Poly Propylene Oxide Research Articles

On the Structural and Molecular Properties of PEO and PEO-PPG Functionalized Chitosan Nanoparticles for Drug Delivery.

Chitosan nanoparticles (CS-NPs) are currently under investigation for a wide range of applications in nanomedicine. We investigated the structural, morphological, and molecular properties of CS-NPs synthesized via ionic gelation and designed specifically for drug delivery. The CS-NPs were prepared at concentrations ranging from 0.25 to 1.0% w/v. The 1.0% w/v CS-NPs were also functionalized with polyethylene oxide (PEO) alone and with a diblock copolymer of PEO and polypropylene glycol (PPG). The average nanoparticle size determined from TEM imaging is in the 11.3 to 14.8 nm range. The XRD and TEM analyses reveal a semi-crystalline structure with a degree of crystallinity dependent upon the nature of CS-NP functionalization. Functionalizing with PEO had no effect, whereas functionalizing with PEO-PPG resulted in a significant increase in the crystallinity of the 1.0% w/v CS-NPs. Additionally, the CS/TPP concentration (CS:TPP fixed at a 1:1 ratio) did not impact the degree of crystallinity of the CS-NPs. FTIR analysis confirmed the incorporation of TPP with CS and an increase in hydrogen bonding in more crystalline CS-NPs.

Highly Durable Silicone-Based Elastomers Achieved Through the Synergy of Bi-Incompatible Soft Segments and Multi-Scale Hydrogen Bonds.

Developing a silicone elastomer with high strength, exceptional toughness, good crack tolerance, healability, and recyclability, poses significant challenges due to the inherent trade-offs between these properties. Herein, the design of silicone-based elastomers with a nanoscopic microphase separation structure and comprehensive mechanical properties is achieved by combining bi-incompatible soft segments and multi-scale hydrogen bonds. The formation of multi-scale hydrogen bonds involving urethane, urea, and 2-ureido-4[1H]-pyrimidinone (UPy) facilitates efficient reversible crosslinking of the synthesized polymer containing thermodynamically incompatible poly(dimethylsiloxane) (PDMS) and poly(propylene glycol) (PPG). The dynamic dissociation and recombination of hydrogen bonds, coupled with the forced compatibility and spontaneous separation of bi-incompatible soft segments, can effectively dissipate energy, particularly in the crack region during the stretching process. The obtained silicone-based elastomer exhibits a high break strength of 8.0 MPa, good elongation at break of 1910%, ultrahigh toughness of 67.8 MJ m-3, and unprecedented fracture energy of 31.8 kJ m-2 while maintaining their thermal stability, hydrophobicity, healability, and recyclability. This resilient and long-lasting silicone-based elastomer exhibits significant potential for use in flexible electronic devices.

Atmospheric pressure field desorption-trapped ion mobility-mass spectrometry coupling

While field ionization (FI) and field desorption (FD) are established soft vacuum ionization methods in mass spectrometry (MS), the technique of atmospheric pressure field desorption (APFD) has only recently been added to the repertoire. Similar to FI and FD, APFD can yield both positive even-electron ions of highly polar or ionic compounds and positive molecular ions, M+•, e.g., of polycyclic aromatic compounds. Thus, a dedicated APFD source assembly has been constructed and demonstrated to allow for robust APFD operation. This device also enabled observation of the emitter during operation and allowed for resistive emitter heating, thereby speeding up the desorption of the analytes and expanding the range of analytes accessible to APFD. While initial work was done using a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer, the new APFD source offered the flexibility to also be used on a trapped ion mobility-quadrupole-time-of-flight (TIMS-Q-TOF) instrument, and thus, it would be possible to be mounted to any Bruker mass spectrometer featuring an atmospheric pressure (AP) interface. Operating an APFD source at a TIMS-Q-TOF instrument called for the exploration of the combined use of APFD and TIMS. Here, operation, basic properties, and capabilities of this new atmospheric pressure field desorption-trapped ion mobility-mass spectrometry (APFD-TIMS-MS) coupling are described. APFD-TIMS-MS is employed for the separation of individual components of oligomers and for the accurate determination of their collision cross section (CCS). This work describes the application of APFD-TIMS-MS on poly(ethylene glycol) forming [M + Na]+ ions by cationization and on an amine-terminated poly(propylene glycol) yielding [M + H]+ ions. Some compounds forming molecular ions, M+•, by field ionization such as [60]fullerene and a mixture of four polycyclic aromatic hydrocarbons (PAHs) are examined. In APFD-TIMS-MS, the limits of detection (LODs) of fluoranthene and benzo[a]pyrene M+• ions are determined as ≈100 pg and <1 pg, respectively. Finally, [60]fullerene is analyzed by negative-ion APFD-TIMS-MS where it yields a molecular anion, M−•.Graphical abstract

