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AbstractElectrochromic devices (ECDs) have broad application prospects in smart windows, low-power displays, anti-glare rearview mirrors, and so on. The electrolyte layer is one of the crucial components of ECDs acting as an interface layer between two electrodes to provide ions transport. Conventional liquid electrolytes have disadvantages of easy leakage, low safety and complex encapsulation, while inorganic solid electrolytes (ISEs) have very poor room temperature conductivity. Polymer electrolytes are composites consisting of polymeric matrices, solvents, conductive salts and curing agents, including solid polymer electrolytes (SPEs), gel polymer electrolytes (GPEs) and composite polymer electrolytes (CPEs). They are widely used in ECDs because of their excellent ionic conductivity, superior electrochemical stability, high transparency and simplicity of processing. This review provides a detailed discussion of the types, mechanisms, characteristics and preparation methods of polymer electrolytes for ECDs. The latest research progresses in the design and application of CPEs based on poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF) and poly(vinyl alcohol) (PVA) are highlighted, and the potential applications of polymer electrolytes in the field of electrochromism are reviewed. Furthermore, the future development of polymer electrolytes in ECDs with stability, significant coloration efficiency and high ionic conductivity is discussed. [ABSTRACT FROM AUTHOR]

Polymer gel has been accepted as a useful tool for solving many sealing operations such as fluid loss control, enhanced oil recovery, water and gas shutoff, wellbore integrity, and well stimulation in the upstream of petroleum industry. In a previous study, we used acrylamide (AM), N,N'-Methylenebisacrylamide (MBA), xanthan (XC) and chromium acetate (Cr3+) to obtain ultra-high strength gel (USGel). Some interesting phenomena, such as the more than 10 times increase in gel strength by 0.05% Cr3+ and the counter-conventional decrease in gel strength by inorganic particles such as layered silicate materials (LSM), silicon dioxide nanoparticles (SiO2) and laponite (RDS), have not been well explained. In this paper, the gelation kinetics and mechanism of USGel were investigated mainly by bottle, DSC, infrared spectroscopy, and environmental scanning electron microscopy (ESEM) experiments, which explained that Cr3+ significantly increased the gel strength of USGel, while inorganic particles had a negative effect on the gel strength. The experimental results showed that Cr3+ preferentially cross-linked AM and XC than MBA, and the gelation rates of Cr3+-XC and Cr3+-AM were 107% and 92.9% faster than AM-MBA, respectively. It is speculated that the triple network structure and physical entanglement formed by AM-MBA, XC-Cr3+, and AM-Cr3+ are the main reasons for significant improvement of gel strength by Cr3+, and the cross-linking competition between LSM and Cr3+ and reduction of entanglement number are the main reasons for the significant reduction of gel strength by LSM. This paper provides new insights into the preparation of ultra-high strength gels and the usage of inorganic particles. [ABSTRACT FROM AUTHOR]

Polymer microgels are smart materials used to fabricate and encapsulate different enzymes. Encapsulation of enzymes in the polymer gel particles prolong their life span, enhance and tune their activity in biomedical field to prevent cell damage and make possible tunable drug delivery. Enzymes are natural catalysts and have prodigious ability to make the reaction kinetically feasible. Enzymes encapsulated polymer microgels gained much attention due to their synergistic properties. Here, different methods adopted for the synthesis of enzyme encapsulated polymer microgels, their properties, and classification based on responsive behavior have been described in detail. Applications of these enzyme encapsulated polymer microgels in sensing, catalysis, environmental remediation, useful product formation, and biomedical field to prevent disabilities have also been elaborated with future directions. [ABSTRACT FROM AUTHOR]

It is easier and cheaper to prevent forest fires than to extinguish them, therefore, the development of long-lasting and environmentally friendly fire-retarding materials is highly desirable to prevent the spread of forest fires. In this study, soluble carboxymethyl starch replaced insoluble carboxymethyl cellulose to improve the compressive strength of inorganic gel and overcome the weakness of fragility. When the concentration of polymer carboxymethyl starch and crosslinking agent aluminum citrate were 0.5% and 0.3%, respectively, the inorganic/organic composite gel showed the best comprehensive performance (including gelation time, water retention, seepage velocity and strength). Additionally, the antioxidant tannin was introduced into the inorganic/organic gel, which effectively inhibited the oxidation of wood flour, making its inhibition rate reached 23.1%, about twice that of pure inorganic gel. This is mainly attributed to the ability of tannin to inhibit the oxidation process of active groups, including carbon-oxygen, hydroxyl, and methyl of the wood powder, thereby enhancing the flame resistance of the composite gel. Probable mechanism of forest fire suppression by the antioxidant composite gel is proposed, which involves oxygen isolation, evaporative cooling, and chain reaction inhibition. [ABSTRACT FROM AUTHOR]

Fabrication of a suitable drug delivery system forms an attractive strategy to overcome the low bioavailability of quercetin. Poly(2-hydroxyethyl methacrylate–co-N-hydroxyethyl acrylamide), P(HEMA-co-HEAA) copolymer samples, and homopolymers of 2-hydroxyethyl methacrylate (PHEMA) and N-hydroxyethyl acrylamide (PHEAA) offer potential as quercetin delivery matrices owing to their favorable properties rendered in this study. Free radical polymerization applied under cryogenic conditions produced the polymer gels. The homopolymers and copolymers are noncytotoxic, porous, soft cryogels with surfaces resistant to protein and HCT-116 cancer cell adhesion. In vitro, quercetin release studies from samples reveal swelling-controlled, zero-order drug release at pH = 7.4 and 37 °C with high cumulative release percentages ranging from 92.03% to 94.82%. The durability of the cryogels and limited quercetin release at pH = 2.0 indicate that these cryogels are promising matrices for successfully delivering quercetin to the small intestine, where its primary absorption occurs. [ABSTRACT FROM AUTHOR]

The swelling properties of polyacrylonitrile gel prepared by the repeating cycle of freezing and thawing were examined, as its transient response toward the equilibrium swollen states varies with the variation of mixing ratio (r) of the immersion solvent which consisted of N, N–dimethylacetamide and benzene. Two experimental protocols were used; successive solvent exchanges were conducted in Protocol 1, and no solvent exchange but the varying of the volume of immersion solvent was conducted in Protocol 2. Also, the aging time was set between the end of the freezing and thawing cycle and the start of the swelling experiment. As a result, the equilibrium swelling ratio decreased with the increase in the aging time. Significant discrepancies for the transient responses were found for the immersion solvents between r ≤ 0.74 and r ≥ 0.78 both in Protocol 1 and 2, in which the elution of polyacrylonitrile molecules was related to the responses. A characteristic overshoot curve was observed in the swelling with r ≥ 0.78 in Protocol 2, which was also attributed to the polyacrylonitrile elution. The polymer solvent interaction parameter was calculated on the basis of the osmotic pressure equilibrium, which was associated with the interpretation of the transient response data. [ABSTRACT FROM AUTHOR]

