Formulation Composition Research Articles

Graphene-Based Composites for Biomedical Applications: Surface Modification for Enhanced Antimicrobial Activity and Biocompatibility.

The application of graphene-based materials in medicine has led to significant technological breakthroughs. The remarkable properties of these carbon materials and their potential for functionalization with various molecules and compounds make them highly attractive for numerous medical applications. To enhance their functionality and applicability, extensive research has been conducted on surface modification of graphene (GN) and its derivatives, including modifications with antimicrobials, metals, polymers, and natural compounds. This review aims to discuss recent and relevant studies related to advancements in the formulation of graphene composites, addressing their antimicrobial and/or antibiofilm properties and evaluating their biocompatibility, with a primary focus on their biomedical applications. It was concluded that GN surface modification, particularly with compounds intrinsically active against bacteria (e.g., antimicrobial peptides, silver and copper nanomaterials, and chitosan), has resulted in biomaterials with improved antimicrobial performance. Furthermore, the association of GN materials with non-natural polymers provides composites with increased biocompatibility when interfaced with human tissues, although with slightly lower antimicrobial efficacy. However, it is crucial to highlight that while modified GN materials hold huge potential, their widespread use in the medical field is still undergoing research and development. Comprehensive studies on safety, long-term effects, and stability are essential before their adoption in real-world medical scenarios.

Optimizing Polymer-Stabilized Raw Earth Composites with Plant Fibers Reinforcement for Historic Building Rehabilitation

This research focuses on the optimization of formulation, characterization, and damage analysis of plant fiber-reinforced polyester resin composites (jute and date palm). To better understand the characteristics and mechanical behavior of these materials, this study investigates the influence of resin content and plant fibers on the physico-mechanical behavior of the resin composites. Resinous composites consisting of polyester resin and raw earth were studied using a novel formulation based on an empirical method that follows the principle of earth saturation with polyester resin. Saturation was achieved with a 28% content of polyester resin, which appeared to be an optimal blend for the earth–resin composite. Plant fibers were randomly incorporated as reinforcement in the composites at various percentages (1%, 2%, and 3%) and lengths (0.5 cm, 1 cm, and 1.5 cm). Mechanical tests including bending, compression, and indentation were conducted to evaluate the mechanical properties of the composites. Analysis of fracture morphology revealed that the deformation and rupture mechanisms in bending, compression, and indentation of these composites differ from those of traditional concrete and cement mortar. The obtained results indicate that the composites exhibit acceptable performance and could be favorably employed in the rehabilitation of historic buildings.

Effect of guar gum-chitosan composites edible coating functionalized with essential oils on the postharvest shelf life of Khasi mandarin at ambient condition

In the present study, the effects of guar gum (0.7 %):chitosan (0.3 %) based composite edible coating functionalized with coconut oil and essential oils like clove bud oil and cinnamon bark oil were investigated on the postharvest shelf life of Khasi mandarins at ambient conditions (25 ± 5 °C, RH 75 ± 5 %) up to 20 days of storage period. The postharvest characteristics such as weight loss, firmness, acidity, total soluble solids (TSS) and reducing sugar of control and treated fruits were evaluated at 5 days intervals throughout the storage period. The obtained results indicated that the application of guar gum/chitosan-based composite edible coating with coconut oil, clove bud and cinnamon bark essential oil was effective in prolonging the postharvest shelf life of Khasi mandarins as compared to control fruits by minimizing the decay and loss of postharvest quality attributes. The treatment of composite such as guar gum/chitosan/coconut oil/clove oil/cinnamon oil (GGCsC-Cl-Cn) was most effective in maintaining postharvest characteristics of fruits compared to other treatments and control. The significant (p < 0.05) lowest weight loss (38 %) with retention of higher firmness (5.9 N), titratable acidity (0.29 %), and total soluble solid (10.8 %) was noticed in the Khasi mandarins treated with GGCsC-Cl-Cn composite coating on 20 days of storage. Furthermore, the present study confirmed the significance of the developed composite formulation in improving the shelf life of Khasi mandarin.