Relation of bubble size, grade and recovery in the copper flotation systems

In recent years, studies have shown that bubble structure, which is affected by reagent types, dosages, and particle size, is closely related to flotation performance. In contrast to two-phase systems, there is very limited information regarding bubble size in three-phase systems. To this aim, we investigated the relationship between bubble size and flotation performance with two different copper ores. Firstly, the surface tension and bubble size measurements were carried out in two-phase systems with Methyl isobutyl carbinol, and Polypropylene glycol methyl ether. Then the bubble size measurements were performed in three-phase systems at laboratory and industrial scales. The results showed that surface tension decreased with higher frother amounts and higher pHs. Although remarkable decreases in bubble size were observed with increasing frother amount, a direct relationship between surface tension and bubble size was not observed. However, pH affected the behavior of the frother, resulting in smaller bubble sizes at pH 12 compared to pH 7. Similarly, the three-phase laboratory tests showed that higher amount of frother caused a reduction in the bubble size and the copper grade. Increasing the amount of collector also caused the bubble size and copper grade to decrease, but the frothers were more effective in bubble size reduction. Compared to the two-phase, in the three-phase study bubble size was notably bigger due to the presence of a collector and solid. In the plant scale, smaller bubble size and higher grade were obtained compared with the laboratory scale due to presence of cleaning circuit measurements. The froth phase properties were also affected by the ore types due to properties such as size and hydrophobicity of the various mineral species present.

Effect of frother on dynamic detachment of rising bubble-coarse particle aggregates at gas-liquid interface

In the flotation process, the bubble-coarse particle aggregates easily undergo detachment at the gas-liquid interface, resulting in low mineral recovery. This paper tested the variation rule of surface tension with a concentration in the solution of four alcohols frother, namely, n-pentanol (NPA), methyl isobutyl carbinol (MIBC), 2-octanol, and polypropylene glycol (PPG). The effects of frothers on the motion characteristics of rising bubble-coarse particle aggregates and the dynamic detachment of aggregates at the gas-liquid interface were investigated separately using a high-speed dynamic camera system and a dynamic detachment device. The results showed that the solution surface tension decreased and then tended to be stabilized with the increase of frother concentration. Under the same concentration, the stronger the surface activity of the frother, the smaller the rising velocity of the bubble-coarse particle aggregates, and the more stable the motion state of the aggregates, with a smaller velocity fluctuation. The lower rising velocity reduced the particle detachment probability when aggregates collided with the gas-liquid interface. The merger time of the bubble-coarse particle aggregates was extended with the improved surface activity of the frother, increasing by more than 1 s compared to the solution without the frother. The study will contribute to effectively reduce the dynamic detachment probability of bubbles-coarse particle aggregates at the gas-liquid interface by selecting the type and concentration of frothers, meanwhile optimizing the reagent regime to enhance the coarse particle flotation recovery in the practical production process.