The multiblock copolymers, which exhibit more complex block composition and sequences than those of di- or tri-block copolymers, have attracted more and more scientific interest and attention in the past years. The ABCBA linear pentablock terpolymer with block number of 5 is a representative model and starting point for investigating the self-assembly of multiblock copolymers, which is helpful for understanding the assembled structures and solution properties of biomacromolecules with complex sequence structures. Compared with AB diblock copolymers and ABC triblock terpolymers, the ABCBA pentablock terpolymers have more intricate morphologies and have better mechanical properties with similar morphologies. This review will mainly focus on ABCBA linear pentablock terpolymers and systematically summary the recent research progress in self-assembly of ABCBA linear pentablock terpolymers in bulk and solution as well as their potential applications in various technical fields including drug carriers, surface coatings, inorganic material templates, battery materials, and polymer gel. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotube hybrid polymer gel particles (MWCNTs-HPGP) were synthesized using the free radical polymerization approach to reduce water cut at first. The microstructure, particle size distribution, swelling characteristics, strength, and rheology of MWCNTs-HPGP were then studied. Subsequently, the migration and plugging properties of MWCNTs-HPGP were assessed at the core scale. The morphology of MWCNTs-HPGP was irregular with interpenetration networks, and MWCNTs-HPGP could expand by 48.2–94 times in brine with varying salinities (0 ∼ 20 × 104 mg/L NaCl), according to experimental results. After 60 d of age, MWCNTs-HPGP retained 95.2% of strength. Furthermore, the MWCNTs-HPGP dispersion solution's shearing thinning feature and good viscoelasticity supplied it with favorable injectivity and deep migrating capacity. In addition, when the matching coefficient (β, the ratio of MWCNTs-HPGP median particle size to the average pore diameter) was 1.06 and the flooding rate was 0.5 mL/min, MWCNTs-HPGP could efficiently plug large pores with a plugging efficiency ranging from 82.7% to 98.5%. All the experimental results demonstrated that MWCNTs-HPGP could be a potential candidate for deep profile control and displacement in high temperature and high salinity reservoirs. [ABSTRACT FROM AUTHOR]

A wide range of analytical strategies and approaches have been developed, accomplishing significant advances in searching for efficient, fast, reliable, sensitive, and accurate protocols for sample analysis in recent decades. Chemical sensors are also low-cost, portable, and ecologically friendly, making them a preferred method of choice for a broad spectrum of sample analysis in various matrices of complexity. Of particular interest are sensors based on fluorescent molecules, nanoparticles, nanoclusters, quantum dots, carbon nanotubes, molecularly imprinted polymers, sol-gels, dyes, porphyrins, ionic liquids, organized media, and fluorescent sensor arrays in microfluidic chips. This review highlights and provides concise and in-depth coverage of recent innovations, challenges, advances, and applications of a variety of fluorescence-based sensors for sample analysis between 2018 and 2022. Emphasis is placed on instrumentation design and the applications of sensors in analytical, environmental, pharmaceutical, agricultural, food, and forensic sample analysis. Recent innovations and the practical utility of fluorescent chemical sensors relevant to biological systems, biomedical sample measurements, and clinical diagnosis are extensively reviewed. Future directions and trajectories of fluorescent chemical sensors for various utilities, applications, and sample measurements are highlighted and discussed. [ABSTRACT FROM AUTHOR]

Compared with conventional polymer gels, nanocomposite gels have significant advantages in strength and temperature resistance. They can adapt to more severe reservoir environments and achieve the purpose of controlling water and increasing oil or temporarily plugging and diverting. Based on nanoparticles used in nanocomposite gels, nanocomposite gels can be divided into silica-based nanocomposite gels, nano-montmorillonite-based nanocomposite gels, layered silicate nanocomposite gels, laponite-based nanocomposite gels, CFA (coal fly ash)-based nanocomposite gels, and other nanocomposite gels. The researcher summarized the materials used in various nanocomposite gels (nanomaterials, main polymers, and crosslinking agents), mechanisms, excellent performance, and analyzed the shortcomings of various nanocomposite gels and current development trends. The results show that the research of nanocomposite gels needs to deal with the high temperature and high salinity oil and gas reservoir environment, and it is necessary to adopt environmentally friendly, easy-to-prepare and cheap materials. At the same time, more numerical simulation studies are needed for theoretical guidance. [ABSTRACT FROM AUTHOR]

We describe a mechanism of pre-transition process near the sol-gel transition temperature in the sol-phase of water solutions of rigid-chain polymers. During this process the water boundary layer is disordered, and voids are formed in it. The variation of density of the hydroxypropyl methylcellulose with temperature is measured experimentally for temperatures between 25 and 80 °C. The experiment supports the proposed mechanism. [ABSTRACT FROM AUTHOR]

In this work, gold nanoparticles (NPs) of 100 nm in size were added to the active layer of DSSC. The electrolyte is a gel polymer electrolyte (GPE) containing PEO, PhCh, TPAI, BMII, I2, DMF, EC, TBP, and GuSCN. The DSSCs have been characterized via J–V characteristics, IMVS, and IMPS measurements. On illumination at AM 1.5, the cell with 3 wt.% Au NP in the photoanode exhibits an η of 8.56% with Jscof 19.82 mA cm−2, Voc of 0.72 V and FF of 60%. The same cell also exhibited the lowest τtr of 7.32 ms and longest τrec of 115.33 ms. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSSCs) have been constructed using fluoride tin oxide (FTO) glass deposited with TiO2 and anthocyanin dye extracted from blackberries as the photoanode, platinum coated cathode, and gel polymer electrolytes (GPEs) comprising poly(vinyl alcohol) (PVA) dissolved in two different solvents, viz., dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). GPE employing DMF solvent exhibits the highest ambient conductivity of 14.05 mS cm−1. Charge transport properties of DSSCs were studied via intensity-modulated photocurrent spectroscopy (IMPS), intensity-modulated photovoltage spectroscopy (IMVS) and electrochemical impedance spectroscopy (EIS). The highest efficiency of 0.54% is recorded for DSSC with GPE containing DMF and TBP. [ABSTRACT FROM AUTHOR]

Gel polymer electrolytes with polyurethane acrylate (PUA) and tetrapropylammonium iodide (TPAI) have been prepared. The maximum conductivity of (4.95 ± 0.02)×10−5 S cm−1 was obtained after 35 wt.% TPAI is added to PUA (G5 electrolyte), dominated by the highest charge carrier mobility (µ). The perovskite solar cell (PSC) with G5 electrolyte displayed the highest power conversion efficiency of (0.206 ± 0.014)%, caused by the highest µ in electrolyte G5 that accelerates the electron transfer from the counter electrode to the ionized perovskite. This research proves that PUA can be exploited as a host polymer in polymer electrolytes for PSC applications. [ABSTRACT FROM AUTHOR]

