Vapor Permeability Research Articles

The potential emulsions of xanthan gum and Daucus carota macerated oil in functional textiles for skincare applications: Formulation, characterization, and performance evaluation

This study investigates the formulation and characterization of functional textiles with skin hydration properties by using Daucus carota macerated oil-based O/W emulsions. The key novelty lies in obtaining skin-hydrating textiles by using Daucus carota macerated oil as an active compound. Ten O/W emulsions were prepared by mixing in different ratios of Daucus carota macerated oil, xanthan gum, Tween 80, and water. The droplet morphology (size and shape) and the properties of the emulsion (pH, conductivity, turbidity, surface tension, contact angle) were investigated as a function of each constituent variation in the formulation, maintaining the others constant, to find the proper conditions to obtain stable and compatible with skin application o/w emulsions. Selected emulsions were tested for their biocompatibility and antimicrobial properties. The biocompatibility test shows that the high surfactant content is cytotoxic to NHDF cells, whereas emulsions with less surfactant content are biocompatible, irrespective of the Daucus carota macerated oil content. The emulsion skincare effects were evidenced by skin hydration and antimicrobial analyses. The obtained results suggest that these bioactive emulsions have sufficient potential to be used in skincare finishes to textiles by applying them on a cellulosic fabric obtaining new functional textiles with skin hydration properties and good comfort indexes (hygroscopicity, air, and vapor permeability). This study opens new perspectives in the field of skincare textiles by exploring the moisturizing potential of Daucus carota macerated oil emulsions in obtaining functional supports with skin hydration properties. The results provide evidence that the obtained functional textiles show better skin hydration compared to the case with direct application of the emulsion on the skin. Thus, the textile support plays a significant role in creating an occlusive barrier that helps retain moisture and prevents the loss of water from the skin's surface. Consequently, skincare textiles could represent an excellent choice for skin hydration.

Evaluating Gelatin-Based Films with Graphene Nanoparticles for Wound Healing Applications

In this study, gelatin-based films containing graphene nanoparticles were obtained. Nanoparticles were taken from four chosen commercial graphene nanoplatelets with different surface areas, such as 150 m2/g, 300 m2/g, 500 m2/g, and 750 m2/g, obtained in different conditions. Their morphology was observed using SEM with STEM mode; porosity, Raman spectra and elemental analysis were checked; and biological properties, such as hemolysis and cytotoxicity, were evaluated. Then, the selected biocompatible nanoparticles were used as the gelatin film modification with 10% concentration. As a result of solvent evaporation, homogeneous thin films were obtained. The surface’s properties, mechanical strength, antioxidant activity, and water vapor permeation rate were examined to select the appropriate film for biomedical applications. We found that the addition of graphene nanoplatelets had a significant effect on the properties of materials, improving surface roughness, surface free energy, antioxidant activity, tensile strength, and Young’s modulus. For the most favorable candidate for wound dressing applications, we chose a gelatin film containing nanoparticles with a surface area of 500 m2/g.

Liquid Metal–Elastomer Seals for Stretchable Organic Electrolyte‐Based Lithium‐Ion Batteries

AbstractRapid progresses concerning wearable electronics call for stretchable batteries. Owing to the merits of high energy density and wide operating voltage range, organic electrolyte‐based lithium‐ion batteries (LIBs) take a large proportion in the powering markets. Due to the high sensitivity to moisture and oxygen, it is difficult to obtain long‐term reliable stretchable organic electrolyte‐based LIBs when they are directly exposed to the air. Benefiting from the outstanding gas impermeability of liquid metal (LM) and relatively good barrier properties for reactive acid gas molecules by polyisobutylene (PIB), an LM‐PIB seal is demonstrated for organic electrolyte‐based LIBs. In the seal, LM can prevent the inward permeation of oxygen and water vapor, and PIB can block the outward permeation of hydrolysis acid generated from the side reactions during the operation of the organic electrolyte‐based LIBs, which helps prevent the detrimental interaction between the hydrolysis acid and LM. A specific capacity of over 120 mAh g−1 is achieved and the battery shows consistent electrochemical performances under multiple deformations. This study offers a different design approach for long‐term operation of stretchable organic electrolyte‐based LIBs.