Safety assessment of the substance 'phosphorous acid, triphenyl ester, polymer with 1,4-cyclohexanedimethanol and polypropylene glycol, C10-16 alkyl esters', for use in food contact materials.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the substance 'phosphorous acid, triphenyl ester, polymer with 1,4-cyclohexanedimethanol and polypropylene glycol, C10-16 alkyl esters', when used as an additive in all types of polyolefins. The substance is a polymer containing ≤ 13% w/w of a low molecular weight fraction (LMWF, < 1000 Da). A polyethylene sample with 0.15% w/w of the substance was used in a comprehensive set of migration tests with food simulants. The specific migration was up to 0.014 and 0.023 mg/kg in 4% acetic acid and 10% ethanol, respectively. Migration into olive oil was estimated by the Panel to be up to 5.3 mg/kg under worst-case conditions of use. The migrating LMWF species were comprehensively identified. Those without phosphorous were either without alerts for genotoxicity or listed in Regulation (EU) 10/2011 with worst-case migrations well below their respective specific migration limits. Toxicological studies were performed using phosphite and phosphate versions of the substance enriched in its LMWF. The substance does not raise a concern for genotoxicity. From a repeated dose 90-day oral toxicity study in rats with a 50:50 phosphite:phosphate blend, the Panel identified a NOAEL of 250 mg/kg bw per day for each component of the blend. No delayed neurotoxicity in hens was observed. The CEP Panel concluded that the substance does not raise a safety concern for the consumer if its LMWF is not higher than 13% w/w, if it is used at up to 0.15% w/w in polyolefin materials and articles intended for contact with all food types, except for infant formula and human milk, for long-term storage at room temperature and below, after hot-fill and/or heating up to 100°C for up to 2 h, and if its migration does not exceed 5 mg/kg food.

Aqueous biphasic systems developed with deep eutectic solvents and polymer for the efficient extraction of pigments from beverages

Novel aqueous biphasic systems (ABSs) developed with benzyl-based quaternary ammonium salts-deep eutectic solvents (DESs) and polypropylene glycol (PPG) were herein proposed. The liquid-liquid equilibrium and the partitioning behavior of pigments in the systems were addressed. The results suggested that the shorter the carbon chain length of the DES, the easier to form two phases. The analysis of mixed samples showed that the selective separation was achieved in the ABSs, including 99.47% of tartrazine in the DES-rich phase and 98.47% of sudan III in the PPG-rich phase. Additionally, the systems were successfully applied to the extraction of pigments from the actual beverage samples with recoveries ranging from 93.43% to 102.15%. Furthermore, the study on the separation mechanism indicated that the hydrogen bonding played a significant role in the separation process. All the above results highlight the proposed DES/polymer-based ABSs have great advantages in selective and high-performance separation of pigments from beverages.

Synthesis of PEG-Polycycloether Block Copolymers: Poloxamer Mimics Containing a Rigid Helical Block.

Poloxamers are amphiphilic block copolymers consisting of poly(ethylene glycol) (PEG) and poly(propylene glycol) segments. Their self-assembly and interfacial properties are tied to the relative hydrophilicity and hydrophobicity of each block and can therefore be adjusted by changing block lengths. Here, a series of PEG-polycycloether block copolymers is synthesized that have the same structure as a poloxamer, but they encompass a rigid polycyclic backbone as the hydrophobic block. A variety of polymer structures are synthesized, for example diblock or triblock architectures, with/without olefinic units, atactic or isotactic backbone, and different block lengths. Due to their amphiphilicity, self-assembly into spherical aggregates (diameters ranging from 64 to 132nm) at low concentrations (critical aggregation concentration as low as 0.04mgmL-1) is observed in water. Low surface tensions (as low as 26.7 mNm-1) are observed as well as the formation of stable high internal phase emulsions (HIPEs) irrespective of the oil/water ratio. This contrasts with the properties of the commonly used poloxamers P188 or P407 and illustrates the significance of the rigid polycycloether block. These new colloidal properties offer new prospects for applications in emulsion formulations for biomedicine, cosmetics, and the food industry.

Green Extraction Strategy Using Bio-Based Aqueous Biphasic Systems for Polyphenol Valorization from Grape By-Product.

