Surface-active Polymers Research Articles

Nanosuspension Technology for Delivery of Poorly Soluble Drugs and Its Applications: A Review

Now a days, many drug candidates are water insoluble hence they show a limited drug release and poor bioavailability. It is difficult to formulate these drugs by conventional dosage form. Nanosuspension technology is a promising approach to solve the problems of poorly soluble and less bioavailable drugs. Nanosuspension is a very finely colloidal, biphasic, and uniformly dispersed solid drug particles in a suitable aqueous vehicle, having a particle size below 1 μm stabilized by suitable surface active agents and polymers. Nanosuspensions are prepared by various suitable techniques for drug delivery applications. Due to reduced particle size at the nano scale, surface area, saturation solubility, dissolution velocity and bioavailability of BCS class II and class IV drugs are increased sufficiently. Nanosuspension is suitable to administration via various routes such as oral, intravenous, topical, pulmonary and ocular delivery systems. Nanosuspension can be also used for targeting purpose in various diseases such as cancer, HIV and production of sustained and extended release products by choosing suitable polymers. Production and manufacturing are not complicated, easy to scale up. Top down and bottom technologies are used for the preparation of nanosuspensions. It includes methods such as high-pressure homogenization, by milling media method, precipitation method, probe sonication, dry-co-grinding, supercritical fluid method, and lipid emulsion method. Formulation consists of stabilizers, surfactant, and solvents. Nanosuspension can be stored in the form of dry powder using spray drying, freeze drying techniques. This review describes the advantages, various methods of preparation, formulation consideration and characterization of nanosuspension.

Optimization of W5 fault block surface-active polymer flooding scheme

According to the current situation of the W5 fault block, it is necessary to carry out the surface-active polymer flooding. By physical simulation, the optimal concentration is 1000 mg/L, the optimal slug size is 0.3PV, and the earlier the injection opportunity, the slower the injection rate, the higher the recovery rate. By numerical simulation, the recovery rate of the optimal scheme is 27.2%. Compared with the water flooding, the cumulative oil increase is 3.33 × 104 t, the enhanced oil recovery is 5.74%, the oil-enhancing amount of one ton surface-active polymers is 307.73 t/t, and the ratio of output to input is 16.30.

Experimental study on surface-active polymer flooding for enhanced oil recovery: A case study of Daqing placanticline oilfield, NE China

Abstract Experiments on surface-active polymer flooding for enhanced oil recovery were carried out by detection analysis and modern physical simulation technique based on reservoirs and fluids in Daqing placanticline oilfield. The experimental results show that the surface-active polymer is different from other common polymers and polymer-surfactant systems in molecular aggregation, viscosity and flow capacity, and it has larger molecular coil size, higher viscosity and viscosifying capacity, and poorer mobility. The surface-active polymer solution has good performance of viscosity-increasing and viscosity retention, and has good performance of viscoelasticity and deformability to exert positive effects of viscosifying and viscoelastic properties. Surface-active polymer can change the chemical property of interface and reduce interfacial tension, making the reservoir rock turn water-wet, also it can emulsify the oil into relatively stable oil-in-water emulsion, and emulsification capacity is an important property to enhance oil washing efficiency under non-ultralow interfacial tension. The surface-active polymer flooding enlarges swept volume in two ways: Microscopically, the surface-active polymer has mobility control effect and can enter oil-bearing pores not swept by water to drive residual oil, and its mobility control effect has more contribution than oil washing capacity in enhancing oil recovery. Macroscopically, it has plugging capacity, and can emulsify and plug the dominant channels in layers with high permeability, forcing the injected fluid to enter the layer with medium or low permeability and low flow resistance, and thus enlarging swept volume.