Zinc oxide nanoparticle-reinforced pectin/starch functionalized films: A sustainable solution for biodegradable packaging

Environmental pollution caused by non-biodegradable plastic pollutants adversely affects various ecosystems. This study proposes the development of novel functional and biodegradable films based on corn starch (CST) and pectin (PEC) containing zinc oxide nanoparticles (ZnONPs) from the casting method. The films exhibited processability, transparency, low water vapor permeation, and desirable mechanical properties for food packaging and coating applications. The ZnONPs acted as a plasticizer, enhancing the film elongation at the break, increasing the pec25-1 (PEC 25 wt% and ZnONPs 1 wt%) elongation from 79.85 to 162.32 %. The improved film elasticity supported by ZnONPs reduced the material stiffness. However, the films still demonstrated an average tensile strength (0.69 MPa) 17-fold higher than the tensile strength (0.04 MPa) of the non-biodegradable commercial film based on poly(vinyl chloride). Furthermore, the ZnONPs enhanced the UV-blocking capabilities of the films, leading to wettable materials with water contact angles lower than 90°. The films showed high biodegradation rates under natural disposal conditions. The results indicated that the pec25-1/ZnONPs film is a promising eco-friendly coating in food preservation due to its biodegradability, suitable mechanical properties, low water vapor permeability, and UV-blocking properties.

Enhancing fresh pear preservation with UV-blocking film coatings based on κ-carrageenan, cassava starch, and copper oxide particles

Renewable material packs have been an alternative to traditional petroleum-based products. Thus, this work aimed to develop an active and biodegradable coating based on κ-carrageenan/starch containing copper oxide particles (CuOPs) for fresh pears. The composite material was extensively characterized. Digital images of the coatings suggested stable and highly transparent materials. The composites presented handleability and flexibility. However, only the κ75 films prepared at 75:25 κ-carrageenan/starch weight ratio containing 0, 1, 1.5, and 2% (wt/wt) of CuOPs concerning the polysaccharide content demonstrated applicability as surface coatings for fresh pears. The water vapor permeation, tensile strength, and elongation at the break ranged from 1.14 × 10−10 to 1.59 × 10−10 Pa⋅m2·s−1, 26.19–101.67 MPa, and 6.73 to 17.05 wt%, respectively. Micrographs showed composite films with slight roughness and homogenous surfaces exhibiting hydrophilic characteristics supported by water contact angle measurements (between 71 and 84°). The films were durable for approximately 90 min in an aqueous solution, with the ability to expand their mass up to 3847% (sample κ75-0). The materials were tested as coatings on fresh pears under consumption conditions. The film κ75-2 conserved the fruit for consumption over 30 days, supporting better results than the commercial poly (vinyl chloride) pack. The composite material based on κ-carrageenan/starch containing CuOPs, especially the κ75-2 composite at 2.0% (wt/wt) of CuOPs, can be applied as a surface coating for fresh pears.

Effect of polymer structure on the functional properties of alginate for film or coating applications

This study aimed to characterize the effect of molecular weight (MW) and mannuronic/guluronic acids ratio (M/G) on the functional properties of four different alginate types, considering both the aqueous film-forming solutions (rheological and interfacial properties) and the self-standing films (mechanical and barrier properties). Regarding the film-forming solutions, a structure-dependent effect was clearly disclosed with respect to the flow properties. The high MW alginates showed greater values of apparent viscosity and a more pronounced shear-thinning behavior than low MW alginates. Surprisingly, the corresponding alginate films did not exhibit any significant difference in terms of Young modulus (≈1.9 GPa), elongation at break (≈8.4 %) and tensile strength (≈42.5 MPa), as well as oxygen and water vapor permeances (PO2 ≈ 7.0 ∙ 10−15 mol. m−2.s−1.Pa−1, and PH2O ≈ 1.0 ∙ 10−7 mol. m−2.s−1.Pa−1 at semi-dry condition and 25 °C). In addition, the best oxygen barrier performance was obtained for a film thickness of ∼20 μm, above which no significant increase in the oxygen barrier performance was noticeable. The outcome of this study suggests the potential of sodium alginate for specific food packaging applications, such as the manufacturing of edible films or functional coatings for packaging materials (e.g., plastics, paper, etc.), thus possibly meeting the increasing demand for more sustainable products and processes.