Polyphenols are natural compounds with enhanced antioxidant properties. They are present in relatively high concentrations in fruit/vegetable by-products. Therefore, there is a need for the development of efficient and cost-effective methods for the separation and purification of these valuable compounds. Traditional extraction with organic solvents needs to be switched to novel methods that are more efficient, with reduced extraction times and low consumption of organic solvents. Aiming at developing sustainable processes for the separation and purification of phenolic compounds, we used three model compounds, namely resveratrol, quercetin, and gallic acid, to investigate ionic liquid-based aqueous biphasic systems (IL-ABSs) formed by cholinium-based IL in combination with polypropylene glycol with a molecular mass of 400 g/mol (PPG400). The ABS composition in the two-phase region was selected according to a previously determined phase diagram. Extraction studies indicated the preferential partition of resveratrol and quercetin toward the hydrophobic PPG-rich phase that is mainly dominated by its hydrophobic nature and the strong salting-out effect of ILs. On the other hand, due to its considerably hydrophilic nature, gallic acid preferentially migrates toward the IL phase. The achieved results from grape stem extract demonstrated high extraction efficiencies of cholinium dihydrogen phosphate (~99% for resveratrol for the PPG phase and 78% for gallic acid for the IL phase), with considerable selectivity, demonstrating promising outcomes for potential applications.

Estimation of Ionic Impurities in Poly(propylene Glycol) Diacrylate Monomers/Liquid Crystal E7 Mixtures Using Dielectric Spectroscopy

The study investigated the effect of the molecular weight of three difunctional poly(propylene glycol) diacrylates on the temperature-dependent ionic conductivity of these monomers and their blends with an eutectic nematic liquid crystal mixture (E7). The results revealed two distinct regions. At low temperatures, ionic conduction can be described by the Vogel–Tamman–Fulcher (VTF) equation, while at high temperatures, the conductivity data follow the prediction of the Arrhenius model. The Arrhenius and VTF parameters and their corresponding activation energies were determined using the least squares method. In addition, a conductivity analysis based on an ionic hopping model is proposed. Estimates of ion concentrations and diffusion constants were calculated. It was found that both the ionic concentration and the diffusion constant decrease with the increase in the molecular weight of the monomers. The static dielectric permittivity decreases in the following order: TPGDA, PPGDA540, and PPGDA900. This can be explained by the higher dipole moment of TPGDA, which is caused by an enhanced volume density of carbonyl groups.

Modification of Biodegradable Polymer Nanofibers for Cartilage Tissue Engineering Applications: A Review

Tissue engineering is the use of a combination of cells, engineering and materials methods, and suitable biochemical and physiochemical factors to improve or replace biological functions at the injured site. The designing of a biomaterial that can mimic the three-dimensional tissues in vivo is still challenging. Biodegradable polymers are used for the development of tissue engineering constructs in the form of sponges, films, and macroporous scaffolds, which do not influence cell fate processes such as cell differentiation, migration, and proliferation. Biodegradable polymer nanofibers fabricated by electrospinning have gathered great attention in tissue engineering applications. The electrospun materials have a nanofibrous morphology that is closest to the natural extracellular matrix (ECM). The electrospun material is composed of three-dimensional networks of nanosized fibrous materials that mimic an extracellular matrix such as collagen, elastin, and keratin. These polymers fabricated in the form of fibers in nanosize cause a more favorable microenvironment for cells. We prepared the PLGA/PPG (polylactic-co-glycolic acid/polypropylene glycol) nanofibers by electrospinning technique. PLGA (85:15)/PLGA (75:25) nanofibers are hydrophobic, which can be minimized by the addition of PPG to give better hydrophilicity for cell adhesion for tissue engineering constructs. The morphology of the electrospun fibers of the composite of PLGA and PPG was observed using scanning electron microscopy (SEM). The results proved that the small amount of polypropylene glycol polymer to the polylactic-co-glycolic acid (PLGA 85:15) drastically improves the hydrophilicity of the electrospun nanofibers. The addition of a small amount of hydrophilic polymer to the biodegradable hydrophobic polymer increases the hydrophilic property and can be used for nanofiber-based tissue engineering constructs. In addition, the biomimetic approach for tissue engineering scaffolds for cartilage repair has been discussed.