A novel mixing rule model to predict the flowability of directly compressed pharmaceutical blends

In the pharmaceutical industry, powder flowability is an essential manufacturability attribute to consider when selecting the suitable manufacturing route and formulation. The selection of the formulation is usually based on the physical and chemical properties of the Active Pharmaceutical Ingredient (API) under consideration. Current industrial practice heavily relies on experimental work, which often results in significant labor and API consumption that results in higher costs. In this study we describe the development of a mixing rule to predict powder blend flowability from the flow properties of the individual components for industrial formulations manufactured via Direct Compression (DC). The mixing rule assumes that the granular solids’ interactions are dominated by cohesive forces but are pragmatic to calibrate from the perspective of the typical data collated in an industrial environment. The proposed model was validated using a range of different APIs and the results show that the model can effectively predict the flowability properties of any formulation across the space of DC-relevant formulation compositions. Finally, a connection between the model and APIs properties (shape and size) was investigated via a linear correlation between the API particle properties and interparticle forces.

State and prospects of fish processing technologies

The fishing industry plays a significant role in ensuring food security and nutrition of the world's population. Therefore, analysing the trends in the flourishing of aquaculture and natural fisheries, the specifics of the use of raw materials for food, the degree of provision of the population with these products and new processing technologies is an urgent task to determine the priority areas for improving the nutritional and biological value of aquaculture products, taking into account modern nutrition recommendations. The purpose of the study was to investigate the current state of the fish industry, innovative areas of aquatic products manufacturing to identify promising areas of fish and seafood technology. The study was conducted using a comparative analysis of scientific works by domestic and foreign scientists published in the Scopus, Web of Science, Journal Citation Reports, Scimago Journal &amp; Country Rank, and Google Scholar databases. The analysis of the information shows an increase in the catch of aquatic organisms in the world, and in recent years, the total catch has amounted to more than 177.80 million tonnes. For food purposes, 157.40 million tonnes were used, with an annual consumption of 20.2 kg per person. The mass share of Ukraine in the total volume of fish products in the world is 0.2%. Ukraine is importdependent in terms of aquatic organisms. The latest technologies for processing fish products are related to the development of methods for assessing the quality of raw materials and products, the creation of low-waste technologies for the extraction of biologically active compounds and the formation of multicomponent food products based on plant and animal raw materials, and the use of biotechnological and physical methods to improve product quality. The involvement of a new raw material object, the freshwater toothless mollusk, for food purposes has been noted, and many culinary recipes from this species with additives of plant materials have been developed. However, there is a lack of research in the area of improving the technologies and formulation composition of fish pastes, which will make it possible to formulate food products with specified properties of biological value to meet human needs. The practical significance of the analysis is to identify promising trends in aquaculture technologies, taking into account Ukraine's own raw material base

Effects of Modifying Agent and Conductive Hybrid Filler on Butyl Rubber Properties: Mechanical, Thermo-Mechanical, Dynamical and Re-Crosslinking Properties.

Ionic crosslinking of bromobutyl rubber (BIIR) composites was prepared using butylimidazole (IM) and ionic liquid (IL), combined with carbon nanotubes (CNT) and conductive carbon black (CCB) to enhance the intrinsic properties and heal ability of the resulting composites. Variation in the BIIR/CNT-CCB/IM/IL ratios was investigated to determine the appropriate formulation for healing the composites. Results showed that the mechanical properties were increased until the IM:IL:CNT/CCB ratio reached 1:1:1/1.5, corresponding to the optimal concentration of 5:5:5/7.5 phr. Thermo-oxidative degradation, as indicated using temperature scanning stress relaxation (TSSR), demonstrated the decomposition of the composites at higher temperatures, highlighting the superior resistance provided by the proper formulation of BIIR composites. Additionally, the conditions for the healing procedure were examined by applying pressure, temperature, and time. It was observed that the composites exhibited good elasticity at 0 °C and 60 °C, with a high rate of re-crosslinking achieved under appropriate pressure and temperature conditions. This research aims to develop a formulation suitable for the tire tread and inner liner of commercial car tires together with artificial skin products.