Preparation of porous membrane for moisture absorption from high‐humidity gases

AbstractSuitable air humidity is of great importance for human health, crop growth and the life of buildings. In this work, the polyvinylidene fluoride/calcium chloride (PVDF/CaCl2) porous membranes with rich pore structures for adsorption of high‐humidity gases were prepared using solvent evaporation‐induced phase separation. The results showed that the gap between the PVDF spherical crystals increased with the increase of CaCl2 content, which increased the porosity of the membrane. When the CaCl2 content reached 20 wt.%, the water vapor adsorption capacity of the PVDF/CaCl2 porous membrane was 0.876 and the initial adsorption rate was 0.050 g·g−1·min−1. At this point, the moisture vapor permeance of the membrane was the best at 0.04 g·m−2·h−1·Pa−1, and the dry strength of the PVDF/CaCl2 membrane was 0.397 MPa, which was 1.64 times that of the membrane without CaCl2. This work provides theoretical and technical guidance for the preparation of air dehumidification materials.Highlights The porosity of the membranes increased with increasing of calcium chloride content. The moisture vapor permeance of the M‐20 membrane was the best at 0.04 g·m−2·h−1·Pa−1. The dry strength of the M‐20 membrane was 1.64 times that of the M‐0 membrane.

A highly water-selective carboxymethylated cellulose nanofiber (CNF-CMC) membrane for the separation of binary (water/N2) and ternary (water/alcohols/N2) systems in vapor-permeation

A separation top layer was successfully deposited using cellulose nanofiber (CNF) and carboxymethylated cellulose nanofiber (CNF-CMC) on a cellulose acetate (CA) microfiltration membrane via the casting method since the filtration method resulted in the penetration of the coating solution into the membrane support. The CNF-CMC-based separation top layer displayed a uniform non-porous structure with a thickness of approximately 1.3 μm thus indicating that most of the membrane pore substrate was covered by CNF-CMC. In contrast, the CNF-based membrane exhibited a non-uniform porous structure within the range of 10–50 nm formed by aggregated CNFs, which is unsuitable for water vapor separation. The CNF-CMC membrane fabricated by the casting method exhibited a high water vapor permeation and H2O/N2 separation factor of 1.6 × 10−6 mol/(m2 s Pa) and 490, respectively, owing to the high dispersibility of the CNF-CMC solutions along with a reduction of macrovoids and microvoids. In ternary separation systems consisting of H2O/alcohols/N2 mixtures, the rich phase of carboxylate groups on the CNF-CMC enhanced the preferential sorption behavior of water vapor while preventing the permeation of isopropyl alcohol (IPA) and N2. The highest separation performance was observed in an H2O/IPA/N2 mixture with a high water vapor permeance level of 1.5 × 10−6 mol/(m2 s Pa) and an H2O/IPA permeance ratio exceeding 79,000.

Antibacterial durability of L-methionine modified cotton fabrics functionalized with ZnO nanoparticles