Antimicrobial properties of amylose-fatty ammonium salt inclusion complexes

Amylose-fatty (C12-C16) ammonium salt inclusion complexes are effective antimicrobial polymers causing growth inhibition of microbes at concentrations as low as 40 μg/mL of the complex (2 μg/mL active cationic ligand). The complex was more effective at controlling microbes than the uncomplexed ligand. The complexes were found to be particularly effective at inhibiting the growth of fungi, yeast, gram (+) bacteria, and algae; its performance was affected by pH. The complexes were not hemolytic at concentrations up to 2000 μg/mL. These agents were determined to be surface active polymers and their antimicrobial mode of action may involve cell membrane thinning or disruption, causing moderate leakage. Increased ligand concentration provided increased antimicrobial activity. Solutions of amylose complexes were found to be stable, retaining their antimicrobial efficacy after autoclaving, or after storage at room temperature for 6 months. Antimicrobial amylose complexes were produced using readily available inexpensive materials via an easily scalable process.

Green conventional and first-order derivative fluorimetry methods for determination of trimebutine and its degradation product (eudesmic acid). Emphasis on the solvent and pH effects on their emission spectral properties.

In this report, the fluorescence properties of the antimuscarinic drug trimebutine maleate (TRB) were fully studied and characterized. TRB exhibited intrinsic fluorescence that is greatly dependent on the local environmental factors including the solvent nature and the pH. Yet, its fluorescence was not significantly influenced by the existence of some surface active agents and polymer. The outcomes of this investigation verified that TRB fluorescence emission is intense in ethanol: 1.0 M aqueous acetic acid (9:1, v/v) with emission maxima at 357 nm and excitation maxima at 270 nm. Whereas, going towards higher pH causes fluorescence quenching. These conditions permitted ultrasensitive fluorimetric determination of TRB over the concentration range of 2.00-1500.0 ng/mL with a lower detection limit of 0.40ng/mL Application for the determination of TRB in tablets, ampoule and suspension was successfully achieved with %recoveries ranged between 98.21-100.17%. Furthermore, a first order derivative fluorimetric method was validated for resolving and simultaneous determination of TRB and its degradation product and impurity, eudesmic acid (EUA) making use of the pH-mediated fluorescence spectral shift of EUA. An ethanolic solution containing acetate buffer (pH 5.3) was used for this goal with excitation at 255 nm and measurement of the first order derivative peak amplitudes at respective zero-crossing points of 375 and 351 nm over the corresponding concentration ranges of 20.00-500.00 and 10.00-300.00 ng/mL for TRB and EUA, respectively. The two methods were assessed regarding greenness and eco-friendship by the National Environmental Methods Index and analytical eco-scale score approaches which confirmed their excellent greenness and safety.

Performance of enlarging swept volume by Surface-active Polymer flooding for enhancing oil recovery

ABSTRACTSurface-active Polymer is a novel multifunctional active polymer for chemical flooding in mature oilfield, and the mechanism of enhancing oil recovery by Surface-active Polymer flooding is to be further studied. Performance of enlarging swept volume for enhancing oil recovery by Surface-active Polymer flooding has been evaluated in this paper. The effect and contribution rate of mobility control of Surface-active Polymer flooding for enhancing oil recovery were tested firstly, and then microscopic experiments on enlarging swept volume based on microetching models have been carried out, and macroscopic evaluation of enlarging swept volume based on heterogeneous models with cores grouped in parallel was carried out. Mobility control effect and plugging by emulsifying make Surface-active Polymer have significant performance of enlarging swept volume. Enlarging swept volume both on the macroscopic and the microscopic is the basic principle of Surface-active Polymer flooding for enhancing oil recovery.

