Organic-based Materials Research Articles

On-Surface Synthesis of 2D Polymers at the Liquid-Solid Interface

Unraveling the structure and dynamics of the formation of covalent and non-covalent organic-based 2D crystalline materials is key to controlling the quality of these materials, such as the defect density and their size. Understanding these characteristics is important for controlling their properties. This contribution highlights our efforts in using scanning probe microscopy, particularly scanning tunneling microscopy (STM), to visualize the structure and dynamics of substrate-supported metal-organic frameworks (sMOFs) and substrate-supported covalent organic frameworks (sCOFs) at the liquid-solid interface.We will focus on the growth of covalent organic frameworks, primarily based on boroxine chemistry, and reveal both qualitative and quantitative details of the nucleation-elongation processes in real-time and under ambient conditions. Sequential data analysis enables the observation of the amorphous-to-crystalline transition, the time-dependent evolution of nuclei, the existence of 'non-classical' crystallization pathways, and, importantly, the experimental determination of essential crystallization parameters with excellent accuracy, including critical nucleus size, nucleation rate, and growth rate. Other aspects that will be addressed include sCOFs and chirality, as well as the formation of multilayered sCOFs. Additionally, we demonstrate that in specific cases, the electric field between the STM tip and the substrate can induce, on demand, the polymerization or depolymerization process.

Plasma electrolytic oxidation based superhydrophobic coatings: fabrication, rudiments, and constraints

AbstractPlasma electrolytic oxidation (PEO) has evolved as a versatile technique for depositing low surface energy organic-based materials useful in fabricating superhydrophobic (SHP) coating materials. The application of silane-based polymeric organic materials atop PEO coating is the most common method to prepare coating materials for wetting and corrosion protection. Herein, the latest developments in PEO-based coatings employing polymeric/silane-based organic materials with the inclusion of ceramic oxides are reviewed, with emphasis on the structure, wettability, and corrosion resistance. The relevant and existing fundamental design theories and strategies for fabricating highly efficient SHP PEO coatings are also outlined and discussed. The systemic design of SHP coatings by deposition from organic particle dispersion and their inclusion into PEO-micropore layers, as well as the most important parameters affecting the properties of PEO-assisted SHP-based coatings, are highlighted. Furthermore, the merits and challenges of the PEO-assisted SHP-based coating fabrication are critically evaluated to identify remaining challenges and future research directions.

Tribological and mechanical exploration of polymer-based hemp and colemanite composite as a friction material

Natural and organic-based composite materials are widely used in many industrial applications due to their low cost, easy recyclability, economic feasibility, and ready availability. In this study, a polymer-based composite friction material consisting of Hemp-Colemanite composition (HCFCo) has been developed for the automotive sector to exhibit lower cost, environmentally friendly characteristics, and suitable friction-wear behaviors. For this purpose, three different ratios (%4, %8 and %12) of HCFCo composites were produced using a coating technique called impregnation process with a specially designed device. During the production stage, homogeneity of the composites was ensured, and then the final shape was given by the hot pressing method. Local based natural materilas frequently used for as anon-asbestos friction materails. For this reason, hemp and colomanited based composites were tested. Properties such as hardness, density, water and oil absorption, friction coefficient, and specific wear of HCFCo samples were examined. In addition, the microstructures of HCFCo composites were investigated to determine the bonding form between hemp fiber and colemanite. The results obtained revealed that the friction coefficient values decreased with an increase in temperature, while no significant change was observed in hardness and density values. Throughout the entire testing process, the friction coefficients varied between 0.14 and 0.29 on average. It was concluded that the developed fiber-reinforced composite can be reliably used in industrial applications and can contribute significantly to innovations in the literature.

Recent advances in biocatalytic C–N bond-forming reactions

Molecules containing C–N bonds are of paramount importance in a diverse array of organic-based materials, natural products, pharmaceutical compounds, and agricultural chemicals. Biocatalytic C–N bond-forming reactions represent powerful strategies for producing these valuable targets, and their significance in the field of synthetic chemistry has steadily increased over the past decade. In this review, we provide a concise overview of recent advancements in the development of C–N bond-forming enzymes, with a particular emphasis on the inherent chemistry involved in these enzymatic processes. Overall, these enzymatic systems have proven their potential in addressing long-standing challenges in traditional small-molecule catalysis.