This work aimed to fabricate alginate based in-situ gelling matrix of vildagliptin improved by calcium and carboxy methyl cellulose (CMC) for appropriate adjustment of the onset and duration of action. This easy-to-swallow thickened liquid preparation aimed to improve compliance for dysphagic or elderly diabetic patients. Vildagliptin dispersions containing alginate were fabricated in the presence or absence of calcium chloride to assess the effect of calcium ion, then a matrix containing 1.5% w/v of sodium alginate with calcium was further examined after the addition of CMC with different concentrations ranging from 0.1% to 0.3%. The viscosity, gelling forming property, Differential scanning calorimetry, and in-vitro drug release were assessed before monitoring the hypoglycemic effect of the selected formulation. In-situ gel matrixes were fabricated at gastric pH with and without calcium ions. The best formula concerning viscosity and the gel-forming property was achieved with higher CMC concentrations, which in turn decreased the rate of vildagliptin release in stimulated gastric pH. In-vivo results confirmed the extended hypoglycemic effect of the vildagliptin in-situ gelling matrix compared to the vildagliptin aqueous solution. This study represents a green polymeric-based in-situ gel as a liquid oral retarded release preparation intended for reducing dose frequency, easier administration of vildagliptin, and improving compliance in geriatric and dysphagic diabetic patients. [ABSTRACT FROM AUTHOR]

The formulation of a hybrid gel polymer electrolyte (HGPE) system comprising of polymethyl methacrylate (PMMA) and polylactic acid (PLA) as a hybrid host polymer doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) has been successfully prepared in this study with the introduction of an ionic liquid, namely 1-Ethyl-3-methylimidazolium chloride (EMIMCl). Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were used to investigate the structural features of HGPEs. The FTIR analysis revealed that the complexation changes the peak intensity at region C = O stretching, CH2 bending, and C-O stretching. Meanwhile, XRD showed that the addition of EMIMCl altered the HGPE properties and formed an amorphous structure. The prepared HGPE sample was examined for ionic conduction properties through electrical impedance spectroscopy (EIS). It shows that by adding an EMIMCl to the PMMA-PLA-LiTFSI HGPE has decreased the activation energy (Ea) and increased the ionic conductivity. The sample containing 15 wt.% has the lowest Ea value of 0.057 eV and the highest ionic conductivity at room temperature of 3.20 10−3 S cm−1. The itemperature dependence was studied in the temperature range from 303 K to 393 K, the HGPE systems were found to follow Arrhenius behavior. The effect of EMIMCl content had decreased the viscosity of HGPEs which led to the gel-like type behavior. The potential windows stability analysis revealed that the highest conducting sample was electrochemically stable up to 3.3 V versus Li/Li+, thus showing that the present electrolytes are promising to be applied as in Li-ions battery. [ABSTRACT FROM AUTHOR]

Oxidative stress caused by the harsh microenvironment after implantation of an artificial graft with mismatching mechanical properties usually triggers inflammation responses, which have adverse impacts on tissue regeneration. For coping with these problems, in this work, bioactive fibrous scaffolds were developed from specially synthesized carboxylated poly(ester urethane)urea (PEUU) and gelatin (Gel) by encapsulating pterostilbene (Pte) for the first time. The prepared electrospun membranes exhibited self-adaptable mechanical properties with high elasticity owing to the bonded electrospun fibers, cross-linking network between PEUU and Gel, and the inherent flexibility of the PEUU polymer in the fibrous matrix. The PEUU/Gel/Pte electrospun membrane containing 7% Pte could promote in vitro proliferation of human umbilical vein endothelial cells, and regulate vascular smooth muscle cells with excellent antioxidant properties via free radical scavenging. In vivo results in a rat subcutaneous implantation model further demonstrated the positive effect of the specially prepared PEUU/Gel/Pte scaffold on both normal cell growth and anti-inflammatory by promoting cellularization and polarizing macrophages toward the M2 phenotype. These PEUU/Gel/Pte electrospun membranes with adaptability benefit to tissue regeneration by modulating inflammation responses, especially applications in vascular regeneration. [ABSTRACT FROM AUTHOR]

Working fluid loss as well as formation damage is usually encountered as a big challenge during well completion and workover for fossil-fuel production. Polymer gel is widely used for wellbore plugging to isolate the working fluid and the reservoir for controlling fluid loss and protecting the reservoir. However, with the increasing number of ultra-high temperature well (>180 °C) operations, the thermal stability of the gel plug is increasingly required. In this paper, 1,2 dimethylimidazole (C5H8N2) is first used to prepare a gel plug. The effects of C5H8N2 on gel gelation at dynamic heating mode, viscosity, elasticity, thermal stability and temporary plugging performances are evaluated at 190 °C. It is found that the addition of C5H8N2 does not affect the gelation, while a slightly viscosity-reducing effect is exhibited. At 190 °C, the gel without C5H8N2 broke down within 4 hours and lost its temporary plugging performance, while the gel with 20% imidazole remained unbroken after 60 hours. For the fractured core (5 cm in length) plugging experiments, the addition of 15% C5H8N2 significantly increased the breakthrough pressure of gels from 0.2 MPa to 1.9 MPa compared to pure gels (without C5H8N2). The enhancement mechanism of C5H8N2 is investigated. Recommendations for the application of gels with C5H8N2 are given in the paper. This paper provides an avenue for the development of gel plug to deal with wellbore temporary plugging jobs in ultra-high temperature fractured reservoirs. [ABSTRACT FROM AUTHOR]

Polymer gels are potential plugging agents for gas mobility control in flue gas flooding reservoirs. However, the influence of flue gas on performances of polymer gels have not been clearly clarified so far. In this study, the effect mechanism of flue gas on chromium acetate/partially hydrolyzed polyacrylamide (HPAM) gel system has been elucidated in detail. Dynamic light scattering (DLS) and polymer rheological tests demonstrated that CO2 composed in flue gas altered the HPAM configuration by the decrease of hydrodynamic radius (Rh) and polymer viscosity. Moreover, CO2 delayed the chromium acetate cyclic trimer dissociating into linear trimer and retarded the cross-linking process, which weakened the gelation performance and gel strength. The O2 composed in flue gas led to polymer degradation and seriously impaired the gel long-term stability. Fourier transform infrared spectroscopy (FTIR) analysis revealed that the breakage of Cr-O bond and the disruption of gel network structure were induced by the comprehensive effect of O2 and CO2. [ABSTRACT FROM AUTHOR]