Determining key features of the operation of percussion downhole drilling machines

Dnipro University of Technology is a leading institution where an authoritative scientific school was formed to solve the fundamental issues of percussive-rotary drilling with the help of hydraulic hammers. This method makes it possible to intensify significantly the mining processes of rock mass breaking. In order to perform the specified function as fully as possible, hydraulic hammers are to work in a certain technological mode and have appropriate technical characteristics; the paper deals immediately with the analysis of those characteristics. The original designs of hydraulic hammers proposed by the authors are distinguished by a high degree of reliability of the interaction of individual parts and assemblies. Simulation of the operation of hydraulic hammers under appropriate mode-parametric support revealed a number of their significant advantages, i.e. in terms of creating effective conditions for rock mass disintegration. It has been proven convincingly that some features of the approaches to the implementation of a hydraulic well washing programme correspond to the stability of a high-quality process of the downhole work of percussion machines. As a result of the research, a composition of some rational formulations of flushing fluids, which contribute to a significant acceleration of the development of destructive processes, was clarified.

Biodegradable Water-Soluble Matrix for Immobilization of Biocidal 4-Hexylresorcinol.

Biocidal coatings have been used in biomedicine, cosmetology and the food industry. In this article, the coatings are described as being composed of non-stoichiometric polycomplexes, products of electrostatic coupling of two commercial biodegradable ionic polymers, anionic sodium alginate and cationic quaternized hydroxyethyl cellulose ethoxylate. Non-stoichiometric polycomplexes with a 5-fold excess of the cationic polymer were used for immobilizing hydrophobic biocidal 4-hexylresorcinol (HR). Being dispersed in water, the polycomplex particles were capable of absorbing a tenfold excess of HR in relation to the polycation. After deposition onto the plastic surface and drying, the aqueous polycomplex-HR composite formulation forms a transparent homogeneous coating, which swells slightly in water. The interpolyelectrolyte complex (IPEC) is substantially non-toxic. The incorporation of HR in the IPEC imparts antimicrobial activity to the resulting composite, in both aqueous solutions and coatings, against Gram-negative and Gram-positive bacteria and yeast. The polysaccharide-based polycomplexes with embedded HR are promising for the fabrication of biocidal films and coatings.

Functional properties of selected composite gluten-free pseudocereals flour

Technological challenges in the development of gluten-free pseudocereal-based foods depend on grain physical characteristics and nutrient-dense flour functional properties. Gluten-free composite pseudocereal flour blends were prepared by blending amaranth flour, buckwheat flour, and quinoa flour in three distinct blending ratios: T1, T2, and T3, and their functional properties were compared to 100% wheat flour. In comparison to buckwheat and quinoa, amaranth grains are significantly (p < 0.05) smaller in length (1.30 ± 0.10) and width (0.99 ± 0.02) than other grains. Buckwheat (4.30 ± 0.05) has a length that is 58% shorter than wheat (7.29 ± 0.23). The functional properties of gluten-free composite flours, such as water absorption capacity, oil absorption capacity, swelling power, foaming capacity, bulk Density, water holding capacity, and water solubility index, have significantly (p < 0.05) differed from those of wheat flour. The water holding capacity, water solubility index, bulk density, swelling power, and oil absorption were decreased with an increase in the buckwheat and a decrease in the quinoa level in the formulation. However, the WAC of composite flour samples increased with the level of buckwheat flour and decreased with the level of quinoa flour in the composite flour formulations. The standardized gluten-free pseudocereal flour blends enhance functional food products' nutritional, textural, and sensory attributes.

A quality by design framework for developing nanocrystal bioenabling formulations

The present study aims to outline a rational framework for the design and development of a 1.0% (w/v) hydrocortisone nanocrystal-based formulation, resorting to a simple, efficient, and scalable nanonization methodology, based on the high-pressure homogenization (HPH) technique. Accordingly, the innovative product was comprehensively optimized following a Quality by Design (QbD) approach. The thorough selection of formulation composition was driven by a dual purpose: improving skin permeation and stability. In the early stage of development, a Failure Mode, Effects and Criticality Analysis (FMECA) diagram was employed to identify the most impactful variables for the critical quality attributes (CQAs). In this sense, a rotatable, three-factor and five-level circumscribed central composite design (CCCD) was applied to investigate how squalene concentration (x1), soluplus concentration (x2) and HPH-time (x3) influence physicochemical properties, performance and physical stability of the formulation. A robust Design Space (DS) was defined, establishing the optimal settings for the critical variables, whose combination meets the requirements set in the quality target product profile (QTPP). Morphological analysis revealed the cuboidal shape of hydrocortisone nanocrystals. In what concerns colloidal properties, the most promising formulation disclosed a small particle size (Dx(50) = 311.8 ± 1.5 nm), along with narrow size distribution (span value = 1.91 ± 0.17). Zeta potential results (−2.19 ± 0.15 mV–−12.1 ± 0.4 mV) suggested a steric hindrance stabilization. FTIR spectra showed no chemical interactions between drug and formulation components. XRD diffractograms confirmed loss of crystallinity during the downsizing process. In vitro studies revealed an improvement on drug release rate (316 ± 21–516 ± 35 μg/cm2/√t), compared to the coarse suspension and commercial products, and a straight dependence on the stabilizer concentration and HPH time. The permeation flux across the skin (0.16 ± 0.02–1.2 ± 0.5 μg/cm2/h) appeared to be dependent on the drug physicochemical properties, in particular saturation solubility. Further characterization of the experimental formulations pointed out the role of the stabilizing component to prevent against physical instability phenomena. This organic solvent-free, and therefore “green” nanocrystal production technology offers great potential for pharmaceutical R&D and drug delivery by enabling the development of new forms of conventional drugs with optimal physicochemical properties and performance.