Polyimide-Based Aqueous Potassium Energy Storage Systems Using Concentrated WiSE Electrolyte.

Aqueous batteries are considered as promising alternative power sources due to their eco-friendly, cost-effective, and nonflammable attributes. Employing organic-based electrode materials offers further advantages toward building greener and sustainable systems, owing to their tunability and environmental friendliness. In order to enhance the energy and power densities, superconcentrated aqueous electrolytes, such as water-in-salt electrolytes (WiSE), have renewed the interest in aqueous batteries due to their enhanced stability and much wider electrochemical stability window (>1.23 V) compared with the traditional aqueous electrolytes. Here, we present a perylene diimide-based electrode material (PDI-Urea) as an appealing anode for aqueous potassium energy storage systems and investigate their electrochemical performance in three WiSE electrolytes, namely, 30 M potassium acetate, 40 M potassium formate and 30 M potassium bis(fluorosulfonyl)imide (KFSI). To explore the potential of PDI-Urea for potassium-based electrochemical energy systems, we fabricated full cell devices such as aqueous potassium dual-ion battery (APDIB) and aqueous K-ion battery (AKIB) and studied their electrochemical properties with 30 M KFSI electrolyte. The full cell K-ion battery, using a PBA cathode, exhibited excellent electrochemical performance with good rate capability and impressive capacity retention of 91% upon 1000 cycles. Further, the reaction mechanism of the electrodes is systematically analyzed using ex-situ studies.

Gold(I) complexes as powerful photosensitizers - a visionary frontier perspective.

Singlet oxygen production and its reactivity have significant implications in fields ranging from polymer science to photodynamic therapy. Extensive research has focused on the development of organic-based materials and heavy metal complexes, including Ru(II), Rh(III), Ir(III) and Pt(II). However, metal complexes containing Au(I) have been scarcely explored and warrant further investigation. This review provides a comprehensive analysis of reported compounds, classified based on the ligands coordinated to the gold(I) centre. Additionally, future directions in photosensitizer development and singlet oxygen applications are discussed.

Donor-Acceptor Conjugated Acetylenic Polymers for High-Performance Bifunctional Photoelectrodes.

Due to the drastic required thermodynamical requirements, a photoelectrode material that can function as both a photocathode and a photoanode remains elusive. In this work, we demonstrate for the first time that, under simulated solar light and without co-catalysts, donor-acceptor conjugated acetylenic polymers (CAPs) exhibit both impressive oxygen evolution (OER) and hydrogen evolution (HER) photocurrents in alkaline and neutral medium, respectively. In particular, poly(2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine) (pTET) provides a benchmark OER photocurrent density of ~200 μA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE) at pH 13 and a remarkable HER photocurrent density of ~190 μA cm-2 at 0.3 V vs. RHE at pH 6.8. By combining theoretical investigations and electrochemical-operando Resonance Raman spectroscopy, we show that the OER proceeds with two different mechanisms, with the electron-depleted triple bonds acting as single-site OER in combination with the C4-C5 atoms of the phenyl rings as dual sites. The HER, instead, occurs via an electron transfer from the tri-acetylenic linkages to the triazine rings, which act as the HER active sites. This work represents a novel application of organic-based materials and contributes to the development of high-performance photoelectrochemical catalysts for the solar fuels' generation.