Technological Applications of the Ionizing Radiations of Polymers The study of polymers under ionizing radiations at CIMAP and SECR is aimed first for basic science and second for the management of nuclear waste. Since their industrial development in the 20th century, the use of polymers in various fields is widespread and the electronuclear industry is no exception. Polymers under Ionizing Radiations Radiation-Matter Interaction: Primary Species The difference in behavior between organic polymers and, say, metallic or iono-covalent materials stems from their covalent structure. Under inert environment or under vacuum, macromolecular defects common to all radiation types created in the polymer chains can be: The creation of new groups in the polymer chain. [Extracted from the article]

According to the study of Fonseca et al. ([9]), the nanofibrillated cellulose suspension obtained by mechanical fibrillation can show some characteristics such as individualized micro/nanofibrils, fibers under incomplete fibrillation, clusters and bundles micro/nanofibrils, and non-fibrillated fibers. Chemical treatments and mechanical fibrillation of OCC fibers Morphology Light microscopic images were realized to study the shape of fibers and microfibers after alkaline pulping, bleaching, and fibrillation treatments. Keywords: Microfibrillated cellulose; cellulosic nanofiber; Old Corrugated Container (OCC); recycled fiber; mechanical fibrillation; ; ; ; ; EN Microfibrillated cellulose cellulosic nanofiber Old Corrugated Container (OCC) recycled fiber mechanical fibrillation ZH 9296 9308 13 11/21/22 20221220 NES 221220 Introduction Recently, recycled lignocellulosic materials as an alternative source of fibers have drawn more attention due to the strong environmental impact of high deforestation and the increased demand for fibrous materials (Motaung and Linganiso [22]). [Extracted from the article]

The steam channeling channel formed during steam huff and puff can be blocked by temperature-resistant gel to improve the steam stimulation effect. In this study, a terpolymer prepared by the polymerization of acrylamide, N-Vinyl-pyrrolidone, and 2-acrylamide-2-methypropanesulfonic acid was selected as gelatinizer, hydroquinone, and hexamethylene tetramine were used as cross-linking agents to prepare gel. The stabilization time of the gel at 175 °C was dramatically extended from 3 days to more than 50 days by adding nanoparticles. The gel prepared with 0.6 wt% polymer, 0.1 wt% hydroquinone, 0.1 wt% hexamethylene tetramine, and 0.9 wt% silica nanoparticles can exist stably for 70 days at 175 °C, which provided a potential choice for plugging the steam channeling channel. The rheological experiments showed that the addition of nanoparticles increased the elastic tendency of the polymer solution to improve the structural strength of the heterogeneous network chain. Dynamic light scattering experiments showed that nanoparticles contribute to the dispersion of polymers in water. The micrographs of the gel were observed by scanning electron microscope, verified that the addition of silica nanoparticles strengthened the gel grid structure and increased the gel grid density, which might be one of the main factors to improve the thermal stability of gels. [ABSTRACT FROM AUTHOR]

Niosomes are multilamellar vesicles that efficiently deliver active substance into skin systemic circulation or skin layers. They are used in topical drug delivery system to enhance the skin permeation of active substance. So, the prime objective of this study was to develop a niosomal gel of fusidic acid to increase its skin permeation. Different formulations of niosomes of fusidic acid were designed by varying the cholesterol to surfactant ratio. Formulations containing fusidic acid, cholesterol, dihexadecyl pyridinium chloride, Span 60, or Tween 60 were prepared by thin film hydration method in rotary evaporator. The thin film formed in rotary flask was hydrated by phosphate buffer saline of pH 7.2. The niosomes formed were characterized through entrapment efficiency, size, polydispersity index (PDI), and zeta potential. The S3 formulation containing span 60 showed the highest entrapment efficiency (EE) of niosomes, so it was incorporated into Carbopol gel. Determination of pH, spreadability, rheological, and ex vivo permeation studies was conducted of niosomal gel. The results of ex vivo permeation studies showed high permeation of fusidic acid when gel was applied to an albino rat skin. According to the results and previous studies of niosomes, it can be concluded that niosomes enhanced the permeation of fusidic acid through the skin. [ABSTRACT FROM AUTHOR]

Lactobacillus rhamnosus SD11 is a probiotic derived from the human oral cavity and has potential being used for dental prophylaxis. The cell free supernatant (CFS) of L. rhamnosus SD11 has good antimicrobial and antioxidant effects. This study aimed to incorporate CFS of the probiotic into thermoresponsive copolymers to create a sol–gel formulation. The sol–gel formulation was developed using Poloxamer 407 as the main polymer, which was mixed with natural polymers such as gellan gum, sodium alginate, and xyloglucan in different proportions. The sol–gel formulations were characterized based on their physicochemical parameters such as appearance, pH, viscosity, flow-ability in low temperature, antioxidant and antibacterial activity. An in vitro release study was performed using Franz's diffusion cell and the stability was determined under freeze-thaw cycle conditions. The combination of 15% w/v of poloxamer 407 with 0.5% w/v of sodium alginate was the best sol–gel formulation to deliver the CFS of the probiotic. This study was successful in creating a sol–gel formulation using a thermoresponsive copolymer, that could efficiently deliver CFS of the probiotic L. rhamnosus SD11. [ABSTRACT FROM AUTHOR]

This work presents a facile strategy for the generation of Fe3O4@poly(4-vinylpyridine)-block-polystyrene (Fe3O4@P4VP-b-PS) magnetic polymer nanocomposites. P4VP-b-PS nanoparticles prepared by dispersion RAFT polymerization of styrene in methanol/water in the presence of macro-P4VP chain transfer agent was employed as templates to grow Fe3O4 on polymeric network templates. With the following addition of FeCl3 into the above polymer colloids, pyridyl moieties in P4VP block of nanoparticles could further react with Fe3+ through a coordination reaction to generate Fe3+@P4VP-b-PS nanoparticles. After the subsequent addition of FeCl2 and NH3⋅H2O, the co-precipitation reaction occurred on the surface of the polymeric nanoparticle to form Fe3O4@P4VP-b-PS magnetic polymer nanocomposites. Herein, FT-IR, XRD, TGA, XPS, TEM and VSM were applied to characterize the morphology, structure and magnetism performance of the synthesized magnetic polymeric nanocomposites. [ABSTRACT FROM AUTHOR]

