to the LMD added thickness, with a heat affected zone (HAZ) at the interface between the added LMD layer and non-transformed substrate material. Grain growth and intragranular misorientation in the added LMD material was observed. SPIF of a LMD tailored preform resulted in improved thickness homogeneity across the formed part, with the downside of early fracture in a high wall angle section of the sheet.

In-situ synthesized MgO-based ceramic coatings on a novel Mg–Ca material: Morphological response to the PEO electrolyte

MgO-based ceramic layers were in-situ synthesized on a novel Mg-based substrate via plasma electrolytic oxidation (PEO). The effects of electrolyte composition on the morphology of the layers were investigated through preparing three different ion arrangements, including common silicate-based and phosphate-based electrolytes as well as a modified Ca-containing phosphate-based electrolyte. Characterization methods including scanning electron microscopy and EDS elemental analysis were used to investigate the morphological features of the coatings, at the surfaces and cross-sections. Results indicated that the silicate-based electrolyte yields morphologically inhomogeneous coating with small porosities, while using the phosphate-based electrolytes may result in improved thickness and modified porosities. However, both of the coatings prepared via common electrolytes present Ca-containing heterogeneities, called nuggets. Using the modified phosphate-based electrolyte, it was indicated that the addition of Ca2+ ions not only removes any elemental/morphological heterogeneities in the PEO coating but also provides a ceramic layer with homogenous thickness distribution. However, it was confirmed that the PEO conditions should be changed to obtain the optimum morphological characteristics in coatings synthesized via Ca-contained electrolyte.

New Ceramic Multi-Unit Dental Abutments with an Antimicrobial Glassy Coating.

The choice of suitable materials and new designs in oral implantology and the subsequent enhancement of the characteristics of the dental implant developed is an important research topic with wide scope. The present work aims to develop a new multifunctional zirconia–ceria/alumina (Ce–TZP/Al2O3) composite with an antimicrobial glass-based coating to be used in multi-unit abutments compatible with commercially available Ti implants for peri-implantitis prevention. An airbrush spraying technique was effectively applied to coat the sintered ceramic composite starting from a glass powder suspension. This deposition technique was appropriate for obtaining continuous antimicrobial glass-based coatings with homogenous thickness (~35 µm) on ceramic dental implant components. The dental implant systems with the antimicrobial glassy coating were subjected to a mechanical integrity test following ISO 14801 to determine their long-term stability. The tested implant-coating structure seems to be stable under in vitro conditions with ultimate applied forces exceeding the maximum physiological occlusal loading force. This paper also presents a pilot clinical case report that shows peri-implant tissue around the mechanically stable glass coating with no signs of inflammation 1 year after implant insertion. This result is a preliminary probe of the durability and biological tolerance of the glassy material by the gingiva, as well as the antimicrobial effect on the peri-implant microbiota displayed by the coating.

Improvement of incremental sheet metal forming with the help of a pressurised fluid system

Abstract The single point incremental sheet forming process is a flexible manufacturing process to produce complex three-dimensional products. Unlike traditional forming processes, the single point incremental sheet forming process does not require unique tools or die. This method is constantly being improved to increase the uniform formability of the material. The fluid assisted single point incremental sheet metal forming process with a newly developed system was experimentally investigated in this research. A controlled pressure fluid was applied to the forming surface in the opposite direction during shaping. Shaping processes were carried out using different fluid pressure values. The effect of this pressurised system on the forming quality was investigated by considering material wall thickness changes, heat generation and surface roughness. The results were compared with the results obtained with the traditional single point incremental sheet forming method. It has been determined that our method increases the formability of the finished product and shows a homogeneous thickness distribution.

Numerical modeling of the crystallization process in liquid phase epitaxial growth of silicon

Numerical modeling is applied to investigate the liquid phase epitaxial growth of silicon from tin-silicon solutions in a “sandwich” cell system. The model is based on physical and numerical approaches which allow for transient computations of the solid-liquid interface shape during the crystallization process. Numerical simulations consider the thermo-solutal convection and the dependence of the solidification temperature on the liquid composition. Numerical results show that the top epitaxial layer grows faster and exhibits a wavier surface as compared to the bottom layer. The predicted layers thickness, solid-liquid interfaces shape and the growth rates are in agreement with the experimental observations. The influence of the cooling rate on the deposited layers thickness and smoothness was investigated at different liquid heights. It is found that the growth from wide liquid solutions (8 mm) at high cooling rates (2°C/min) is favorable for the deposition of thick Si layers of homogeneous thickness.

Mechanically Contacted Distributed-Feedback Optical Microcavity.