Machine learning enabled customization of performance-oriented hydrogen storage materials for fuel cell systems

Hydrogen storage materials with different crystal configurations have been extensively investigated for hydrogen promotion. To escape the dilemma of traditional trial-and-error composition optimization, in this work, efficient implicit/explicit features-based machine learning (ML) was applied for the first time to typical metal hydrides with the newly-constructed proprietary dataset. Excitingly, the most pivotal capacity-affecting factors (MeanIonicChar value/Fe content) were identified through feature importance ranking, facilitating efficient capacity estimation and formulation of high-capacity compositions. Subsequently, ML-based proactive properties scanning and composition customization were performed for fuel cell hydrogen feeding system. Generally, the measured hydrogen storage properties exhibit satisfactory accuracy and a validation relationship with the ML-based predicted values. In addition, an intrinsic link between atomic occupancy randomness and pressure-composition-temperature slope was revealed by theoretical calculations. Among the alloys developed from the advanced paradigms, Ti0.9Zr0.12Mn1.2Cr0.55(VFe)0.25 offers all-round properties (1.90 wt% / 127.30 kg H2/m3 in saturation) and overwhelming cost-effectiveness compared with the reported alloys at the moderate temperature and pressure level. In summary, ML-based composition customization pathways avoid substantial experimental investments and provide a novel option for efficient acquisition of high-performance hydrogen storage materials.

Energetic hydrogen-bonded open-framework as promising green combustion catalyst for nitramine-based solid propellants

The development of halogen-free nitramine-based green solid propellants has attracted a significant interest due to their application in rapidly developing aerospace technologies. However, relatively low burn rates, and generation of high pressure in the combustion chamber limit applications of such propellants. The alleviation of these problems could be achieved by using suitable combustion catalysts. Herein, a new energetic nitrogen-rich open framework compound 1 was prepared and evaluated as an efficient Pb-free combustion catalyst for HMX-nitrocellulose-nitroglycerin solid composite propellant formulation. Compound 1 was synthesized by a straightforward one-step process, its structure was comprehensively characterized by x-ray crystallography, and it was found to be thermostable (decomposition at 289 °C), insensitive to mechanical impact and friction (60 J, 360 N), and showed high hydrolytic stability. A propellant formulation containing 3.0 wt.% of 1 exhibited 45% increase in its burning rate (under 6.0 MPa) versus catalyst-free reference propellant. In the pressure range of 3–10 MPa, the pressure exponent was calculated to be 0.32, which is more than two times lower than of the reference propellant. These impressive properties of catalyst 1 suggest that it has a great potential to be further used in the development of future highly energetic green solid propellants.

Effect of hybridization on mechanical and water absorption properties of short palmyra palm leaf stalk/carbon fibers reinforced polyester composites