The repeating cycle of freezing and thawing brings about a physical gelation for the solutions of polyacrylonitrile (PAN) in N, N-dimethylacetamide (DMA) for appropriate concentrations. It was revealed from wide-angle-X-ray diffraction that the PAN molecules were cross-linked by the crystallization to form a network through the freezing and thawing steps. The profiles of small-angle-X-ray scattering for the gels showed the excess scattering from the network structure formed through gelation, which could not be observed for the pure PAN solution. A reversible swelling and shrinking were observable for the PAN gel as a function of the relative content of DMA and benzene by varying the mixing ratio. The degree of swelling measured by weight, for the swollen and shrunk gels, was in a range from 0.7 to 8. A scaling relation appeared for the gel swelling between the PAN volume fraction (ϕ) and the shear moduli (G) which was measured by tensile and indentation tests, as G = Gs ×(ϕ)s; Gs= 1200 kPa and s = 2.26 ± 0.23. A discussion is given on the value of the scaling exponent, s, on the basis of the conformation of flexible chain molecules in solution and the analogy in the microscopic and macroscopic properties between semidilute polymer solutions and gels. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (GNPs) are noble metal nanocarriers that have been recently researched upon for pharmaceutical applications, imaging, and diagnosis. These metallic nanocarriers are easy to synthesize using chemical reduction techniques as their surface can be easily modified. Also, the properties of GNP are significantly affected by its size and shape which mandates its stabilization using suitable techniques of surface modification. Over the past decade, research has focused on surface modification of GNP and its stabilization using polymers, polysaccharides, proteins, dendrimers, and phase-stabilizers like gel phase or ionic liquid phase. The use of GNP for pharmaceutical applications requires its surface modification using biocompatible and inert surface modifiers. The stabilizers used, interact with the surface of GNP to provide either electrostatic stabilization or steric stabilization. This review extensively discusses the surface modification techniques for GNP and the related molecular level interactions involved in the same. The influence of various factors like the concentration of stabilizers used, their characteristics like chain length and thickness, pH of the surrounding media, etc., on the surface of GNP resulting in stability have been discussed in detail. Further, this review highlights the recent applications of surface-modified GNP in the management of tumor microenvironment and cancer therapy. [ABSTRACT FROM AUTHOR]

The spontaneous combustion of coal is one of the main disasters affecting safe production. In order to prevent and extinguish mine fires more efficiently, a new type of fire-suppression polymer gel with strong stability has been developed. The optimal formula was determined by testing the gelation time of different ratios of gel components. The measurement of water retention rate, viscosity and permeability of the gel were also carried out to verify the thermal stability and flowability. The effect of gel on the suppression of CO emission during coal oxidation was tested by the temperature-programming experiments. By the thermogravimetric experiments, the influence of gel on coal activation energy was calculated based on the ignition activation energy theory. FTIR was also introduced to analyze the effect of gel on active groups of coal during coal oxidation. Furthermore, the extinguishing mechanism of the gel was analyzed from forming characteristics. It is proven that the strong stable gel is an excellent fire extinguishing material with the advantages of controllable glue time, good water retention and the obvious effects of sealing. [ABSTRACT FROM AUTHOR]

Sulfur is usually contained in existing gel breaker systems for fracturing fluids, which leads to the generation of hydrogen sulfide gas. In the process of fracturing development. The presence of hydrogen sulfide gas would cause equipment corrosion and environmental pollution. In this paper, a system of sulfur-free gel breaker agents for association fracturing fluid was constructed by evaluating the gel-forming and breaking properties of the fracturing fluid applied with this formula. The results showed that the combinations of 0.02% chlorine dioxide and 0.12% to 0.2% citric acid were chosen as the sulfur-free gel breaker formulas at 80 to 100°C. The polymer molecular chains were broken by synergistic effects of low concentration chlorine dioxide and citric acid to reduce the viscosity of association fracturing fluid, achieving gel-breaking. Simultaneously, the influence of hydrogen sulfide on the development process could be inhibited through bactericidal and oxidation actions of chlorine dioxide. The viscosity of the sulfur-free fracturing fluid remains above 50 mPa·s within 60 minutes, the value of the flow regime index was between 0.2593 and 0.3125, and the settling rate in this system was 0.024 to 0.042 mm/s. The temperature resistance, shear resistance, rheological properties, and sand carrying capacity of the sulfur-free fracturing fluid were not inferior to that of the conventional fracturing fluids, which guaranteed the effect of fracturing reformation. This study is of great significance to not only the development of environmental-friendly fracturing fluid but also the prevention and control of toxic and harmful gases, promoting sustainable development of oilfields. [ABSTRACT FROM AUTHOR]

In this paper, an elasto-hydrodynamic constitutive law of the synthetic polymer SEBS gel (styrene-ethylene-butylene-styrene) based on the mechanical characterization extracted from the literature was developed implemented in a numerical code, and the effect of the strain rate was investigated. The proposed law was then implemented in an explicit non-linear FEM software to reproduce various loading configurations in order to validate the accuracy of the model. A good agreement exists between the numerical results of the laws and experimental data in the literature. Numerical analysis reveals that the strain-rate-dependence effect is significant in SEBS gel especially for high strain rates. The present study can therefore be used to predict the mechanical behavior of human surrogate materials and guide the design of protective devices such as body armor. [ABSTRACT FROM AUTHOR]

To overcome the poor water solubility of total flavones of Arisaematis rhizoma, microemulsions (MEs) can be used as a carrier for transdermal administration to promote their solubilization and skin permeability. Here, we investigated the physical compatibility of MEs in hydrogels and their skin permeationenhancing effects. Transparency of microemulsion-based hydrogels (MBGs) was analyzed to evaluate ME compatibility with different hydrogel matrices. Transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy were used to explore the microstructures of MBGs and ME-hydrogel combinations. Uniform and transparent MBG was obtained by adding 1% sodium hyaluronate (SH) to the optimized ME. MBG prepared with SH as a matrix expressed pseudoplastic-fluid and shear-thinning characteristics, making it easy to apply in clinical settings. No new FTIR peak occurred in the MBG compared with ME and hydrogel matrix, indicating a physical combination of ME and the polymer network gel. Nanoscale droplets of ME migrated in the gel network, and the migration capacity and in vitro transdermal permeation flux negatively correlated with SH concentration in the gel system. In conclusion, in MBGs, ME can keep nanoscale droplets migrating in the hydrogel network, thereby enhancing transdermal drug delivery. [ABSTRACT FROM AUTHOR]

The objective of this work is to develop extended release subcutaneous thermo-responsive in situ gel-forming delivery systems using the following commercially available triblock polymers: poly (lactic-co-glycolic acid)-poly (ethylene glycol)-poly (lactic-co-glycolic acid) (PLGA-PEG-PLGA, copolymer A & B) and poly (lactide-co-caprolactone)-poly (ethylene glycol)-poly (lactide-co-caprolactone) (PLCL-PEG-PLCL, copolymer C). Performance of two optimized formulations containing ketoprofen as a model compound, was assessed by comparing in vitro drug release profiles with in vivo performance following subcutaneous administration in rats. This work employs a Design of Experiment (DoE) approach to explore first, the relationship between copolymer composition, concentration, and gelation temperature (GT), and second, to identify the optimal copolymer composition and drug loading in the thermo-responsive formulation. Furthermore, this work discusses the disconnect observed between in vitro drug release and in vivo pharmacokinetic (PK) profiles. In vitro, both formulations showed extended-release profiles for 5–9 days, while PK parameters and plasma profiles were similar in vivo without extended release observed. In conclusion, a clear disconnection is observed between in vitro ketoprofen drug release and in vivo performance from the two thermogel formulations tested. This finding highlights a remaining challenge for thermogel formulation development, that is, being able to accurately predict in vivo behavior from in vitro results. [ABSTRACT FROM AUTHOR]

