Backbone-Constrained Tripeptides Enable Sequence Control of Solid-State Dynamics.

<p><b>The wettability of a surface is determined by two factors; the chemistry of the surface, which determines the inherent chemical hydrophilicity or hydrophobicity, and the physicality of the surface, whereby the surface roughness enhances and exaggerates the inherent hydrophilicity or hydrophobicity of the surface. Hence, controlling the wettability of a surface requires manipulation of both the chemical nature of the surface and the surface roughness. This research predominantly investigated controlling the wettability of surfaces through creation and manipulation of surface roughness, but also studied alterations of the chemical hydrophilicity and hydrophobicity of surfaces. These studies were performed using two different substrates, for different potential commercial applications. Wool fabrics were studied, in order to increase their hydrophobicity and produce a stain and water repellent wool fabric. 3D printed polymers were also investigated in order to create surfaces with useful wetting behaviours, including superhydrophobicity and anisotropic wetting.</b></p> <p>First, wool fabrics were manipulated through physical processing alone, in order to increase the surface roughness. This relied on altering the arrangement of the micrometre–sized wool fibres in the fabrics and creating a more disordered array. This was achieved through hand–felting of the wool fabrics and was found to successfully increase the surface roughness of the fabrics, and hence increase the hydrophobicity. However, it was found that the increased felting led to detectable increases in the macro–scale roughness of the surface, reducing the soft hand feel of the wool fabrics. This effect is an undesirable property in the textiles industry and another physical process of shearing protruding wool fibres was investigated in order to reduce this macro–scale roughness and increase the softness of the fabric. However, this processes was found to also reduce the micro-scale roughness of the surface and hence, the hydrophobicity of the fabrics was also decreased. This decrease in hydrophobicity was exacerbated due to the increased chemical hydrophilicity of the surface due to the exposure of more fibre ends, which are hydrophilic. Hence, the hydrophobicity of the sheared fabrics was reduced to a level lower than the untreated fabrics. Therefore, the use of physical processes to increase the roughness of wool fabrics was found to be successful in increasing the hydrophobicity of the surfaces. However, as the soft texture of the wool fabrics was compromised, the fields of application of these fabrics was determined to be somewhat limited.</p> <p>Subsequently, the hydrophobicity of wool fabrics was increased using chemical modifications to increase the surface roughness, while not compromising the soft texture of the fabrics themselves. In these investigations, the surface roughness was again increased, but on a smaller scale, through the functionalisation of wool fibres with inorganic particles on the micro- or nano-scale. Three types of particles were investigated, gold nanoparticles, Ag/AgCl particles and CaCO3 particles. The gold nanoparticle functionalisation successfully increased the surface roughness on a very small scale, but the concurrent increase in chemical hydrophilicity was found to outweigh this increased surface roughness and result in a net decrease in hydrophobicity of the functionalised fabrics. The Ag/AgCl and CaCO3 functionalisations both successfully increased the hydrophobicity of the wool fabrics. Of these treatments, the Ag/AgCl functionalisation was found to have the greatest impact on increasing the hydrophobicity and Ag/AgCl functionalised fabrics showed increased water repellency in practical tests. The Ag/AgCl functionalisation also renders the fabrics antimicrobial, due to the known antimicrobial activity of silver nanoparticles (present as silver nanodomains on AgCl microparticles in Ag/AgCl composites). Hence, these investigations led to the development of water and stain repellent, and antimicrobial wool fabrics with great potential for commercial applications.</p> <p>Polymer substrates and 3D printing were used in order to create surfaces with specific surface roughness patterns and changeable surface chemistry for the purpose of creating surfaces with controlled wetting behaviours. For these investigations, a fused deposition modelling (FDM) 3D printing process was used to facilitate rapid prototyping of surface roughness pattern designs and allow for optimisation of these designs. These surfaces were printed using acrylonitrile butadiene styrene (ABS). Firstly, a highly hydrophobic surface was designed. An array of droplet-shaped structures was printed onto a flat substrate. These droplet structures were on the size scale of a few hundred micrometres, but the process of melting and extruding the polymer in the printing process also gave the surface some degree of smaller scale roughness. This roughness was then increased further, by functionalising the surface with silver nanoparticles. This functionalisation was achieved in-situ and also rendered the surface antimicrobial. Due to the inherent chemical hydrophilicity of silver, the surfaces also required a subsequent treatment with a fluoroalkyl silane (FAS) to render them chemically hydrophobic. While these surfaces did not achieve the typically defined conditions of superhydrophobicity, they were found to be highly hydrophobic and were also antimicrobial. Hence, these surfaces were deemed to be potentially useful for commercial applications in healthcare industries.</p> <p>FDM 3D printing was also used to create a surface with anisotropic wetting behaviour. This was achieved through printing a surface with 1-dimensional roughness in the form of protruding lines extending in one direction across the surface plane. These surfaces were printed using ABS or polylactic acid (PLA). Different shapes, sizes and spacings of these lines were investigated and these parameters were optimised. The resulting surface displayed significant anisotropy in its wetting behaviour with highly hydrophobic behaviour observed in the direction parallel to the protruding lines, but significantly more hydrophilic behaviour in the perpendicular direction. Hence, this surface allowed the movement of water in one direction across the surface but hindered movement in the perpendicular direction. This surface was then treated with a FAS, and subsequently treated with ion implantation in selected areas, using varied fluence of Ar+ or C+ ions. The FAS treatment served to change the surface chemistry from that of the printed polymer to a generic hydrophobic chemistry, using a surface treatment that is applicable to many different substrate materials. The ion implantation treatment significantly decreased the hydrophobicity of the treated areas of the FAS functionalised surface; in fact the ion implantation treatment was found to render the selected areas formally hydrophilic. This allowed for the design of a surface with both hydrophilic and hydrophobic areas, that allowed for movement of water in only one direction across the surface. Such a surface has potential applications in water harvesting, utilising the hydrophilic areas for condensation of water from the air, and the hydrophobic areas for movement of this water across the surface toward a collection tank.</p> <p>The research carried out herein led to the successful increase in hydrophobicity of wool fabrics using both physical and chemical processes. 3D printing was also successfully utilised to create two different surfaces with controlled wetting behaviours. Firstly, a surface with high hydrophobicity and antimicrobial activity was produced. And secondly, a surface with anisotropic wetting behaviour and areas of hydrophilicity and areas of hydrophobicity was achieved. Possible applications of these surfaces were considered.</p>