AbstractRecently, there has been interest in the development of hybrid composites for diverse industrial applications. In this aspect, this paper explores the mechanical (tensile, flexural, impact, and dynamic mechanical analysis) and water (distilled and seawater) absorption properties of palmyra palm leaf stalk/carbon fiber‐based composites. Hybrid composites with various reinforcement weight ratios were manufactured for the experiment employing the compression molding procedure. To analyze the hybridization effect, composites with a single reinforcement were also produced and evaluated. The results demonstrated that adding carbon fiber to palmyra fiber in the matrix enhances the composites' overall mechanical properties. Field emission scanning electron microscope (FESEM) was used to assess the broken surface of mechanically tested composites to better comprehend the failure causes. The findings of the moisture absorption test have shown that using carbon fiber in composites reduces moisture absorption due to their hydrophobic behavior. In addition, the specimens dipped in seawater absorbed more water due to the higher pH value of seawater and gained more weight due to salt deposition. The results of this study indicate that the hybrid composite formulation P25C75 exhibits a balance between its mechanical properties and environmental resilience, making it a possible lightweight material for structural applications.Highlights Various properties of palmyra palm/carbon hybrid composites were investigated. Addition of carbon fibers to palmyra palm composites enhanced their properties. Hybrid composites exhibit better‐damping property. Performance, environmental effect, and cost are balanced in hybrid composites.

Fabrication and In vitro Evaluation of Carbopol/Polyvinyl Alcohol-based pH-sensitive Hydrogels for Controlled Drug Delivery.

Diclofenac sodium has a short half-life (about 1.5 hours), requiring repeated administration, and as a result, serious complications, such as GI bleeding, peptic ulcer, and kidney and liver dysfunction, are generated. Hence, a sustained/controlled drug delivery system is needed to overcome the complications caused by the administration of diclofenac sodium. This study aimed to fabricate and evaluate carbopol/polyvinyl alcohol-based pH-sensitive hydrogels for controlled drug delivery. pH-sensitive carbopol/polyvinyl alcohol graft-poly(acrylic acid) hydrogels (Cp/PVA-g-PAa hydrogels) were developed for the controlled delivery of diclofenac sodium. The combination of carbopol/polyvinyl alcohol, acrylic acid, and ethylene glycol dimethacrylate was used as polymer, monomer, and cross-linker, respectively. The effects of the formulation's composition on porosity, swelling index, and release pattern of diclofenac sodium from the developed hydrogels were investigated. An increase in porosity and swelling was observed with the increasing amounts of carbopol and acrylic acid, whereas polyvinyl alcohol showed the opposite effect. Due to the formation of a highly viscous system, the drug release decreased with the increasing concentrations of carbopol and polyvinyl alcohol while increased with increasing acrylic acid concentration. The pH-responsive properties of the fabricated hydrogels were demonstrated by dynamic swelling and drug release studies at three different pH values. Higher dynamic swelling and diclofenac sodium (model drug) release were found at high pH values compared to low pH values, i.e., pH 7.4 > 4.6 > 1.2, respectively. Cytotoxicity studies reported no toxic effect of the prepared hydrogels, thus indicating that the prepared hydrogels are safe to be used on clinical basis. The prepared carbopol/polyvinyl alcohol crosslinked hydrogel can be used as a promising carrier for the controlled release of drugs.

Physical, reconstitution and phenolic properties of instant drink mix prepared with Moringa oleifera leaf, raw banana and whey protein concentrate

The formulation of instant drink mix with nutritional enhancement and optimum physical properties is a challenging task. The present study was undertaken to formulate instant drink formulation (IDF) mix using the ingredients green unripe mature banana powder (GMBP), Moringa oleifera leaf powder (MLP) and whey protein concentrate powder (WPCP) as main ingredients. Different combinations of these ingredients were mixed to formulate nine different variants (treatments) of composition mixes. The developed treatments were evaluated for physical and reconstitution properties of color characteristics, water activity, bulk density, tapped density, flowability, angle of repose, foaming capacity, swelling index, hygroscopicity, water absorption capacity (WAC), water solubility index (WSI), dispersibility, and wettability. The samples were evaluated for phenolic composition and antioxidant potential. Water activity, bulk and tapped density among the samples was ranging between 0.245–0.254 aw, 0.35–0.43 g/cm3 and 0.67–0.77 g/cm3, respectively. The flowability characteristics of Carr index (CI), Hausner ratio (HR) and angle of repose were ranging between 26.20–55.51, 1.36–2.34 and 27.51–48.33, respectively, with T1 treatment having the highest values for these characteristics. Foaming capacity, swelling index and hygroscopicity was found to be 21.83–51.17 %, 3.55–10.16 % and 24.53–36.67 %, respectively. The WAC and WSI was observed to be highest in the T1 treatment with 2.55 and 76.27, respectively. Whereas, the dispersibility and wettability was found to be between 49.75–87.93 (%) and 14.15–22.46 (s), respectively. Total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC) in the analyzed samples were ranging between 26.86 and 1740.00 mg GAE/100 g, 12.33–1880.50 mg RE/100 g and 0.27–448.83 μg C3G/g, respectively. For the antioxidant assays, the DPPH, ABTS and FRAP assay were recorded with 10.30–8.36 % inhibition, 11.85–88.07 % inhibition and 0.36–22.72 μM Fe2+/100g, respectively. Polyphenol profile and enzyme inhibition activity was analyzed among the formulated compositions.