Recently, solid polymer electrolytes (SPEs) are of great current interest as substitutes to conventional liquid type electrolytes. Although the SPEs significantly alleviate the safety issues of the lithium-ion batteries based on conventional liquid electrolytes, they intrinsically exhibit low ion conductivity. In this study, a bicontinuous solid polymer electrolyte containing polyacrylonitrile (PAN) membrane and a mixture of succinonitrile (SN) and lithium bis(trifluoromethanesulfonyl)imide was prepared with different molarities of the lithium salt. Porous PAN membrane was fabricated via a thermally induced phase separation method (TIPS). The PAN-based SPE exhibited the maximum ionic conductivity of ∼5.0 × 10−3 S/cm at the salt molarity of 1.0 M. [ABSTRACT FROM AUTHOR]

Polymer gel served as a temporary plugging agent for fluid loss control during well completion and workover has received great attention in recent years. Gel breaking as well as flowback is the most concern after the downhole operations such as perforation, replace tubing. Using oxidative breaker as chemical method or jetting nozzle as mechanical strategy were mainly employed to remove gel. The former often fails to fully contact with the gel, and the gel breaking efficiency is not ideal. The latter, although effective, greatly increases the cost of operation. Thermal degradation of gel plug at reservoir temperature after the operation is more welcome. In this paper, we combined aging experiments, Fourier Transform Infrared Spectroscopy (FTIR) analysis, Scanning Electronic Microscopic (SEM) and Differential Scanning Calorimetry (DSC) experiment to reveal the degradation mechanism of seawater based temporary plugging gel crosslinked by polyethyleneimine (Abbreviated as "gel plug"). In addition, the fluid loss control ability and formation damage characteristic of the gel plug were evaluated through core flooding experiment. The dynamic process of gel degradation was studied by DSC technology, and the thermodynamic parameters were respectively calculated by Kissinger, Flynn-Wall-Ozawa, Horowitz-Metzger and Coats-Redfern model. According to the desired activation energy, Semenov equation and relevant data were used to derive the model for predicting gel degradation time. The developed model conforms to the aging experimental results with correlation coefficient of 0.988. This study provides knowledge for the optimization of temporary plugging gel technology in high-temperature gas wells. [ABSTRACT FROM AUTHOR]

Sodium alginate/poly(vinyl alcohol) hydrogels containing Echinacea purpurea extract (0–20%) with antioxidant activity (73.2 ± 2.4% inhibition, 2.54 ± 0.096 TEAC) were developed using UV radiation. The swelling ability increases with increased extract contents and it reaches about 300%, which is related to the porosity. The presence of 20% of extract directly impacted the morphology, which became more porous. The degradation tests indicate no significant differences in pH and conductivity. However, the gradual increase of conductivity exhibits the expected rate of material degradation over time. In the case of hydrogels containing 5% and 15% of extract, the analyzed echinacoside was being released during 6 days. [ABSTRACT FROM AUTHOR]

To research the action mechanism of silica nanoparticles in polymer gel, a novel silica nanoparticle strengthened polymer gel (SNSPG) with partially hydrolyzed polyacrylamide (HPAM) and organic zirconium is studied. After adding nanoparticles, when the concentration of HPAM is low (˂0.8 wt%), viscoelasticity of this system has few increases compared with before. The nanoparticles are not strong to bridge the loose three-dimensional network structure. Furthermore, Dynamic Light Scattering (DLS) and zeta potential measurements were tested to explain enhancement of high concentration system (0.8 wt%) by nanoparticles. Differential Scanning Calorimeter (DSC) and Environmental Scanning Electron Microscope (ESEM) measurements results together support the action mechanism of this research. In high polymer concentration, proper amounts of nanoparticles participated in the gelation process to make polymer gel tighter, while too many nanoparticles blocked cross-linking of polymer and cross linker to weaken the system enhancement. This research develops a strengthened polymer gel system which has broad application prospects, and the action mechanism this research proposed provides theoretical support for industrial production. [ABSTRACT FROM AUTHOR]

This review article covers recent developments in thiol-X polymerizations as applied to the production of polymer colloidal particles. These polymerizations include thiol-ene, thiol-yne, thio-Michael, and thio-isocyanate polymerizations. Such thiol-X chemistries are facile reactions that offer high yields, rapid synthesis using mild conditions, orthogonality with other methods of organic synthesis, compatibility with a variety of monomer species, and can be radical or base mediated. Recent years have seen the employment of these reactions for the synthesis of polymer colloids in heterogeneous polymerizations such as suspension, dispersion, emulsion, and miniemulsion polymerizations, using microfluidic and batch production methods. A particular feature of thiol-X chemistries is their step-growth mechanism for molecular weight development, which contrasts with chain-growth polymerizations that are more commonly used in heterogeneous polymerizations. This aspect of thiol-X polymerizations allows for straightforward polymer functionalization simply through controlling the functional group stoichiometry. Another benefit is that radical-mediated thiol-X chemistries can be conducted with photo, thermal, or redox initiation, which epitomizes the practicality/adaptability of these reactions. Examples of highly functionalized thiol-X colloidal polymers are provided along with how such functionalization can be leveraged in order to provide desired properties. Therefore, polymer colloids made by thiol-X chemistries are expected to be a platform upon which many new technologies can be built. [ABSTRACT FROM AUTHOR]

Introduction: Despite the advent of immunotherapy as a promising therapeutic, glioblastoma (GBM) remains resistant to using checkpoint blockade due to its highly immunosuppressive tumor milieu. Moreover, current anti-PD-1 treatment requires multiple infusions with adverse systemic effects. Therefore, we used a PCL:PEG:PCL polymer gel loaded with anti-PD-1 and implanted at the site of lymph nodes in an attempt to maximize targeting of inactivated T cells as well as mitigate unnecessary systemic exposure. Methods: Mice orthotopically implanted with GL261 glioma cells were injected with hydrogels loaded with anti-PD-1 in one of the following locations: cervical lymph nodes, inguinal lymph nodes, and the tumor site. Mice treated systemically with anti-PD-1 were used as comparative controls. Kaplan-Meier curves were generated for all arms, with ex vivo flow cytometric staining for L/D, CD45, CD3, CD4, CD8, TNF-α and IFN-γ and co-culture ELISpots were done for immune cell activation assays. Results: Mice implanted with PCL:PEG:PCL hydrogels carrying anti-PD-1 at the site of their lymph nodes showed significantly improved survival outcomes compared to mice systemically treated with anti-PD-1 (P = .0185). Flow cytometric analysis of brain tissue and co-culture of lymph node T cells from mice implanted with gels demonstrated increased levels of IFN-γ and TNF-α compared to mice treated with systemic anti-PD-1, indicating greater reversal of immunosuppression compared to systemic treatment. Conclusions: Our data demonstrate proof of principle for using localized therapy that targets lymph nodes for GBM. We propose an alternative treatment paradigm for developing new sustained local treatments with immunotherapy that are able to eliminate the need for multiple systemic infusions and their off-target effects. [ABSTRACT FROM AUTHOR]