The article presents results of research on the wetting ability of aqueous solutions of short-chain alcohols in relation to selected hydrophobic materials. Polyethylene and Teflon were used as standard hydrophobic smooth materials. Dried peat with granulation d < 0.5 mm was used as the porous hydrophobic material. Physical properties of alcohols and their solutions having a direct influence on the rate of saturation of capillary layers have been discussed. The wettability of smooth surfaces was characterized by the advancing and receding contact angles and wetting tension, defined as the product of the liquid surface tension and cosine of contact angle. The contact angles were determined by Wilhelmy’s method using the Krüss K-100 tensiometer. Wettability of peat was determined by measuring the mass rate of liquid imbibition by capillary forces. For comparison, analogous tests of wettability and capillary imbibition rates were carried out using sodium dodecyl sulfate solutions and solutions of typical wetting agent used in firefighting activities. The solutions of surfactants, in the range of concentrations used in extinguishing operations, showed much better wetting properties in relation to a smooth hydrophobic surface (polyethylene) than solutions of alcohols in the entire range of concentrations (up to 100%). The imbibition capacity of the hydrophobic peat layers of alcohol solutions with concentrations above 10% was higher than the solutions of surfactants.

The creation of new materials is absolutely essential for developing new technologies. However, experimental efforts toward the material discovery are usually based on trial-and-error approach and thus require a huge amount of time and money. Alternatively, computational predictions can now provide a more systematic, rapid, inexpensive, and reliable method for the design of novel materials with properties suitable for new technologies. This dissertation describes the technique of theoretical predictions and presents the results on the successfully predicted and already produced (in some cases) unusual molecules, clusters, nanoparticles, and solids. The major part of scientific efforts in this dissertation was devoted to rationalizing of size- and composition-dependent properties of the materials based on understanding of their electronic structure and chemical bonding. It was shown that understanding relations between bonding and geometric structure, bonding and stability, and bonding and reactivity is an important step toward rational design of new, yet unknown materials with unusual properties. Our findings led to the discovery of the first simplest inorganic double helix structures, which can be used in the design of novel molecular devices. A significant part of this work also deals with the pseudo John-Teller effect, which potentially can be a powerful tool for rationalizing and predicting molecular and solid state structures, their deformations, transformations, and properties. Therefore, the works on the pseudo Jahn-Teller effect presented in this dissertation can be considered the steps toward further generalization and elevation of the pseudo Jahn-Teller effect to a higher level of understanding of the origin of molecular and solid state properties.