We report a construction of distributed-feedback (DFB) optical microcavities, which is realized through mechanical contact between a high-quality planar thin film of a polymeric semiconductor and a large-area homogeneous nanograting. Using poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3] thiadiazol-4,8-diyl)] (F8BT) as the active medium for the planar layer, we achieve strong amplified spontaneous emission from such a microcavity with a low threshold. This not only simplifies largely the fabrication techniques for DFB microcavities, but also avoids the unexpected chemical interactions during solution processing between the organic semiconductors and the nanograting materials. Furthermore, high-quality polymer thin films with high surface smoothness and high thickness homogeneity are employed without any modulations for constructing the microcavities. This also suggests new designs of microcavity light-emitting diodes, or even for realizing electrically pumped polymer lasers, simply by metallizing the dielectric nanogratings as the electrodes.

Development of system to grow ZnO films by plasma assisted reactive evaporation with improved thickness homogeneity for using in solar cells

This paper focuses on the development and evaluation of an automated system for the deposition of ZnO thin films with suitable properties to be used in solar cells, using the plasma assisted reactive evaporation (PARE) method. A description is made of both the electronic system developed and the Zn evaporation source implemented with a novel design based on the effusion cell concept. This development made it possible to significantly improve both the low reproducibility of the optoelectric properties and the inhomogeneity of the thickness of the ZnO films that were deposited using a previous version of the PARE system developed.The improvement of thickness homogeneity and the applicability of the ZnO thin films for use in solar cells was verified through measurements of the thickness, spectral transmittance and electrical resistivity of samples deposited on 5 × 4 cm2 glass substrates. By optimizing the preparation parameters, it was possible to deposit thin ZnO films with improved thickness homogeneity, characterized by having resistivities varying between 9.5 × 10−4 Ωcm (n+-ZnO) and 2 × 104 Ωcm (i-ZnO) and transmittances greater than 85% (in the visible region). The structural, optical and morphological properties of the ZnO films were studied by different techniques.

Multilayer additive manufacturing of catalyst-coated membranes for polymer electrolyte membrane fuel cells by inkjet printing

Inkjet printing is a versatile, contactless and accurate material deposition technology. The present work is focused on developing innovative strategies for inkjet printing of Catalyst-Coated Membranes (CCM) by performing Additive Manufacturing (AM) applied to Polymer Electrolyte Membrane Fuel Cells (PEMFC), without resorting to intermediate substrates. Three different approaches for AM are presented and discussed: a) inkjet-printing of the membrane ionomer layer and the top catalyst layer; b) inkjet-printing of both catalyst layers onto a membrane; c) inkjet-printing of the ionomer layer as well as the catalyst layers onto the reinforcement layer of the membrane. The produced catalyst and membrane layers were characterized and proved uniform in terms of catalyst loading (0.2–0.4 and 0.08 mgPt cm−2 for cathode and anode, respectively), ionomer distribution and thickness homogeneity (4 μm for catalyst layers). The fully inkjet-printed CCM outperformed conventionally made assemblies in electrochemical-performance testing, even reaching 15% higher power density.

In-situ thickness control of centimetre-scale 2D-Like polydopamine films with large scalability

The possible 2D-like arrangement of monomers in polydopamine films obtained by autoxidation of the dopamine at the air/water interface was recently reported. Therefore, the morphological and chemical properties should be controllable by tuning the synthesis conditions. In this work, to optimise the synthesis conditions, films were obtained at the air/water interface with different dopamine concentrations, various pH and stirring speeds. The growth of the films was monitored in situ by spectroscopic reflectometry. The obtained films were transferred onto Si(100) substrates, and their morphological parameters were examined by Atomic force microscopy. X-ray diffractometry, Raman spectroscopy, and X-ray photoelectron spectroscopy allowed studying the chemistry of the films. The control of the growth process was achieved at the centimetre-scale level in terms of thickness homogeneity, chemical and structural characteristics of the obtained films. Transfer of the films onto substrates did not affect the homogeneity, foreshadowing an opportunity for large scalability of the process. Structural and chemical studies revealed successful synthesis of a clear 2D-like ordered structure without unreacted dopamine moieties. Finally, molecular dynamics simulations showed a good agreement with the literature information and revealed new insights on the self-assembly process at the air/water interface.

Examining the Role of Aryldiazonium Salts in Surface Electroinitiated Polymerization.

Historically, the irreversible reduction of aryldiazonium salts has provided a reliable method to modify surfaces, demonstrating a catalogue of suitable diazonium salts for targeted applications. This work expands the knowledge of diazonium salt chemistry to participate in surface electroinitiated emulsion polymerization (SEEP). The influence of concentration, electronic effects, and steric hindrance/regiochemistry of the diazonium salt initiator on the production of polymeric films is examined. The objective of this work is to determine if a polymer film can be tailored, controlling the thickness, density, and surface homogeneity using specific diazonium chemistry. The data presented herein demonstrate a significant difference in polymer films that can be achieved when selecting a variety of diazonium salts and vinylic monomers. A clear trend aligns with the electron-rich diazonium salt substitution providing the thickest films (up to 70.9 ± 17.8 nm) with increasing diazonium concentration and electron-withdrawing substitution achieving optimal homogeneity for the surface of the film at a 5 mM diazonium concentration.