The unique properties of gels, particularly polymer based gels have drawn attention of the researchers since ages. This review highlights the fundamental aspects of polymeric gels, enumerating them in terms of differences in synthesis or crosslinking mechanism. To broaden the possibility of these polymeric gels to decontaminate textile effluents comprising of toxic dyes, the scope of commonly used dye removal methodologies are duly discussed herein. Adsorption is recognized as the most reliable, commercially viable and eco-friendly technique for dye removal. In this context, thoughtful selection of gel components is crucial to fine tune the flexibility, robustness, selectivity of the adsorbents to accomplish maximum removal efficiency, ability to regenerate, etc. Therefore, in this review, we have summarized the recently developed polymeric gel based adsorbents for efficient removal of detrimental dyes from wastewater. [ABSTRACT FROM AUTHOR]

In order to explore the influence of water dilution on performance of Cr3+ polymer weak gel in porous medium, the performances of pure polymer solution and Cr3+ polymer weak gel were studied according to the laboratory testing of viscosity, micro-structure performances (polymer molecule aggregate dimension, polymer molecule aggregate configuration and Zeta potential), seepage characteristics and oil displacement effect under the condition of water dilution. The results indicated that, after diluting by water, pure polymer solution and Cr3+ polymer weak gel had an almost same viscosity, but there were obvious differences in micro-structure performance and seepage characteristics. Different with pure polymer solution, with the decrease of polymer concentration, on the one hand, the influence of free Cr3+ on electric double layer and shielding effect on electrostatic exclusion got weaker, on the other hand, water molecules were attracted by hydrophilic groups on the Cr3+ polymer weak gel molecular chains and then entered into the three-dimensional spatial structure of Cr3+ polymer weak gel, producing hydration and expansion. Therefore, the polymer molecule aggregate dimension of Cr3+ polymer weak gel presented a trend of continuous increasing. This characteristic was good for keeping the injection pressure at a higher value during diluting in the porous medium, which could be used to improve oil recovery in offshore oilfield through conducting injection of water-alternating- Cr3+ polymer weak gel. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) gels belong to a group of smart materials whose attributes can be altered when it is exposed to an external magnetic field. In this paper, the investigation on the creep behavior of MR gels under constant stress is performed. MR gels are prepared by dispersing carbonyl iron (CI) microparticles of different volume percentages (10%, 20%, 30%) in a polymer gel. Using a free decay test apparatus built in-house, the effect of the magnetic field on the creep behavior of MR gels with various volume percentages of CI particles is studied, and the results are compared. From the results, a clear increasing trend is noticed in the creep resistance of the magnetic gel with the increase in the volume percentage of the particles under the same magnitudes of the magnetic field. The obtained experimental creep data are fitted suitably using a three-parameter model. [ABSTRACT FROM AUTHOR]

In this study, malachite green-imprinted sol-gel polymer (MG-imp) has been anchored on the surface of mercaptopropyltrimethoxysilane-capped Mn-doped ZnS quantum dots (MPTMS-Mn:ZnS) and characterised by Fourier Transform-Infrared Spectroscopy and Scanning Electron Microscopy. Surface imprinting property of MPTMS-Mn:ZnS (QDs) covered by MG-imprinted sol-gel (MG-imp-QDs) was elucidated by differential pulse voltammetry and room temperature phosphorescence (RTP) measurements. Selective determination of MG in the presence of analogue molecules was managed upon optimised solution parameters based on the RPT quenching efficiency of MG-imp-QDs nanoparticles. Electrochemical measurement was also carried out by fabricating electrode modified with MG-imp-QDs nanoparticles in order to confirm the existence of imprinting effect and spectral overlap causing to inner filter effect during the RTP measurements. The linear concentration range and limit of detection for determining of MG in buffer solution were found to be 0.03–1.84 µM and 3.2 nM, respectively. [ABSTRACT FROM AUTHOR]

Systems composed of soft matter (e.g. liquids, polymers, foams, gels, colloids, and most biological materials) are ubiquitous in science and engineering, but molecular simulations of such systems pose particular computational challenges, requiring time and/or ensemble-averaged data to be collected over long simulation trajectories for property evaluation. Performing a molecular simulation of a soft matter system involves multiple steps, which have traditionally been performed by researchers in a 'bespoke' fashion, resulting in many published soft matter simulations not being reproducible based on the information provided in the publications. To address the issue of reproducibility and to provide tools for computational screening, we have been developing the open-source Molecular Simulation and Design Framework (MoSDeF) software suite. In this paper, we propose a set of principles to create Transparent, Reproducible, Usable by others, and Extensible (TRUE) molecular simulations. MoSDeF facilitates the publication and dissemination of TRUE simulations by automating many of the critical steps in molecular simulation, thus enhancing their reproducibilitya. We provide several examples of TRUE molecular simulations: All of the steps involved in creating, running and extracting properties from the simulations are distributed on open-source platforms (within MoSDeF and on GitHub), thus meeting the definition of TRUE simulations. [ABSTRACT FROM AUTHOR]

Since 2015, the Laboratoire Léon Brillouin (LLB), operated by the CEA and the CNRS in France, has been developing a project plan to build a facility using a compact accelerator driven neutron source. In collaboration with accelerator and neutron experts from the CEA, a reference design for a source dubbed SONATE (Source cOmpacte de Neutrons s'Appuyant sur la Technologie des accélératEurs) emerged and the first proofs of concept have been established on the IPHI-Neutron platform [[1]]. We are considering the different degrees of freedom in the design of a Compact Accelerator-based Neutron Source (CANS) and deriving machine parameters suitable for a CANS dedicated to neutron scattering, which would provide sufficient performance to be operated as a neutron scattering facility. For proton energies in the range 3 MeV-60 MeV, beryllium and lithium are roughly equivalent in terms of neutron yield. [Extracted from the article]