Fabrication and investigation of paraffin based shape-stable composite phase change materials with styrene ethylene butylene styrene as supporting skeleton for low temperature thermal energy storage and management

Paraffin based composite phase change materials (PCMs) have gained intensive attentions in low temperature thermal energy storage (TES) and management application domains because of its suitable melting temperature range and advanced thermoproperties. Seeking decent structural supporting materials (SSM) and the associated manufacturing approaches that capable of fabricating paraffin composites at appropriate temperatures to avert the thermal decomposition of the paraffin particularly for low-molecule ones are in high demand. Herein, we developed a low-molecule paraffin (RT18HC) composite through a simple blending approach by using styrene-ethylene/butylene-styrene (SEBS) as SSM, and showed that such SEBS-paraffin composites could be able to fabricate at a low operation temperature of 80 °C, significantly lower than that required for the preparation of conventional high density polyethylene (HDPE)-paraffin composites. To enhance the composite effective thermal conductivity, a micro-sized graphite power as enhancer was also involved over the fabrication process. Owing to the desirable solubility of paraffin in SEBS, a crosslinking structure inlaying paraffin and graphite was formed, endowing the composite with ability to maintain the structure stabilization and eliminate the graphite sedimentation over the repeated thermal cycles. 10 wt% of SEBS gives the composite optimum formulation at which 10 wt% graphite can be involved, and also an excellent shape stability and thermal adjustment ability can be achieved.

Emulsions containing composite (clove, oregano, and cinnamon) essential oils: Phase inversion preparation, physicochemical properties and antibacterial mechanism.

Natural essential oils (EOs), especially those combining different individual EOs (also termed composite EOs) with enhanced performance, are becoming healthy, market-sought food preservatives/additives. This study aims to provide insights into the challenge regarding EOs processing due to their low solubility and the elusive mechanism under the enhanced bio-reactivity of composite EOs. A unique oil/water interacting network was created by phase-inversion processing, which enhances EO solubilization and emulsification to form composite EO formulations (EOFs) containing ordinary cinnamon, oregano and clove EOs. These EOFs mainly contained cinnamaldehyde, carvacrol and eugenol and exhibited excellent post-storage stability. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability of EOFs (at 15.880μL/mL) was>88%, and the Ferric reducing antioxidant power (FRAP) was 1.8mM FeSO4·7H2O. The minimum inhibitory concentration (MIC) of EOFs against E. coli and S. aureus was ∼7.940μL/mL. The EOFs could cause quick deterioration of bacterial structures, demonstrating high efficacy in bacteria-killing and anti-biofilm formation.

Experimental and theoretical study of PEG bulk volume fraction effect on clay/PEG2000 hybrid properties

This article focuses on the preparation of hybrids based on a clay matrix intercalated with poly(ethylene glycol) (PEG) molecules. Hybrids obtained by direct mixing in the presence of a solvent, in this case water, are intended mainly for the thermal insulation of buildings. The study highlighted the impact of the PEG bulk volume fraction, (φ), on the structure and properties of composite formulations for a molecular weight M=2000g/mol. Scanning electron microscopy (SEM) results showed that the structure of purified clay is heterogeneous, characterized by the existence of smectite, illite, kaolinite. These clay minerals are associated with spherical particles of average size ranging from 10 to 30μm, which are affected to quartz. Meanwhile, Fourier transform infrared spectroscopy (FTIR) was used to estimate the changes caused by the addition of PEG to the matrix. The results reveal a decrease in the intensities of the vibrational bands assigned to water molecules ν(HOH) at 3440cm-1 and δ(HOH) at 1638cm-1 as φ increases. This decrease is linked to the desorption of water molecules outside the interlayer environment thanks to the adsorption of PEG. On the other hand, the changes detected in the ν(O-H) band recorded at 3621cm-1 confirm the formation of a hydrogen bond between the PEG backbone and the siloxane surface. As for the X-ray diffraction (XRD) results, it is clear that adsorption takes place in two cycles characterizing the adsorption of two polymer layers. Each cycle contains three regimes including the dilute regime, the bidimensional semi-dilute regime and the plateau. Finally, XRD results were used to monitor the variation of d-spacing versus PEG bulk volume fraction. These results show very good agreement with the theory developed using De Gennes scaling laws for the different regimes near the surface.