Heterostructured organic/MoS2 nanowall with synergistic SERS enhancement enabling direct and sensitive detection of contaminants

In recent years, the π-conjugated organic molecular system has attracted considerable attention for its surface-enhanced Raman scattering (SERS) properties. However, the practical application of π-conjugated organic materials as SERS substrates is limited due to the inefficient dissociation of excitons, weak enhancement, and poor reproducibility. Herein, we proposed a novel nanowall SERS heterocomposite based on 3D D(C7CO)-BTBT nanowalls and 2D few-layer MoS2 flakes. A significant SERS activity of the D(C7CO)-BTBT/MoS2 nanowall heterocomposite can be achieved by the charge transfer (CT) resonance enabled by the π-conjugated interactions between D(C7CO)-BTBT and MoS2 and the electromagnetic field spatial distribution induced by the D(C7CO)-BTBT nanowalls. The concentration limit of detection (LOD) of the methylene blue (MB) molecules absorbed on the heterostructured D(C7CO)-BTBT/MoS2 nanowall substrate is as low as 8.2 × 10−11 M, which is excellent among the reported organic-based substrates. A practical SERS detection for the 100 nm polystyrene (PS) nanoparticles on the D(C7CO)-BTBT/MoS2 substrates can be down to 4.5 × 105 ng/L, which is exceptional for the real-time monitoring of emerging contaminants based on SERS technology. This research not only provides a new SERS enhancement strategy for organic-based materials, but also may be helpful in exploring a potential candidate for SERS detection of emerging contaminants.

Thermal control of a small satellite in low earth orbit using phase change materials-based thermal energy storage panel

Thermal control of small satellites in low earth orbit (LEO) is not easy due to the intermittent heating conditions. The satellites in LEO are sometimes present in the illumination zone and other times in the eclipse zone, which imposes difficulties keeping their temperatures within the safe range. The present study investigates a thermal energy storage panel (TESP) integrated with phase change materials (PCM) to control the temperatures of satellite subsystems. The TESP was made of aluminium with outer dimensions of 100 mm long, 71 mm wide, and 25 mm high. The PCMs used were organic-based materials, which were RT 12, RT 22, and RT 31. The TESP was tested under two thermal powers of 11 W and 14 W. These powers are typical of satellite subsystems. The finite volume method was adopted for thermal analysis of the TESP. The significance of this study is that it provides a detailed computational analysis of the TESP for microsatellites' temperature management under typical LEO conditions. The research outcomes show a significant advancement in the thermal managing performance of PCM-based TESP. RT 22 could reduce the highest temperature by 4.7 % and raise the lowest by 9.5 %. It was observed from the analysis that the PCM with intermediary melting temperature provided better thermal control efficiency. RT 12 reported a lower extreme temperature difference (ETD) and could decrease it by 63.9 % relative to the case with no PCM. At the same time, RT 22 reported an ETD of 23 min and could reduce it by 63 % relative to the case with no PCM at 14 W. The present study concluded that PCMs show great potential as a viable approach for effectively thermally managing devices that experience cyclic thermal fluctuations, such as the subsystems of satellites operating in LEO.

Promoting X-ray scattering data analysis with two-dimensional correlation spectroscopy

In situ X-ray scattering (XrS) experiments provide an impressive level of detail about microstructures and their evolution following a change in environment in soft matter; however, a major obstacle is examining the huge amount of data. In this work, the applications of two-dimensional correlation spectroscopy (2DCS) in the XrS data analysis are demonstrated with three exemplary studies. The responses of three typical soft-matter systems (thin film, solution and solid) to a change in environment (i.e. concentration, temperature) were chosen as the subjects of this study. In situ grazing-incidence small-angle X-ray scattering, small-angle X-ray scattering and wide-angle X-ray scattering results were analyzed with the 2DCS method. On the basis of Noda's rule, it is demonstrated that the 2DCS-XrS results could not only disclose the weak scattering signal common to organic-based materials but also determine the sequential order of the structures of interest by referring to their strong response to a change in environment. It is expected that the 2DCS method could promote XrS data analysis in a simple, fast and reliable way, which might interest users without extensive X-ray scattering knowledge. These features could help to convert XrS data into knowledge that can be implemented in advanced materials preparation.

Fungal Biodeterioration and Preservation of Miniature Artworks.