Titanium alkoxides Ti(OR)4 (R = Et, Pri and Bun) react with tris(hydroxymethyl)nitromethane (THMNM-H3) with retention of their basic tetrameric structural unit even after hydrolysis and condensation. The chemical reactivity of these molecular precursors are analyzed using a model based on a point charge approximation of density functional equations. Based on these theoretical results plausible reaction pathways can be anticipated, providing a deep insight into the mechanism of formation of these new molecular structures. Consequences for the sol–gel processing of titania-based material and for the rational design of novel solid-state materials are also briefly addressed.

Wetting properties at the surface of iota-carrageenan-based edible films

Rational design of multifunctional membrane material with underwater superoleophobicity for dye contaminated emulsion separation

The effects of the continuity of the surface pattern on wetting enhancement was investigated using micropillar and microhole arrays on hydrophilic and hydrophobic materials. Isolated micropillar arrays and continuous microhole arrays were prepared by a microscale imprinting technique using positive and negative Si molds fabricated by a conventional photolithography technique. The contact angles (CAs) and contact angle hysteresis (CAH) of the prepared surfaces were measured as a function of the surface parameter ξ, defined as the ratio of the top surface area of the microstructure to the surface area of the flat unit cell. It was found that the CAs of the micropillar array monotonically increased as the surface ratio decreased, regardless of the native wettability of the solid. However, an abnormal and consistent decrease of the CAs for the microhole array was observed when ξ < 0.5. To investigate the mechanism of this abnormality in wetting enhancement, the energy barriers for normal direction wetting, the so-called wetting transition from Cassi-Baxter (CB) wetting to Wenzel wetting, and lateral direction wetting, that is, spreading, were investigated with consideration of the trapped air in the microhole. The analysis unveiled that the hydrophobicity of the hydrophilic surfaces are attributable to the liquid-air interface pinning at the discontinuous edge of the pillar, which results in CB wetting. The abnormal decrease in the CAs of the microhole-patterned surfaces with ξ < 0.5 has been attributed to the relatively low energy barrier for spreading influenced by the continuity of the three-phase contact line. Additionally, trapped air in the microhole also plays a role in the spreading of water droplets by hindering the wetting transition from CB wetting to Wenzel wetting.

Enhanced deep-red emission in donor-acceptor molecular architecture: The role of ancillary acceptor of cyanophenyl

Mechanically attached, solid-state films of [Os(bpy)2 bpt Cl] have been formed on platinum microelectrodes and their voltammetric properties investigated, bpy is 2,2′-bipyridyl and bpt is 3,5-bis(pyridin-4-yl)-1,2,4-triazole. Scanning electron microscopy reveals that voltammetric cycling in 1.0 M HClO4 converts the amorphous array of microscopically small particles into a plate-like semi-crystalline form. In contrast, crystallisation does not occur when the films are cycled in 1.0 M NaClO4. In both electrolytes, the voltammetric response of these films is reminiscent of that observed for an ideal reversible, solution phase redox couple. Slow and fast scan linear sweep voltammograms have been used to provide an absolute determination of the fixed site concentration and apparent diffusion coefficient, Dapp. The fixed site concentration is 1.65 ± 0.05 M for films cycled in either electrolyte and the Dapp values increase with increasing electrolyte concentration, Celec. These observations suggest that ion transport rather than the rate of electron self-exchange limit the overall rate of charge transport through these solids. In 1.0 M NaClO4, Dapp values for oxidation and reduction are identical at 8.3 ± 0.5 × 10−12 cm2 s−1. In 1.0 M HClO4, Dapp is significantly lower and depends on whether the deposit is being oxidised (9.7 ± 0.4 × 10−13 cm2 s−1) or reduced (6.3 ± 0.4 × 10−13 cm2 s−1). These data have been used to obtain an insight into the relative importance of intra- s. inter-particle charge transport. When Celec>0.5 M, the standard heterogeneous electron transfer rate constant, k°, becomes independent of the electrolyte concentration with a value of 1.7 ± 0.2 × 10−5 cm s−1 being observed in both 1.0 M NaClO4 and HClO4. Significantly, the distance normalised heterogeneous electron transfer rate constant for these solid state films is almost three orders of magnitude smaller than that found within a spontaneously adsorbed monolayer of the same complex. The importance of these results for the rational design of solid-state redox active materials for battery, display and sensor applications is considered.