Ce-substituted strontium hexagonal M-type SrCexFe12-xO19 ferrites (x = 0.0, 0.03, 0.05, 0.07, and 0.1) and various concentrations of poly(N-vinilpyrrolidone) (PVP) polymer were prepared by citrate sol-gel auto-combustion route, and their structural and magnetic properties were studied. The Fourier transform infrared spectroscopy (FT-IR) revealed bands at 437, 549, and 598 cm−1, related to the stretching vibrating bonds of Fe-O. The X-ray diffraction analysis (XRD) showed that in all samples, the SrFe12O9 phase is completely formed, and the peaks are taken with the standard card (JCPDS 01-084-1531) correspond to the type of strontium hexaferrite with the P63/mmc space group. Field emission scanning electron microscopy (FESEM) analysis revealed the hexagonal like the shape of all samples. Vibrating sample magnetometer (VSM) results showed ferromagnetic nature for all the specimens. By increasing the dopants content, coercivity (Hc) and saturation magnetization (Ms) erratically changed but Hc decreased with increasing PVP amount. The complex permittivity, complex permeability and microwave absorption properties of the resulting powder were measured in the range of 8–13 GHz. [ABSTRACT FROM AUTHOR]

Cross-linked polymer (CLP) composed of poly(ethylene glycol) methyl ether acrylate and poly(ethylene glycol) diacrylate has been used in synthesizing gel electrolyte. A set of electrolyte samples was synthesized using gel casting method by varying the weight percentage ratio of cross-linked polymers from 2–14 % in an incremental order (2 %) with respect to poly (ethylene oxide) (PEO) and evaluated its performance by employing in the fabrication of dye-sensitized solar cells. The synthesized polymer was subjected to different analytical techniques such as NMR, TGA, DSC, GPC, and FTIR to confirm the materials. The molecular weight of the CLP has been measured using GPC and the obtained value is found to be 3.655 KDa with polydispersity of 1.94. The CLP-PEO gel electrolyte with 10 % weight ratio has obtained the highest ionic conductivity of 3.07 × 10−6 S/cm−1 at room temperature and best photo-conversion efficiency of 5.1 % was achieved for the same. [ABSTRACT FROM AUTHOR]

For the application of polymer gels, it is necessary to control independently and precisely their various physical properties. However, the heterogeneity of polymer gels hinders the precise control over the structure, as well as the verification of theories. To understand the structure-property relationship of polymer gels, many researchers have tried to develop a homogeneous model network. Most of the model networks were made from polymer melts that did not have a solvent and had many entanglements in the structure. Because the contribution of entanglements is much larger than that of chemical crosslinking, it was difficult to focus on the crosslinking structure, which is the structure considered in conventional theories. To overcome such a situation, we have developed a new model network system that contains much solvent. Specifically, we fabricated the polymer gel (Tetra-PEG gel) by mixing two types of solutions of tetra-armed poly(ethylene glycol) (Tetra-PEG) with mutually reactive end groups (amine (-PA) and activated ester (-HS)). Because the existence of a solvent strongly reduces the effect of entanglements, the effect of the crosslinking structure on the physical properties can be extracted. In this review, we present the structure-property relationship of Tetra-PEG gel. First, we show the structural homogeneity of Tetra-PEG gels. Then, we explain gelation reaction, elastic modulus, fracture energy and kinetics of swelling and shrinking of Tetra-PEG gels by comparing the theories and experimental results. [ABSTRACT FROM AUTHOR]

In this research work, manganese ferrite nanoparticles (MnFe2O4) were synthesized by three different methods including the co-precipitation, sol-gel, and hydrothermal route. Structure, size, morphology, and magnetic properties of nanostructures were determined and compared using X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy analysis (FESEM), and the vibration sample magnetometer (VSM). X-ray diffraction analysis from Debye–Scherrer's formula with the (2θ = 35.08°) peak indicated that the mean size of the synthesized manganese ferrite nanocrystallites were obtained to be 36, 45, and 16 nm for co-precipitation, sol-gel, and hydrothermal, respectively. Also, the sample prepared by the hydrothermal method has the lowest crystal sizes, which it is approved by FESEM analysis. Field emission scanning electron microscopy analysis images confirmed the existence of three types of basic morphology of MnFe2O4 nanoparticles: spherical shape, multi-walled hollow nanosheets, and reticular structure. In addition, Based on VSM data magnetization saturation (Ms) was 41.89 emu/g for hydrothermal synthesized samples, 38.76 emu/g for co-precipitation samples, and 9.52 emu/g for sol-gel samples. These findings show that various methods of nanoparticle synthesis can lead to different particle sizes and magnetic properties. [ABSTRACT FROM AUTHOR]

A new polymer gel nanocomposite is fabricated for excess water production control (water shut off) in petroleum reservoirs and its rheological behavior is evaluated in the presence of sea water and formation water at the temperature of 100 °C. It is shown that at a high salinity without using SiO2 nanoparticles, the elastic modulus of synthesized polymer gel in the presence of sea water and formation water are 12.5 Pa and 9.8 Pa respectively. However by incorporation of SiO2 nanoparticles in the polymer gel matrix, the elastic modulus of synthesized polymer gel in the presence of sea water and formation water can be improved to 13.56 Pa and 11.57 Pa respectively, which is quite interesting from reservoir engineering viewpoint. Equilibrium Swelling Ratio (ESR) of the nanocomposite polymer gel in sea water and formation water decreases as the concentration of the SiO2 increases. Thermal stability of the polymer gel is investigated by differential scanning calorimetry (DSC) measurements. The inflexion temperature of the polymer gel is improved by incorporation of 2000 ppm SiO2 nanoparticles. The fabricated polymer gel nanocomposite in this work can have potential application in reduction of excess water production during enhanced oil recovery (EOR) operations in petroleum industry. [ABSTRACT FROM AUTHOR]

A novel flexible free-standing films of polyvinyl alcohol (PVA)/silica polymer network dispersed cholesteric liquid crystals (CLC) have been prepared by the sol-gel process. In the hydrolysis of silicon alkoxides tetraethoxysilane (TEOS) processes, the silica having -OH with the -OH groups on PVA formed polymer networks with Si-O-C bonds by dehydration. The cholesteric liquid crystals were incorporated into the networks. The free-standing films were obtained by the spin-coating method. In order to improve the compatibility and microstructure of the cholesteric liquid crystals with PVA/silica polymer networks, the amphiphilic compound of hexadecyl trimethyl ammonium bromide (HDTMA) was introduced into the forming film solutions. Effects of the different ratios of raw materials on the structure of films were investigated. The microscopic morphology of free-standing films and the uniform dispersion of CLCs in the films have been characterized by polarizing optical microscopy (POM), the field emission scanning electron microscope (FESEM), Fourier transform infrared (FT-IR) spectrometer and atomic force microscope (AFM). The free-standing films exhibiting excellent CLC droplets dispersion, mechanical stability, and good flexibility could be useful for flexible displays, switchable optical elements and smart windows. [ABSTRACT FROM AUTHOR]