Migration of fluorinated alkyd and fluorinated tung oil additives for partially self-stratifying coatings

A high solids alkyd coating was developed with surface active polymers to improve performance at the surface, while maintaining adhesion at the substrate. A fluorinated long oil alkyd (FLOA) was prepared through a partial polyol substitution of 2,2,3,3,4,4,5,5-octafluoro-1,6- hexanediol for glycerol with phthalic anhydride and linseed oil in a long oil alkyd (LOA). A previously synthesized fluorinated tung oil (FTO) reactive diluent was also synthesized via a Diels- Alder reaction with 2,2,2-trifluoroethyl methacrylate. The alkyd and reactive diluent were characterized with 1H-NMR and MALDI-TOF mass spectroscopy. The FLOA was used as an additive up to 40 wt.% of the total alkyd, in increments of 10 wt.%. The FTO was used as an additive up to 10 wt.% of the total alkyd, in increments of 2.5 wt.%. The film formation was examined using scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDX) to show phase separation and domains of the low surface energy additive. Analysis of a cross-section of the coating showed an increase in fluorine concentration of 40% at the surface, compared to substrate, which preserves adhesion. A variety of coatings tests were performed to evaluate hardness, adhesion, mechanical strength and flexibility of the coating. The contact angle of FLOA/FTO coatings shifted from hydrophilic to hydrophobic surface energy. An increase in corrosion protection for FLOA/FTO coatings was evaluated using electrochemical impedance spectroscopy (EIS).

IMPROVEMENT OF OCCUPATIONAL SAFETY AT OIL AND GAS OBJECT TERRITORIES BY INCREASING EFFICIENCY OF WATER FIRE SUPPRESSION SYSTEM

An analysis of working conditions of rescue service and operational personnel during a fire has been conducted, when open fire is one of the dangerous factors, especially at the oil and gas object territories. It is also considered to be quite an important environmental factor, which under certain circumstances leads not only to deterioration of working conditions of operational personnel at a particular facility, but also to severe environmental pollution. This is especially true of firefighters, rescuers and other civil protection workers who are subjected to harmful effects of high temperature, thermal radiation, as well as hazardous combustion products while eliminating emergency situations. Improvement of working conditions during emergency rescue operations can be achieved by reducing their conduct time, as well as by increasing a distance between a rescuer and ignition point. This can be achieved by using fire extinguishing solutions with additives of surface active agents and polymers in fire suppression systems. These substances are introduced into fire hoses and pipelines, which allows to increase the expense of extinguishing solution, flow range from the jet nozzle and reduce duration of fire suppression operation. The laboratory conducted experiments allowed to select a specific polymer - polyethylene oxide, its molecular weight and solution concentration, which provides the maximum possible reduction of hydraulic resistance in a fire hose and a jet nozzle.

Hydroxypropyl cellulose as a green polymer for thermo-responsive aqueous foams.

Hydroxypropyl cellulose (HPC) is a surface active polymer that can change its solubility as a function of temperature. This makes HPC interesting for responsive foams, where macroscopic properties need to be reversibly changed on demand. Analysis of aqueous HPC foams as a function of temperature showed a moderate decrease in foam half-life time from 9000 to 4000 s, when the temperature was increased. However, within a narrow temperature range of ±2 °C a dramatic decrease in half-life time to <120 s was observed at 43 °C in the absence and at 31 °C in the presence of 0.7 M NaCl. These drastic changes are highly reversible and are associated to the lower critical solution temperatures (LCST) of HPC in aqueous solutions. In fact, dynamic light scattering experiments indicate that HPC molecules form aggregates at temperatures >31 °C (0.7 M NaCl) and >43 °C (0 M NaCl), which shrink in size when the temperature is increased further. From these results, we conclude that the LCST of 1 MDa HPC is at 43 °C when no salt is present and is at 31 °C in aqueous solutions with 0.7 M NaCl. In addition, shear rheology of bulk solutions and surface tensiometry indicate that the solution's viscosity and the surface pressure dramatically change at the respective LCSTs. Obviously, the solvent's viscosity triggers substantial changes in foam drainage at the LCST, which is shown to be the main driving force for the temperature responsiveness of HPC foams.

Unravelling the Mechanism of Stabilization and Microstructure of Oil-in-Water Emulsions by Native Cellulose Microfibrils in Primary Plant Cells Dispersions.