The study of biodeterioration is an important issue to allow the best conservation and prevent the decay of cultural heritage and artworks. In Naples (Italy), a particular museum (Museodivino) preserves the miniature artworks representing Dante's Divine Comedy and Nativity scenes, executed with organic-based materials in walnut and clay shells. Since they showed putative signs of biodeterioration, the first aim of this study was to verify the presence of microbial colonization. A culture-dependent approach and molecular biology allowed us to isolate and identify the sole fungal strain Aspergillus NCCD (Nativity and Dante's Divine Comedy) belonging to the A. sydowii sub-clade. Based on this result, a sustainable and eco-friendly approach was applied to find a method to preserve the miniature artwork by contrasting the growth of the strain NCCD. Several essential oils used as a natural biocide were tested against Aspergillus strain NCCD belonging to the A. sydowii subclade to determine their potential antimicrobial activity. Results revealed that basil, cloves, fennel, and thyme essential oils exerted antifungal activity, although their effect depended also on the concentration used. Moreover, anoxic treatment and the control of the relative humidity were used in the presence of thyme, in vitro, and in vivo assays to define the impact on fungal growth. No fungal development was detected in vivo in the shells treated with thyme essential oil at high relative humidity after 60 days of incubation at 28 °C. These results highlighted that although relative humidity was the major factor affecting the development of the strain Aspergillus NDDC, the application of thyme in an anaerobic environment is essential in contrasting the fungal growth. Identifying the biodeterioration agent allowed us to plan an eco-friendly, non-destructive approach to be successfully used to guarantee the conditions suitable for conserving miniature artwork.

Designing Nanostructured Organic-Based Material by Combining Plasma Polymerization and the Wrinkling Approach.

In this work, an innovative and versatile strategy for the fabrication of nanostructured organic thin films is established based on the wrinkling phenomenon taking place in a bilayer system constituted by a liquid plasma polymer film (PPF) and a top Al coating. By means of morphological characterization (i.e., atomic force microscopy and scanning electron microscopy), it has been demonstrated that the wrinkle dimensions (i.e., wavelength and amplitude) evolve as a function of the PPF thickness according to models established for conventional polymers. The wrinkled surfaces exhibit great stability over time as their dimension did not vary after 100 days of aging, resulting from a pinning phenomenon between the Al layer and the Si substrate, hence freezing the morphology. In a second step, the wrinkled surfaces have been employed as templates for the deposition of an additional PPF third layer, giving rise to the formation of a nanostructured organic-based surface. The chemical composition of the material can be tuned through an appropriate choice of precursor (i.e., allyl alcohol or propanethiol).

Fabrication of organic based thermal resistance material using pyrolyzed cellulose nanofiber and carbon fiber for high performance thermal insulation

Herein, polymer-based thermal insulating composites are fabricated using pyrolyzed cellulose nanofiber (p-CNF) and carbon fiber (CF) in order to overcome the existing limitations of organic-based thermal resistance materials. The p-CNF is prepared by iodine treatment and calcination. The pyrolyzed CNF/CF composites are then fabricated via the freeze casting of two-dimensional (2D) CFs to obtain a low thermal conductivity of 0.058 W/mK, along with a high thermal stability, high tensile stress. Therefore, the p-CNF/CF composite provides an efficient thermal insulation performance via low thermal conductivity along with a high thermal degradation temperature, thereby demonstrating the potential for the development of thermal resistance materials.

Investigating the stretchability of doped poly(3-hexylthiophene)-block-poly(butyl acrylate) conjugated block copolymer thermoelectric thin films