Molecular Doped Biodegradable Triboelectric Nanogenerator with Optimal Output Performance

AbstractBiodegradable polymers (BPs)‐based triboelectric nanogenerators (TENGs) have advantages, including biocompatibility and biodegradability. However, biodegradable TENGs (BD‐TENGs) possess relatively low output performance, limiting their application due to the small differences in triboelectric polarities for most BPs. Molecular doping is a simple and effective method in altering the triboelectric polarity of triboelectric materials and improving the output performance of BD‐TENGs. However, there is a lack of laws and mechanism about the differences in triboelectric polarities of different doped molecules, especially of molecules with biodegradability and biocompatibility. Here, kinds of doping molecules are selected for doping in tribopositive and tribonegative materials, respectively, and their triboelectric polarities and related laws are researched. In particular, the output performance of BD‐TENG is improved several times by doping small amounts of poly (propylene glycol) (PPG) and ethyl cellulose (EC), with enhanced resolution in abnormal respiratory signal monitoring. This work not only provides theoretical guidance for the selection of triboelectric molecules but also conducts in‐depth research in molecular‐level triboelectric mechanisms.

Study on the effect of chain extenders on aliphatic polyurethane and its application

AbstractThermoplastic polyurethane (TPU) has been applied to high‐performance laminated glass depending on its high impact strength and bonding properties. The utilization of various polyurethane molecular structures in laminated glass is scarcely reported. The selection and application of chain extenders are crucial for TPU performance. In this work, aliphatic polyurethane film with high strength has been successfully synthesized, incorporating chain extender of poly(propylene glycol) bis(2‐aminopropyl ether) (PEA230). The films with melting point above 80°C were prepared by adjusting the proportion of dimethylglyoxime (DMG), while simultaneously monitoring the thermal behavior of the samples by DMA. Results indicate that combining PEA230 and DMG in a 1:1 molar ratio yields the hydrogen bonding degree of 85.77%, toughness of 43.14 MJ m3, and shear stress of 1.8 MPa for the polyurethane film. Subsequently, laminated glasses based on the polyurethane film with different thermal properties were constructed successfully, and their super strong impact resistance was confirmed through falling ball impact experiments.

Blood compatibility of poly(propylene glycol diester) and its water structure observed by differential scanning calorimetry and 2H-nuclear magnetic resonance spectroscopy

Recently, we applied solution 2H-nuclear magnetic resonance spectroscopy (2H NMR) to analyze the water (deuterium oxide, D2O) structure in several biopolymers at ambient temperature. We established that polymers with good blood compatibility (i.e. poly(2-methoxyethyl acrylate) (PMEA)) have water observed at high magnetic fields (upfield) compared with bulk water. Polymers containing poly(propylene glycol) (PPG) or poly(propylene oxide) (PPO) exhibit good compatibility; however, the reason for this remains unclear. In addition, reports on the blood compatibility of PPO/PPG are limited. Therefore, PPG diester (PPGest) was prepared as a model polymer, and its blood compatibility and water structure were investigated. PPGest exhibited excellent blood compatibility. The water in PPGest was observed upfield by 2H NMR, and it was defined as non-freezing water via differential scanning calorimetry. Based on these observations, the relationship between the blood compatibility and water structure of PPGest is discussed by comparing with those of PMEA, and the reason for the good performance of PPG/PPO-based polymers is discussed.

Toxicological Aspects Associated with Consumption from Electronic Nicotine Delivery System (ENDS): Focus on Heavy Metals Exposure and Cancer Risk.