It is long known that oil-in-water emulsions can be stable against coalescence in homogenized plant cell wall dispersions because of the presence of surface-active biopolymers. When plant cell wall material is homogenized to the extent of deagglomeration of the cellulose microfibrils (CMFs), a much more complex dispersed system is obtained. Here we show that in such complex systems both surface active soluble polymers and individual CMFs are at the origin of this stabilization against coalescence, as they form a shell around the oil droplets providing Pickering-like stabilization. Individual CMFs and bundles of them in the presence of soluble biopolymers form a hybrid network in the continuous phase linking the droplets, creating a viscoelastic network that prevents the droplets from coalescing. Depletion induced attraction caused by soluble biopolymers and dispersed CMFs induces the formation of oil droplet clusters at low CMF concentrations leading to a highly heterogeneous distribution of oil droplets. This effect diminishes at high CMF concentrations at which the strong viscoelastic network arrests the droplets. These findings are important steps toward controlling complex dispersed systems comprising CMF-polymers mixtures with a second liquid or solid dispersed phase.

Effect of different surface active polysaccharide derivatives on the formation of ethyl cellulose particles by the emulsion-solvent evaporation method

This paper aims at a better understanding of the systematic production of the ethyl cellulose (EC) particles by using an emulsification-solvent evaporation method in the presence of different polysaccharide derivatives. In particular, the role of different surface active polymers i.e. one ionic—carboxymethyl cellulose, one nonionic—hydroxyethyl cellulose, and two amphiphilic—high molecular weight methyl cellulose and low molecular weight methyl cellulose on EC particle formation was investigated. We have established how individual surface active polysaccharides with varying concentration from 0.1 to 3.0 wt% affect particle size and its distribution, particle shape, surface charge, and particle surface morphology. The interdependencies between surfactant nature and concentration at constant processing parameters and the subsequent nano- to micro-particle characteristics are discussed. It was determined that the particle size, surface morphology, supramolecular structure and surface properties of EC particles, prepared by an emulsion evaporation method can be effectively controlled by the type and concentration of used polysaccharide surfactant yielding spherical particles sizes from 170 nm to the micrometer level with smooth particle surfaces or remarkably a wrinkled surface morphology or “particle on particle” structures.Graphical abstract

Anisotropic One-Dimensional Aqueous Polymer Gel Electrolyte for Photoelectrochemical Devices: Improvement in Hydrophobic TiO2–Dye/Electrolyte Interface

Aqueous photoelectrochemical devices have emerged recently as promising area because of their economic and ecological friendliness. In the present work, we have expedited surface active amphiphilic quasi-solid aqueous polymer gel electrolyte (PGE) with hydrophobic sensitizer SK3 in water-based dye sensitized solar cell (DSSC). PGE was prepared from amphiphilic block copolymer (PEO)–(PPO)–(PEO) with iodide–triiodide couple in pure aqueous media without any organic solvent. This block copolymer, with iodide-triiodide salt exhibits 1D-lamellar microcrystalline phase which shows stability in the temperature range of 25–50 °C. Parallel (||al) and perpendicular (⊥ar) alignment of anisotropic lamellar microcrystalline phase pertaining by PGE were characterized and applied in quasi-solid DSSC. Temperature dependency of ionic conductivity, triiodide diffusion, differential scanning calorimetry, viscosity, and 1-D lamellar anisotropic behavior were studied. Surface active effect of PGE at the hydrophobic dye sensit...

Preparation and self-assembly properties of surface active hydrophobically associating polyacrylamide