Cotton fabric based textiles utilizing metal oxide nanoparticles (NPs), offer potential options for reducing spreading of infection by bacteria due to their excellent antimicrobial properties, which depend on the nanoparticle's structure and morphology, as well as the fiber functionalization process. In this work, a simple padding and rolling technique for preparing antibacterial cotton fabrics by functionalizing their surface with nanostructured ZnO is demonstrated. L-methionine amino acid is utilized as a binding reagent due to its low toxicity to mammalian cells, biocompatibility with living tissues, and the presence of amine and carboxylic groups, which enhance its coordination capacity to improve ZnO adhesion. Zn(NO3)2·3H2O was precipitated as Zn(OH)2(s) using an alkali mixture of (NaOH+NaBH4), which was then converted into ZnO NPs up on heat treatment on the surface of modified cotton (LCt). Fourier transform infrared spectroscopy (ATR-FTIR) was utilized to confirm the chemical alteration of the fabrics by L-methionine. X-ray diffraction (XRD) investigations confirmed the crystalline structure, purity, and average crystallite size of the ZnO NPs (15.72 nm). X-ray photoelectron spectroscopy (XPS) tests revealed that the NPs were successfully coordinately bonded to the textiles. HR-SEM and energy-dispersive X-ray (EDS) mapping demonstrated that NPs were well-covered on the fabric fibers. The thermal degradation behavior of the modified and functionalized cotton was examined by thermal gravimetric analysis (TGA). The functionalized fabric shown outstanding antibacterial activity against gram-negative bacteria, E. coli and P. aeruginosa, as well as gram-positive bacteria S. aurous and S. pyogenes, with washing durability of up 50 wash cycles. After 50 wash cycles, approximately 88 % of the Zn was retained. This indicated a strong bond between the fabrics. Furthermore, the change has little effect on cotton qualities such as vapor permeability, water absorption, and water transport.

Fabrication of antimicrobial and high-toughness poly (lactic acid) composite films using tung oil derivatives

Tung oil derivatives are promising alternatives to traditional toxic plasticizers for improving the toughness of poly (lactic acid) (PLA) films. In this study, a tung oil-based quaternary ammonium salt (Q-ETO) was synthesized using a multi-step process involving epoxidation, ring opening, and substitution reactions. PLA based composite films with various amounts of Q-ETO were prepared by solvent casting. The impact of various amount of Q-ETO on PLA/Q-ETO composite films were evaluated with regard to their mechanical properties, hydrophilicity, water vapor permeability, optical properties, thermal stability, antibacterial properties, and leaching properties. The PLA/5%Q-ETO composite film yielded the highest elongation at break (82.52 ± 9.53 %), which was 153.67 % higher than that of pure PLA. All PLA composite films showed an antibacterial efficiency exceeding 90 % against both S. aureus and E. coli. Moreover, the PLA/Q-ETO composite film blocked the transmission of both ultraviolet and visible light while preventing the permeation of water vapor. The addition of Q-ETO only weakly affected the color and thermal stability of the PLA/Q-ETO composite film. Given the numerous advantages of the PLA composite film, it has significant potential for application as a food packaging material.

Investigation of film materials obtained from modified polyvinyl al-cohol-based solution systems

Films based on PVA solutions are currently attracting increasing attention due to their high transparency, barrier properties and environmentally friendly nature. This is due to the fact that PVA films have greater flexibility, transparency, impact strength and lower cost than other packaging materials. When discarded, PVA can decompose in the natural environment without adding to the pollution. The article is devoted to the study of film materials obtained from modified solution systems based on polyvinyl alcohol (PVA). Polyvinyl alcohol grade 098–10 was used as the starting product; glycerin grade T 94 was used as a plasticizer. The films were cast on glass, then heated in a heating cabinet at a temperature of 90 °C for 31 hours. The influence of different concentrations of PVA solutions on the barrier (vapor permeability) and physical and mechanical properties of films was studied. It was shown that, with an increase in the concentration of glycerol in PVA, the fracture resistance increased, the relative elongation noticeably decreased, and the permeability of the polymer sharply increased. The introduction of 20–30% plasticizer into PVA resulted in the production of a sufficiently elastic film, an increase in elongation at break, and also a decrease in tensile strength. The complex of studies carried out made it possible to determine the influence of modifying additives on the structural transformations of PVA compositions for the creation of new generation coatings. In the future, it is planned to continue research on this topic, in particular on optimizing the temperature-time regime of coating formation

The effects of formation and functionalization of graphene-based membranes on their gas and water vapor permeation properties