Organic-based thermoelectric materials have become increasingly popular for their ability to convert waste heat into electricity, coupled with their low processing costs, mechanical flexibility, and non-toxicity, making them an attractive option for wearable electronics. However, there is a lack of direct integration of intrinsically stretchable semiconducting polymers in wearable thermoelectric devices. This study investigates the potential of using poly(3-hexylthiophene)-block-poly(butyl acrylate) (P3HT-b-PBA) copolymers doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) to develop stretchable thermoelectric devices. Two PBA block lengths, with number molecular weights (Mn) of 3,000 and 6,000, were compared to pristine P3HT homopolymer. We found that all films exhibited edge-on orientations before and after doping, as determined by GIWAXS analysis. The lamellar distance increases while the π − π stacking distance decreases upon doping, indicating that the dopants preferentially allocate in the side-chain domain. Accordingly, the optimized power factor (PF) of the doped P3HT-b-PBA3k and P3HT-b-PBA6k films are found to be 2.13 and 1.42 μW m−1 K−2, respectively; and the stretchable thermoelectric device comprising P3HT-b-PBA3k and a poly(dimethylsiloxane) (PDMS) substrate demonstrate good stretchability with a high PF of 1.77 μW m−1 K−2 at 50% strain, and a high PF retention 86.3% relative PF after 200 stretch/release cycles. This outstanding performance highlights the feasibility of fabricating stretchable thermoelectric device by using intrinsically stretchable semiconducting polymer. The study presents a promising approach for creating stretchable thermoelectric devices using conjugated/insulating block copolymers combining the thermoelectric properties of P3HT and the intrinsic softness of PBA.

An evolutionary-driven AI model discovering redox-stable organic electrode materials for alkali-ion batteries

Data-driven approaches have been revolutionizing materials science and materials discovery in the past years. Especially when coupled with other computational physics methods, they can be applied in complex high-throughput schemes to discover novel materials, e.g. for batteries. In this direction, the present work provides a robust AI-driven framework, to accelerate the discovery of novel organic-based materials for Li-, Na- and K-ion batteries. This platform is able to predict the open-circuit voltage of the respective battery and provide an initial assessment of the materials redox stability. The model was employed to screen 45 million small molecules in the search for novel high-potential cathodes, resulting in a proposed shortlist of 3202, 689 and 702 novel compounds for Li-, Na- and K-ion batteries, respectively, considering only the redox stable candidates.

Effects of fermented and supplemented chicken manure on the nutrient management aspects of an apple orchard

AIt is a huge challenge for farmers worldwide to successfully increase the organic matter content of their soils and improve their water balance at the same time. Therefore, the main aim of the study is to develop and test organic-based nutrient composite materials that can be successfully used by farmers to increase soil organic matter content, improve water management parameters and implement water-efficient technologies. The study was performed in the orchard of the Institute of Horticultural Science of the University of Debrecen in Hungary (Debrecen-Pallag). The experiment was set up in a ten-year-old apple (Malus domestica ‘Pinova’) orchard. In the trial, fermented poultry manure and superabsorbent polymers (SAP) were used at different doses to study their effects on soil properties and fruit quality. Applied composite materials increased the nitrate and organic nitrogen content of the soil. Treatments did not affect the sugar content of the fruits but significantly and positively affected the individual fruit weight and the titratable acidity of the fruits.

Conducting Polymer Switches Permit the Development of a Frequency-Reconfigurable Antenna

Conjugated polymers (CPs) undergo a wide range of reversible intrinsic property changes including electrical conductivity, electromagnetic absorption, volume, and charge mobility upon electrochemical oxidation/reduction, which has made them popular as ON/OFF organic-based switchable materials. Recent studies on the insulating-to-conductive transition within CPs have paved the way for a next generation of flexible switches that permit the creation of “dynamic” electric circuits. Here, we present an approach to a low-voltage, low-power electrochemically controllable, switchable, and printable CP-based conductive element that acts as a platform for the configuration of frequency-reconfigurable radiative antennas. We demonstrate that the DC conductivity of a soluble PEDOT derivative, PE2, film can be switched electrochemically by 4 orders of magnitude across large insulating gaps up to 15 mm within 20 s. Its integration in a DC switching element that is incorporated along the poles of a half-wave dipole antenna structure is able to generate an AC resonant frequency switch, and thus a radiation frequency shift, in the microwave (i.e., 1–2 GHz) range. This type of printable antenna fills an important need for the demand of bandwidth that is growing beyond the crowded frequency spectrum, by relying on the development of frequency-reconfigurable antenna systems capable of dynamically tuning their spectral properties when desired.