ABSTRACTA novel surface-active polymer (PCPAM) was synthesized by free-radical polymerization of acrylamide (AM), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and surfmer (ACP) which was previously prepared by reacting Nonaphenol polyethyleneoxy ether-10 (OP-10) and allyl chloride. The structure of PCPAM was characterized by FT-IR, 1H-NMR, GPC and TGA. In addition, the self-assembly properties of the copolymer were studied with viscosimetry and fluorescence probe method. Moreover, the activity of PCPAM solution was examined with surface tension, IFT and emulsifying ability. Results indicated that, the solution viscosity proportionally increased with PCPAM concentrations, leading in the formation of a three-dimensional network with surface activity and thermal stability, and the CAC of PCPAM was about 1.5 g/L, PCPAM can reduce the interfacial tension between crude oil and water, the IFT value was about 0.029 mN/m when the concentration of PCPAM beyond CAC and have good ability to form stable emulsions. Furthermore, the core flooding experimental demonstrated that the oil displacement efficiency of PCPAM increased by about 17.4%, which is better than 13.87% and 15.55% based on HPAM flooding and HPAM/surfactant flooding, respectively. All of these properties indicate that the PCPAM was an excellent chemical for chemical enhanced oil recovery.

Hierarchically structured particles for micro flow catalysis

This work introduces the investigation of three-layered metal/polymer/polymer hierarchically structured composite particles, prepared by a microfluidic synthesis method combined with layer-by-layer (LBL) technology. Composite particles made of multiple length scales ranging from nanometer to sub-micrometer and submilimeter, and their potential application in catalysis is shown. In the first part, with the advantage of microreaction technology, platinum nanoparticles of a precise size were synthesized and electrostatically combined to oppositely charged surface-active polymer nanoparticles. After controlling the nanoparticles ratio and metal density on the polymer surface, nanocomposite particles of high specific surface to volume ratio were immobilized on the surface of microfluidically prepared polyacrylamide hydrogel particles, in second part. Platinum nanoparticles offer the possibility to be used as potential catalysts. For further study, the catalytic activity of the obtained hierarchical metal-polymer composite particles was evaluated by bleaching an azo-dye (Cochenille Red) with sodium borohydride. Different experiments have been conducted in the absence as well as in the presence of the composite particles. It has been found that a significant enhancement of the bleaching rate was realized in case of platinum containing composite particles.

Orientation Control of Block Copolymers Using Surface Active, Phase-Preferential Additives.

Orientation control of thin film nanostructures derived from block copolymers (BCPs) are of great interest for various emerging technologies like separation membranes, nanopatterning, and energy storage. While many BCP compositions have been developed for these applications, perpendicular orientation of these BCP domains is still very challenging to achieve. Herein we report on a new, integration-friendly approach in which small amounts of a phase-preferential, surface active polymer (SAP) was used as an additive to a polycarbonate-containing BCP formulation to obtain perpendicularly oriented domains with 19 nm natural periodicity upon thermal annealing. In this work, the vertically oriented BCP domains were used to demonstrate next generation patterning applications for advanced semiconductor nodes. Furthermore, these domains were used to demonstrate pattern transfer into a hardmask layer via commonly used etch techniques and graphoepitaxy-based directed self-assembly using existing lithographic integration schemes. We believe that this novel formulation-based approach can easily be extended to other applications beyond nanopatterning.

Ultrasonic Treatment Enhanced Surface Modification of Titanium Oxide by Tailor-Made Surface-Active Polymers

The surface modification of titanium dioxide in aqueous dispersions of specially tailor-made periodic acrylic acid/isobutylene copolymers, poly(acrylic acid)/polystyrene graft copolymers, and hydrophobically modified polyethyleneoxide urethane (HEUR) by ultrasonic treatment was studied. The pigment surface modification by the above copolymers was comparatively investigated regarding conventional adsorption as contrasted to an ultrasonic treatment assisted procedure. The course and efficiency of the polymer adsorpption onto the pigment surface was quantified by electrokinetic sonic amplitude measurements. The higher efficiency of the pigment surface coating by the copolymers as achieved by ultrasonic treatment varies with the copolymer architecture and is a consequence of ultrasonically induced pigment surface activation.

Imparting Nonfouling Properties to Chemically Distinct Surfaces with a Single Adsorbing Polymer: A Multimodal Binding Approach.