Tobacco smoking remains one of the leading causes of premature death worldwide. Electronic Nicotine Delivery Systems (ENDSs) are proposed as a tool for smoking cessation. In the last few years, a growing number of different types of ENDSs were launched onto the market. Despite the manufacturing differences, ENDSs can be classified as "liquid e-cigarettes" (e-cigs) equipped with an atomizer that vaporizes a liquid composed of vegetable glycerin (VG), polypropylene glycol (PG), and nicotine, with the possible addition of flavorings; otherwise, the "heated tobacco products" (HTPs) heat tobacco sticks through contact with an electronic heating metal element. The presence of some metals in the heating systems, as well as in solder joints, involves the possibility that heavy metal ions can move from these components to the liquid, or they can be adsorbed into the tobacco stick from the heating blade in the case of HTPs. Recent evidence has indicated the presence of heavy metals in the refill liquids and in the mainstream such as arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), copper (Cu), and lead (Pb). The present review discusses the toxicological aspects associated with the exposition of heavy metals by consumption from ENDSs, focusing on metal carcinogenesis risk.

Photopolymerization Pattern of New Methacrylate Cellulose Acetate Derivatives.

Polymeric photocrosslinked networks, of particular interest in the design of materials with targeted characteristics, can be easily prepared by grafting light-sensitive moieties, such as methacrylates, on polymeric chains and, after photochemical reactions, provide materials with multiple applications via photopolymerization. In this work, photopolymerizable urethane-methacrylate sequences were attached to free hydroxyl units of cellulose acetate chains in various proportions (functionalization degree from 5 to 100%) to study the properties of the resulting macromolecules and the influence of the cellulosic material structure on the double bond conversion degree. Additionally, to manipulate the properties of the photocured systems, the methacrylate-functionalized cellulose acetate derivatives were mixed with low molecular weight dimethacrylate derivatives (containing castor oil and polypropylene glycol flexible chains), and the influence of UV-curable composition on the photopolymerization parameters being studied. The achieved data reveal that the addition of dimethacrylate comonomers augmented the polymerization rates and conversion degrees, leading to polymer networks with various microstructures.

DFT study on the polyol sacrificial agents for improved clay tolerance of polycarboxylate superplasticizers

With the gradual scarcity of high-quality sand and gravel resources, the increasing mud content in concrete aggregates could strongly adsorb on polycarboxylate superplasticizers (PCE), greatly reducing their working performance. Modifying the molecular structure of PCE or compounding sacrificial agents can effectively improve the tolerance to clay minerals. In this article, using different small molecule polyols and polypropylene glycol (PPG) as examples, density functional theory (DFT) was employed to simulate the adsorption between clay minerals and hydration products. This exploration aims to further understand the anti-clay performance of various sacrificial agents from the perspective of adsorption energy. Ca-montmorillonite (CaMMT) exhibits the lowest adsorption energy among different clay minerals, making it the preferred site for sacrificial agent adsorption. With an increase in hydroxyl number, the adsorption energy between polyol sacrificial agents and montmorillonite decreases. Among polymeric polyols, the adsorption energy between PPG 600 and montmorillonite is the lowest (-10.86 eV), indicating superior anti-clay performance by preferentially occupying active sites on montmorillonite. As the interlayer spacing of montmorillonite increases, the adsorption energy between PPG 600 and montmorillonite initially decreases and then increases, reaching the lowest value at c=15.5 Å. There are more electron transfers (0.858) compared to the electron gain and loss, confirming more interaction between the sacrificial agents and montmorillonite at 15.5Å. This article also provides a crucial theoretical basis for the structural design of anti-clay sacrificial agents, offering insights into addressing compatibility issues between PCEs and clay minerals.

Design of 3D-Photoprintable, Bio-, and Hemocompatible Nonisocyanate Polyurethane Elastomers for Biomedical Implants.

Polyurethanes (PUs) have adjustable mechanical properties, making them suitable for a wide range of applications, including in the biomedical field. Historically, these PUs have been synthesized from isocyanates, which are toxic compounds to handle. This has encouraged the search for safer and more environmentally friendly synthetic routes, leading today to the production of nonisocyanate polyurethanes (NIPUs). Among these NIPUs, polyhydroxyurethanes (PHUs) bear additional hydroxyl groups, which are particularly attractive for derivatizing and adjusting their physicochemical properties. In this paper, polyether-based NIPU elastomers with variable stiffness are designed by functionalizing the hydroxyl groups of a poly(propylene glycol)-PHU by a cyclic carbonate carrying a pendant unsaturation, enabling them to be post-photo-cross-linked with polythiols (thiol-ene). Elastomers with remarkable mechanical properties whose stiffness can be adjusted are obtained. Thanks to the unique viscous properties of these PHU derivatives and their short gel times observed by rheology experiments, formulations for light-based three-dimensional (3D) printing have been developed. Objects were 3D-printed by digital light processing with a resolution down to the micrometer scale, demonstrating their ability to target various designs of prime importance for personalized medicine. In vitro biocompatibility tests have confirmed the noncytotoxicity of these materials for human fibroblasts. In vitro hemocompatibility tests have revealed that they do not induce hemolytic effects, they do not increase platelet adhesion, nor activate coagulation, demonstrating their potential for future applications in the cardiovascular field.