Magnesium hydride (MgH2) is considered a promising solid-state hydrogen storage material due to its high hydrogen capacity, low cost, and excellent reversibility. However, its practical use is still limited by high dehydrogenation temperatures and slow kinetics. To overcome these challenges, we conducted ab initio molecular dynamics (AIMD) simulations based on density functional theory (DFT) to study the catalytic role of nickel (Ni) clusters (Ni1-Ni7) supported on the MgH2 surface. The formation energies and binding energies of different Ni cluster configurations were calculated to identify the most stable structures. Charge density difference and Bader charge analyses showed significant charge transfer among Mg, Ni, and H atoms, which promotes hydrogen activation. Radial distribution function analysis at 298 and 500 K revealed that small clusters, especially Ni3 and Ni4, achieve an optimal balance between hydrogen binding strength and structural flexibility. Moreover, mean square displacement results indicated that the Ni4 cluster markedly enhances hydrogen mobility at higher temperatures. To understand the catalytic mechanism, we analyzed the total and projected density of states (TDOS and PDOS), velocity autocorrelation function (VACF), and vibrational density of states (VDOS). The results confirm that subnanometer Ni clusters─particularly the Ni4-2 configuration─act as efficient catalysts for enhancing the dehydrogenation performance of MgH2, offering valuable insights for the rational design of advanced hydrogen storage materials.

Polymer-protein interactions are crucial for determining the activity of both polymer and protein for many bio-related applications. Poly(ethylene glycol) (PEG) as a well-known antifouling material is often coated on surfaces to form highly solvated brushes, which exhibit excellent protein-repellent properties. However, unlike surface-induced antifouling effects, little is known about the intrinsic PEG-protein interactions in aqueous solution, which is an important yet neglected problem. Here, we investigate the interactions between PEG and proteins in aqueous solution using fluorescence spectroscopy, atomic force microscopy (AFM), and nuclear magnetic resonance (NMR). Two important characteristics, molecular weight of PEG and mass ratio of PEG : protein, are examined to determine the effect of each on PEG-protein interactions as well as binding characteristics between PEG and proteins. In contrast to too long and too short PEG chains, collective results have shown that PEG with optimal molecular weight (MW) is more capable of interacting with proteins, which induces the conformational change of proteins through more stable binding sites and stronger interactions with long chain PEG. Enhanced PEG-protein interactions are likely due to the change of hydrophilicity to amphiphilicity of PEG with increasing MWPEG. In contrast to almost none or weak interactions of PEG surfaces with proteins, this work provides new evidence to demonstrate the existence of interactions between PEG and proteins in aqueous solution, which is important not only for better understanding of the structure-activity relationship of PEG both in solution and on surfaces, but also for the rational design of new PEG-based materials for specific applications.

Imagine if solid state materials could be designed over multiple length scales and created with precise control over their various forms of complexity. An integrated approach is being used to efficiently combines theory, synthesis, and operando characterization to control, assemble, and stabilize solid state materials and with various forms of complexity for enhancement of ion and/or electron transport. While computational materials design is a well-established with many known successes in the field of Li-ion chemistry, compounds are usually not designed with defects in mind or an understanding of what synthetic pathway can be utilized to achieve them. By understanding how materials complexity influences electrochemical performance, we are advancing comprehensive rational materials design beyond the level of defect-free design. Furthermore, the science of synthesis needs to consider extrinsically controlled complexity. A large-scale effort has been established which combines extensive and state of the art in situ and ex situ characterization tools. This talk will provide an overview of the results and approaches being taken as they relate to energy storage and conversion applications.