Surface-active polymers that display nonfouling properties and carry binding groups that can adsorb onto different substrates are highly desirable. We present a postmodification protocol of an active-ester-containing polymer that allows the creation of such a versatile platform. Poly(pentafluorophenyl acrylate) has been postmodified with a fixed grafting ratio of a nonfouling function (mPEG) and various combinations of functional groups, such as amine, silane and catechol, which can provide strong affinity to two model substrates: SiO2 and TiO2 . Adsorption, stability and resistance to nonspecific protein adsorption of the polymer films were studied. A polymer was obtained that maintained its surface functionality under a variety of harsh conditions. EG surface-density calculations show that this strategy generates a denser packing when both negatively and positively charged groups are present within the backbone, and readily allows the fabrication of a broad combinatorial matrix.

Exploring an alternative aqueous lubrication concept for biomedical applications: Hydration lubrication based on O/W emulsions combined with graphene oxide

Water-based lubrication concepts are of high interest for applications that require friction and wear control in a bio-medical environment. In this work, a concept of aqueous lubrication is presented based on hydration of surface active polymers combined with graphene oxide. Three different kinds of surface-active polymers with or without graphene oxide were coated on a CoCrMo alloy surface, and the samples were characterized by ATR and XPS. Hydration lubrication was created from a tailored oil-in-water (O/W) emulsion. Enhanced friction reducing capability was found for the polymeric coatings in combination with graphene oxide. The tribological behaviour of a PEG-lactide coating in emulsion was better than that of PEG coating, indicating the advantage of using hydrophilic and lipophilic group containing surface-active polymers for emulsion lubrication. The overall maximum reduction in friction that was achieved for a sliding contact of coated engineering surfaces from CoCrMo at low sliding velocity and moderate contact pressure was of about 63% compared to uncoated CoCrMo sliding in water at the same operational conditions.

Modifying polyester surfaces with incompatible polymer additives

Surface modification of amorphous PET in incompatible blends is demonstrated using fluorocarbon end-functional polystyrenes. Contact angles with water and decane were consistent with high levels of surface fluorocarbon, even for spin-cast films with no further processing required. Hydrophobicity and lipophobicity were further increased by annealing above the glass transition temperature. High resolution depth profiling using complementary ion beam analysis and specular neutron reflectometry has enabled accurate characterisation of the composition profile of the additive including the minimum in additive concentration found just below the surface enriched layer. This analysis quantified the very low compatibility between the modifying polymer and the amorphous PET and was consistent with the highly segregated nature of the adsorbing species and its sharp interface with the subphase. For these incompatible polymer blends, surfaces enriched with the surface active polymer could coexist at equilibrium with extremely low (∼0.4%) bulk loadings of the additive. This suggests that for thicker films at even lower additive concentrations than the minimum 1% that we studied, it may be possible to achieve efficient surface modification. However, at this concentration, the efficiency of surface modification is limited by the processing conditions. Finally we note that in higher loadings of surface active additive there is clear evidence for lateral phase separation into patterned domains of differing composition. The enhancement in surface properties is due to local reorganisation rather than bulk redistribution of the components within the film, as the composition versus depth distributions of the polymer blend components was observed to be relatively unaffected by annealing.

Laboratory Evaluation and Field Application of a Type of Surface–Active Polymer Oil Displacement Agent

Aimed to obtain a type of oil displacement with both surface activity and polymer performances, this paper based on mixing initiators at low temperatures, prepared a type of anion–nonionic surface–active polymer oil displacement agent (ANSP–1) by introducing polymerizable anion–nonionic surfmer (ANS–1), acrylamide (AM) and acrylic acid (AA). Structure of ANSP–1 was measured by FTIR. Laboratory studies show that ANS–1 occurs graft copolymerization with AM, avoids chromatographic separation, it has better performances on molecular properties, tackifying performance, salt resistance, shear resistance and thermal stability, oil–water interfacial tension can reach 1 10 –1 mN/m. Field application shows that average recovery ratio of the test wells which used ANSP–1 is 11%, is 6.2% higher than the whole area.