Organic Thermoelectric Nanocomposites Assembled via Spraying Layer-by-Layer Method

Thermoelectric (TE) materials have been considered as a promising energy harvesting technology for sustainably providing power to electronic devices. In particular, organic-based TE materials that consist of conducting polymers and carbon nanofillers make a large variety of applications. In this work, we develop organic TE nanocomposites via successive spraying of intrinsically conductive polymers such as polyaniline (PANi) and poly(3,4-ethylenedioxy- thiophene):poly(styrenesulfonate) (PEDOT:PSS) and carbon nanofillers, and single-walled carbon nanotubes (SWNT). It is found that the growth rate of the layer-by-layer (LbL) thin films, which comprise a PANi/SWNT-PEDOT:PSS repeating sequence, made by the spraying method is greater than that of the same ones assembled by traditional dip coating. The surface structure of multilayer thin films constructed by the spraying approach show excellent coverage of highly networked individual and bundled SWNT, which is similarly to what is observed when carbon nanotubes-based LbL assemblies are formed by classic dipping. The multilayer thin films via the spray-assisted LbL process exhibit significantly improved TE performances. A 20-bilayer PANi/SWNT-PEDOT:PSS thin film (~90 nm thick) yields an electrical conductivity of 14.3 S/cm and Seebeck coefficient of 76 μV/K. These two values translate to a power factor of 8.2 μW/m·K2, which is 9 times as large as the same films fabricated by a classic immersion process. We believe that this LbL spraying method will open up many opportunities in developing multifunctional thin films for large-scaled industrial use due to rapid processing and the ease with which it is applied.

Hartree method for molecular polaritons

The formation of the composite photonic-excitonic particle, known as a polariton, is a phenomenon emerging in materials possessing strong coupling to light. The organic-based materials besides the strong light-matter coupling also demonstrate strong interaction of electronic and vibrational degrees of freedom. We study the vibration-assisted polariton wave-function evolution treating both types of interactions as equally strong. Using the multiconfiguration Hartree approach we derive the equations of motion for the polariton wave function, where the vibration degrees of freedom interact with the polariton quantum field through the mean-field Hartree term. For the conventional quadratic polariton Hamiltonian and the Holstein-type vibration Hamiltonian (Tavis-Cummings-Holstein model), the obtained equations are in one-to-one correspondence with the original Schr\"odinger equation. In the second part of the paper, we show that our theory reproduces the physical properties of the polariton light emission spectrum. In particular, the theory explains experimental observations of the molecular Stokes shift in the polariton fluorescence spectra in the systems with strong light-matter coupling. We also investigate the behavior of the polariton wave function in the vicinity of the anticrossing point and demonstrate that the Hartree term can produce an infinite potential barrier of a dynamical origin, which is responsible for the formation of the mixed upper-lower polariton states. The nonlinear nature of the polariton theory reflects their collective behavior. We expect that the multiconfiguration Hartree approach being applied to polaritons and similar systems will result in a manifestation of new physical phenomena.

Engineering promising A-π-D type molecules for efficient organic-based material solar cells

ABSTRACT Within this work, to promote the efficiency of organic-based solar cells, a series of novel A-π-D type small molecules were scrutinised. The acceptors which we designed had a moiety of N, N-dimethylaniline as the donor and catechol moiety as the acceptor linked through various conjugated π-linkers. We performed DFT (B3LYP) as well as TD-DFT (CAM-B3LYP) computations using 6-31G (d,p) for scrutinising the impact of various π-linkers upon optoelectronic characteristics, stability, and rate of charge transport. In comparison with the reference molecule, various π-linkers led to a smaller HOMO–LUMO energy gap. Compared to the reference molecule, there was a considerable red shift in the molecules under study (A1–A4). Therefore, based on the analysis of energy level, A4 and A3 were shown to be promising non-fullerene acceptors with the designed donors for applications in solar cells. It is hoped that the current study would provide theoretical insights into the design and amplification of optoelectronic characteristics of suggested frameworks on a grand scale in comparison with the reference molecules.