The gas and water vapor permeabilities of graphene-based membranes can be affected by the presence of different functional groups directly bound to the graphene network. In this work, one type of carboxylated graphene oxide (GO-COOH) and two types of graphene oxide synthesized i) under strong oxidative conditions directly from graphite (GO-1) and ii) under mild oxidative conditions from exfoliated graphene (GO-2) were used as precursors of self-standing membranes prepared with thicknesses in the range of 12–55 μm via slow-vacuum filtration preparation method. It was observed that the permeabilities for all tested gases decreased in order GO-2 > GO-1 > GO-COOH and depended on both the arrangement of graphene sheets and their functionalization. The GO-1 membrane with a high content of oxygen-containing groups showed the best performance for water vapor permeability. The GO-2 membrane with a thickness of 43 μm exhibited a disordered GO sheet morphology and, therefore, unique gas-separation performance towards H2/CO2 gas pair, showing high hydrogen permeability while keeping extremely high H2/CO2 ideal selectivity that exceeds the Robeson 2008 upper bound of polymer membranes.

Unleashing the potential of scalable, high-water vapor permeance graphene oxide membranes using electrospun supports

Dehumidification and dehydration technologies are projected to consume a substantial portion of the world's energy demand through the HVAC, and chemical processing industries. The development of highly permeable water-selective membranes represents a potential path to revolutionize these industries by drastically reducing their energy requirements. Selective layers based on graphene oxide (GO) have demonstrated the highest water vapor permeances to date, making GO a promising candidate for reducing the footprint and costs associated with commercial module development. However, most studies primarily focus on small-area membranes fabricated utilizing vacuum or pressure filtration, leading to either thick free-standing films or thin layers supported on model substrates such as anodic aluminium oxide. In this work, a casting approach is deployed to coat thin GO layers onto large-area membrane supports. In addition to the application of scalable methods, commonly used supports act as a significant bottleneck to the overall permeance. By designing highly porous (up to 92%) electrospun polystyrene supports, we demonstrate a 27% increase in overall permeance as compared to commercial Nylon and polyethersulfone supports even though these membranes have thicker GO selective layers. Despite the pore size in the electrospun material being larger than the GO flakes, the GO forms a selective layer via casting, and achieved water to nitrogen selectivity larger than 103.

Antiseptic Chitosan-Poly(hexamethylene) Biguanide Hydrogel for the Treatment of Infectious Wounds.

Topical wound infections create the ideal conditions for microbial colonization and growth in terms of moisture, temperature, and nutrients. When they are not protected, numerous types of bacteria from the internal microbiota and the external environment may colonize them, creating a polymicrobial population. Treatment of these wounds often necessitates the use of antibiotics that may have systemic harmful effects. Unlike antibiotics, topical antiseptics exhibit a wider range of activity and reduced systemic toxicity and resistance. In order to address this issue, we developed an antiseptic Chitosan-Poly (hexamethylene) Biguanide (CS-PHMB) hydrogel. The prepared hydrogel was characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). SEM images showed the smooth morphology and characteristic FTIR peaks of PHMB and confirmed the incorporation of the antiseptic into the chitosan (CS) hydrogel. A Water Vapor Permeation Rate study confirms the moisture retention ability of the CS-PHMB hydrogel. Rheological studies proved the gel strength and temperature stability. The prepared hydrogel inhibited the growth of S. aureus, P. aeruginosa, E. coli, methicillin-resistant Staphylococcus aureus (MRSA), and K. pneumoniae, which confirms its antibacterial properties. It also inhibited biofilm formation for S. aureus and E. coli. CS-PHMB hydrogel is also found to be hemo- and cytocompatible in nature. Thus, the developed CS-PHMB hydrogel is a very potent candidate to be used for treating infectious topical wounds with low systemic toxicity.