Development of PU foam dressings loaded with extract of Plectranthus amboinicus for burn wound healing

Objective To develop Plectranthus amboinicus extract loaded Polyurethane foam dressing for burn wound healing. Significance Plectranthus amboinicus is traditionally used as an anti-inflammatory and wound-healing agent. Its incorporation in a PU foam dressing will offer the dual benefits of foam dressing as well as the healing potential of P. amboinicus. Methods PU foam dressings were prepared and loaded with P. ambionicus leaf extract (PAE). The dressings were prepared with varying concentrations (0.5–2%) of extract along with Toluene diisocyanate, polypropylene glycol (PPG), and liquid paraffin. The dressings were characterized by Scanning Electron Microscopy and evaluated for Moisture Vapor Transmission Rate, absorption rate, porosity, and mechanical strength followed by in vivo burn wound-healing studies in comparison to a marketed dressing. Results The MVTR was found to be optimum in formulations FD2-FD4 with values ranging from 2068.06 ± 0.99 to 2095.00 ± 0.25 g/m2/day. Absorption rate was found to be between 1.27 ± 0.01, 1.31 ± 0.00, and 1.30 ± 0.02 g/cm2 for formulations FD2-FD4. Formulations FD1, FD2, FD3, FD4 showed better porosity when compared to other formulations. Formulation FD4 was further characterized by micro-CT and a porosity of 46.32% was obtained. Tensile strength measurement indicated that the selected formulations were flexible enough to withstand regular handling during dressing changes. Acute dermal irritation performed on rabbits showed no irritation, erythema, eschar, and edema. In vivo wound-healing studies performed on albino wistar rats showed that the FD4 formulation has better wound healing property. Conclusion Plectranthus ambionicus-loaded PU foam dressing demonstrated promising burn wound-healing potential

Dielectric Design of High Dielectric Constant Poly(Urea-Urethane) Elastomer for Low-Voltage High-Mobility Intrinsically Stretchable All-Solution-Processed Organic Transistors.

Stretchable organic transistors for skin-like biomedical applications require low-voltage operation to accommodate limited power supply and safe concerns. However, most of the currently reported stretchable organic transistors operate at relatively high voltages. Decreasing their operational voltage while keeping the high mobility still remains a key challenge. Here, the study presents a new dielectric design to achieve high-dielectric constant poly(urea-urethane) (PUU) elastomer, by incorporating a flexible small-molecular diamine crosslinking agent 4-aminophenyl disulfide (APDS) into the main chain of (poly (propylene glycol), tolylene 2,4-diiso-cyanate terminated) (PPG-TDI). Compared with commercial elastomers, the PUU elastomer as dielectric of the stretchable organic transistors shows the outstanding advantages including lower surface roughness (0.33nm), higher adhesion (45.18 nN), higher dielectric constant (13.5), as well as higher stretchability (896%). The PUU dielectric enables the intrinsically stretchable, all-solution-processed organic transistor to operate at a low operational voltage down to -10V, while preserving a substantial mobility of 1.39 cm2V-1s-1. Impressively, the transistor also demonstrates excellent electrical stability under repeated switching of 10000 cycles, and remarkable mechanical robustness when stretched up to 100%. The work opens up a new molecular engineering strategy to successfully realize low-voltage high-mobility stretchable all-solution-processed organic transistors.