Multi-criteria optimization of geopolymer foam composition

This study presents an approach to synthesizing a mathematical model for determining the composition of geopolymer foams. The focus is on improving the accuracy of multicriteria optimization for metakaolin-based geopolymer composite composition. Experimental data on the physical and mechanical properties of geopolymers are digitized to establish the computational basis for these calculations. Optimization criteria include density, porosity, compressive strength, flexural strength, Young's modulus, volumetric heat capacity, thermal diffusivity, and thermal conductivity. In addition, parameters such as shrinkage, processability, adsorption, adhesion, and economic aspects are also considered. The proposed format aims to fine-tune the geopolymer composite formulation by using the developed model for multi-criteria analysis of technological and physical-mechanical properties of foamed geopolymer composite materials (FGCM). A synthesis of mathematical models including the main criterion, suboptimization, generalized criterion, lexicographic optimization, sorting of alternatives, interval values, and decision tree methods was used to develop methods for multi-criteria optimization of the composition of foamed geopolymers. The study additionally uses the method of criteria convolution, in which the indices of specific criteria are modified in the form of a ratio scale to clarify the limits and boundaries of changes in the composition of the geopolymer mixture. This minimizes contradictory conclusions and expert opinions and highlights the extreme values for each group of parameters. By filtering the raw information, the accuracy of estimates is improved. The exclusivity of the proposed model for determining the composition of foamed geopolymers lies in the possibility of selecting the necessary formulation by mathematical processing of digitized information of the results of measurements of physical-mechanical and operational-technological properties according to the proposed innovative algorithms and schemes. Compared to existing methods, the focus of the proposed method allows for solving problems that are inaccessible to direct observation. This is due to the discovery of hidden information about the interaction of structural and strength parameters. Combining subjective and objective elements of the choice of the optimal geopolymer formulation, the proposed methodology of information processing allows for improving the quality of determining the optimal composition of the geopolymer mixture. The results of multicriteria optimization for foamed geopolymer indicate that the optimal component composition of the geopolymer matrix, within the selected range of variation, consists of 100g metakaolin, 90g potassium activator, 5g silica fume, 100g silica sand, 7g basalt fiber, and 3g aluminum. These proportions yield the best mechanical, thermal, and technological properties.

Control of Nanoparticle Dispersion, SEI Composition, and Electrode Morphology Enable Long Cycle Life in High Silicon Content, Nanoparticle-Based Composite Anodes for Lithium-Ion Batteries

Striking a balance between high theoretical capacity, Earth abundance, and compatibility with existing manufacturing infrastructure, silicon is one of the few materials that meets the requirements for a next-generation anode for rechargeable lithium-ion batteries. Due to complications with extreme volume changes during charging/discharging and reactive interfacial chemistries, however, the cycle-life of silicon-based composite anodes is unacceptable for broad use. Developing a majority silicon composite anode formulation that overcomes these challenges and is compatible with current industry manufacturing practices requires materials and chemical engineering solutions that account for both electrode morphology and interfacial chemistry. Here, we synthesize surface-functionalized silicon nanocrystals that enable a highly dispersed and homogeneous slurry that can easily be integrated into standard electrode fabrication process. We use this formulation to print a 76 wt. % silicon composite electrode. We show that the contents and the morphology of the silicon electrolyte interphase – a determining factor in the cycle life of silicon-based anodes – can be controlled with a post-synthetic thermal curing procedure. When paired against a capacity-matched lithium nickel manganese cobalt oxide LiNi0.8Mn0.1Co0.1O2 cathode, the cell retains 72% of its capacity through 1000 charge/discharge cycles while delivering an initial anode specific capacity of nearly 1000 mAh/g and an areal capacity of 2.55 mAh/cm2. Figure 1