Effects of ultrasonic and ozone modification on the morphology, mechanical, thermal and barrier properties of corn starch films

Biodegradable starch material is considered one of the best alternatives to traditional petroleum-based synthetic plastics. The effects of ultrasound (40 kHz) and ozone (20 g/h) modifications on corn starch were investigated using ultraviolet absorption, titration, Fourier transform, differential scanning calorimetry, and X-ray diffraction. As well as the effects of the dual modification on biodegradable films' morphology, thickness, water content, water solubility, moisture absorption, water vapor permeation, opacity, water contact angle, and mechanical and thermal properties were evaluated. For dual modification, the ultrasonic modification was carried out first, followed by oxidation under the same conditions as an individual modification. After ultrasonic and ozone modification, the crystallinity of starch decreased, and the solubility increased to some extent. Starch's swelling power and solubility increased by 4.90% and 159%, respectively, after 10 min of ozone treatment. The tensile strength of the films modified by ozone for 10 min increased by 276%, the elongation at break increased by 72.5%, the water contact angle of the films modified by ozone increased by 154%, and the water vapor permeability decreased by 34.7%. Compared with the natural and single-modified starch films, the dual-modified ones had lower water vapor transmittance, moisture absorption rate, and higher transparency. The water vapor permeability decreased by 32.2%, and the transparency increased by 73.7%. The modification in this study had little effect on the solubility of the films.

Evaluation the Potential of Onion/Laponite Composites Films for Sustainable Food Packaging with Enhanced UV Protection and Antioxidant Capacity.

Agro-industrial residues have attracted attention for their applications in the field of biodegradable packaging. Recently, our research group has developed onion-based films with promising properties for this type of application due to their non-toxicity, biocompatibility and biodegradability. Therefore, in this study, we investigated the effect of Laponite clay concentration on the physicochemical and antioxidant properties of the onion-based films, which were prepared by a casting method. The XRD and FTIR data confirm the presence of the mineral clay in the onion-based films. These findings are consistent with those obtained from FE-SEM analysis, which revealed the presence of typical Laponite grains. In terms of wettability, the results show that the clay decreases the hydrophilic character of the material but slightly increases the water vapor permeation. Optical characterization revealed that the materials exhibited zero transmittance in the UV region and increased opacity in the visible region for composites containing 5% and 10% Laponite. Furthermore, the antioxidant test demonstrated higher antioxidant potential in the composites compared to the pure films. Consequently, these results suggest that the formation of Laponite and onion composites could be an essential strategy for developing natural polymers in the field of food contact packaging.

Studying the performance of a pilot scale vacuum-based membrane dehumidifier

Research on vacuum-based membrane dehumidification (VMD) has gained significant traction due to it being an efficient isothermal and eco-friendly process. However, most research works are focused on studying well-defined lab-scale membrane dehumidifiers. Therefore, key results on larger-size membrane dehumidifiers are far and few. In this work, a large-scale pilot-scale vacuum membrane prototype is developed and tested for the purpose of achieving high-performing air dehumidification in tropical climate conditions. The membrane prototype comprises 78 m2 of a flat-sheet composite membrane which possesses a high water vapor permeance and selectivity. It is able to remove 25 kg/h of water vapor from input humid air with a dehumidification COP of 2. This COP is much higher than that of a conventional desiccant dehumidifier and reaches 85% of the theoretical COP limit of a single stage pumping vacuum membrane dehumidifier. It is expected that a dehumidification COP of up to 16 can be achieved when this membrane prototype is coupled with a pumping-condensing system with high operating efficacy. The developed VMD system has highly stable performance in 8-week operation test.

Magnetic resonance imaging of water vapor absorption in simulated corrugated board

Water vapor absorption into a multi-layer simulated corrugated board structure was investigated using magnetic resonance imaging (MRI). Humidity and other ambient conditions considerably affect the strength and durability of corrugated board, and through creep, collapse of the corrugated board structures at unexpectedly low load levels. Currently, water vapor permeation and absorption are investigated with methods that do not elucidate the behavior of individual sheet layers in corrugated board. With MRI, signal intensity changes caused by water absorption can be spatially located and identified, providing a promising tool for the assessment of internal changes in a board, and its interaction with humidity. In this work, simulated corrugated board assemblies, consisting of alternating straight layers of linerboard and fluting material, were constructed, subjected to one-sided high humidity environment and periodically MR imaged to obtain temporal information on water accumulation at high relative humidity. It was observed that, in general, the fluting layers would exhibit higher signal intensities sooner, and by extension, higher water accumulation, when compared to the linerboards. The presented study provides insight into the behavior of paperboards in a double-wall corrugated board structure while under constant high humidity. In the future, actual corrugated board samples could be investigated in periodically fluctuating relative humidity and under constant stress to obtain information on the mechanosorptive creep.