ConspectusLayered transition metal (TM) compounds arepivotal in the developmentof rechargeable battery technologies for efficient energy storage.The history of these materials dates back to the 1970s, when the conceptof intercalation chemistry was introduced into the battery. This processinvolves the insertion of alkali-metal ions between the layers ofa host material (e.g., TiS2) without causing significantstructural disruption. This breakthrough laid the foundation for Li-ionbatteries, with materials like LiCoO2 becoming key to theircommercial success, thanks to their high energy density and good stability.However, despite these advantages, challenges remain in the broaderapplication of these materials in batteries. Issues such as latticestrain, cation migration, and structural collapse result in rapidcapacity degradation and a reduction in battery lifespan. Moreover,the performance of batteries is often constrained by the propertiesof the available materials, particularly in layered oxide materials.This has driven the exploration of materials with diverse compositions.The relationship between composition and structural chemistry is crucialfor determining reversible capacity, redox activity, and phase transitions,yet predicting this remains a significant challenge, especially forcomplex compositions.In this Account, we outline our effortsto explore rational principlesfor optimal battery materials that offer a higher performance. Thecore of this is the concept of ionic potential, a parameter that measuresthe strength of the electrostatic interaction between ions. It isdefined as the ratio of an ion’s charge to its ionic radius,offering a quantitative way to evaluate interactions between cationsand anions in crystal structures. By building on this concept, weintroduce the cationic potential, which is emerging as a crystallographictool that captures critical interactions within layered oxide materials.This approach provides insights into structural organization, enablingthe prediction of P2- and O3-type stacking arrangements in layeredoxides. A key advantage of using the cationic potential is its abilityto guide the rational design of electrode materials with improvedperformance. For example, introducing P-type structural motifs intothe material framework can significantly enhance ion mobility, mitigatingdetrimental phase transitions that often compromise battery efficiencyand longevity. Furthermore, ionic potential serves as a representativeparameter to quantitatively describe the properties of various TMcompositions, providing a straightforward calculation method for designingmultielement systems. We anticipate that this Account will providefundamental insights and contribute to significant advancements inthe design of layered materials, not only for battery applicationsbut also for broader fields that require control of the material properties.

The depletion of fossil fuels has accelerated the search for clean, sustainable, scalable, and environmentally friendly alternative energy sources. Hydrogen is a potential energy carrier because of its advantageous properties, and the electrolysis of water is considered as an efficient method for its industrial production. However, the high-energy conversion efficiency of electrochemical water splitting requires cost-effective and highly active electrocatalysts. Therefore, researchers have aimed to develop high-performance electrode materials based on non-precious and abundant transition metals for conversion devices. Moreover, to further reduce the cost and complexity in real-world applications, bifunctional catalysts that can be simultaneously active on both the anodic (i.e., oxygen evolution reaction, OER) and cathodic (i.e., hydrogen evolution reaction, HER) sides are economically and technically desirable. This Minireview focuses on the recent progress in transition-metal-based materials as bifunctional electrocatalysts, including several promising strategies to promote electrocatalytic activities for overall water splitting in alkaline media, such as chemical doping, defect (vacancy) engineering, phase engineering, facet engineering, and structure engineering. Finally, the potential for further developments in rational electrode materials design is also discussed.

Organic room-temperature phosphorescence (RTP) materials with large Stokes shifts and prolonged afterglows are gaining increasing attention in a variety of applications, including displays, anti-counterfeiting, sensing, and bioimaging. However, achieving high-performance organic RTP remains challenging due to weak spin-orbit coupling, rapid non-radiative decay, and unstable triplet excitons. Early studies focused on crystal engineering, as ordered lattices restrict molecular motion and stabilize triplet excitons. Analyzing crystal structures and packing provides valuable insights into intermolecular interactions, while theoretical calculations have clarified electronic structures, laying the foundation for rational RTP material design. However, recent findings suggest RTP in many single-component systems may arise from trace impurities, significantly influencing RTP properties. This discovery has greatly advanced the understanding of impurity-induced phosphorescence. This review systematically examines the role of impurities in RTP, detailing their origins from starting materials, solvents, and side reactions. It also explores how these identified impurities can serve as essential building blocks for designing new RTP materials. Finally, essential methods for evaluating compound purity, emphasizing the critical importance of rigorous analysis and validation are presented. Material purity plays a pivotal role in RTP research, as impurities can distort experimental data, potentially leading to misinterpretations that can impede advancements in understanding the underlying mechanisms.