Antimicrobial hydrocolloid composite sponge with on-demand dissolving property, consisting mainly of zinc oxide nanoparticles, hydroxypropyl chitosan, and polyvinyl alcohol

Abstract Effective anti-infection prophylaxis for chronic wounds can reduce the risk of wound infection and improve healing rates. The use of good anti-infection wound dressings is particularly important. In this paper, an antimicrobial composite hydrocolloid sponge dressing with zinc oxide nanoparticles, hydroxypropyl chitosan, and polyvinyl alcohol as the main components was prepared using freeze-drying of the formulated suspensions. The characterizations by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were performed; the antibacterial activity was determined; the on-demand dissolving properties were evaluated; and the basic properties such as porosity, vapor permeability, and water absorption were measured. The results showed that, when the mass ratio of HPCs/PVA was 6:4, the porosity, the steam permeability, the water absorption ratio, and dynamic complete dissolving time in 1 % acetic acid aqueous solution, respectively, reached the optimum value of 63.2 %, 57.7 %, 54.4, and 35 min. Antibacterial activity experiments showed that the sponges significantly inhibited Staphylococcus aureus, Escherichia coli, and Candida albicans. In conclusion, the above results indicate that the prepared hydrocolloid composite sponge has good air permeability, water absorption, antibacterial activity, and on-demand dissolving property and has potential applications in anti-infection treatment of hypo-exudative chronic wounds and pressure sore prevention.

From Bioresources to Thermal Insulation Materials: Synthesis and Properties of Two-Component Open-Cell Spray Polyurethane Foams Based on Bio-Polyols from Used Cooking Oil.

Open-cell spray polyurethane foams are widely used as highly efficient thermal insulation materials with vapor permeability and soundproofing properties. Unfortunately, for the production of commercial foams, mainly non-renewable petrochemical raw materials are used. The aim of this study was to determine the possibility of completely replacing petrochemical polyols (the main raw material used in the synthesis of polyurethanes, alongside isocyanates) with bio-polyols obtained from used cooking oils, classified as waste materials. The research consisted of three stages: the synthesis of bio-polyols, the development of polyurethane foam systems under laboratory conditions, and the testing of developed polyurethane spray systems under industrial conditions. The synthesis of the bio-polyols was carried out by using two different methods: a one-step transesterification process using triethanolamine and a two-step process of epoxidation and opening oxirane rings with diethylene glycol. The obtained bio-polyols were analyzed using gel chromatography and nuclear magnetic resonance spectroscopy. The developed polyurethane foam formulations included two types of fire retardants: halogenated tris(1-chloro-2-propyl) phosphate (TCPP) and halogen-free triethyl phosphate (TEP). In the formulations of polyurethane systems, reactive amine catalysts were employed, which become incorporated into the polymer matrix during foaming, significantly reducing their emission after application. The foams were manufactured on both a laboratory and industrial scale using high-pressure spray machines under conditions recommended by commercial system manufacturers: spray pressure 80-100 bar, component temperature 45-52 °C, and component volumetric ratio 1:1. The open-cell foams had apparent densities 14-21.5 kg/m3, thermal conductivity coefficients 35-38 mW/m∙K, closed-cell contents <5%, water vapor diffusion resistance factors (μ) <6, and limiting oxygen indexes 21.3-21.5%. The properties of the obtained foams were comparable to commercial materials. The developed polyurethane spray systems can be used as thermal insulation materials for insulating interior walls, attics, and ceilings.