Polysiloxane Surfactants Research Articles

Environmentally friendly fluorine-free fire extinguishing agent based on the synergistic effect of silicone, hydrocarbon surfactants and foam stabilizers

The environmentally friendly fluorine-free fire extinguishing agent based on the silicone surfactant was developed in order to solve the environmental hazards and bio-accumulative of traditional aqueous film-forming foam (AFFF). The carboxyl modified polyether polysiloxane surfactant (CMPS) was an efficient alternative to fluorocarbon surfactant, which was firstly synthesized via the esterification reaction using hydroxyl-containing polyether modified polysiloxane (HPMS) and maleic anhydride (MA) as raw materials. Then the surface activity, foam properties, micellar morphology of the CMPS and four hydrocarbon surfactants, as well as their mixture are evaluated by surface tension, Ross-Miles and cryo-transmission electron microscopy (Cryo-TEM). And the suitable key amount of CMPS and hydrocarbon surfactants added to the extinguishing agent were optimized by orthogonal tests. Moreover, the effect of foam stabilizer on the surface activity, foam property and fire extinguishing performance of fire extinguishing agent are also analyzed. Consequently, a new environmentally friendly fluorine-free fire extinguishing agent was prepared and the surface tension, the interfacial tension, foam properties, bubble morphology, spreading behavior and fire extinguishing mechanism were systematically characterized. The Cryo-TEM results illustrate that the intense interaction among silicone and hydrocarbon molecules exists in the the mixture of CMPS and hydrocarbon surfactants, which is produced through the change of micellar morphology, i.e. microscopic larger spheroidal micelles of CMPS transited to smaller spheroidal micelles and wormlike micelles in the mixed system. The surface tension of synthesized foam extinguishing agent is 22.3 mN/m and the spread coefficient is 0.9 mN/m, which has excellent surface activity and spreading property. The prepared foam extinguishing agent exhibits superior fire-fighting property, which can be attributed to the high surface activity, good foam property and superior foam stability. The research results of this paper lay a theoretical foundation for the research and development of efficient environmentally friendly foam extinguishing agent.

Synthesis of Carboxyl Modified Polyether Polysiloxane Surfactant for the Biodegradable Foam Fire Extinguishing Agents.

It is necessary to develop novel and efficient alternatives to fluorocarbon surfactant and prepare fluorine-free environmentally-friendly fire extinguishing agent. The carboxyl modified polyether polysiloxane surfactant (CMPS) with high surface activity was synthesized via the esterification reaction using hydroxyl-containing polyether modified polysiloxane (HPMS) and maleic anhydride (MA) as raw materials. The process conditions of the esterification reaction were optimized by orthogonal tests, and the optimum process parameters were determined as follows: reaction temperature of 85 °C, reaction time of 4.5 h, isopropyl alcohol content of 20% and the molar ratio of HPMS/MA of 1/1. The chemical structure, surface activity, aggregation behavior, foam properties, wetting properties and electron distribution were systematically investigated. It was found that the carboxyl group was successfully grafted into silicone molecule, and the conjugated system was formed, which changed the interaction force between the molecules and would affect the surface activity of the aqueous solution. The CMPS exhibited excellent surface activity and could effectively reduce the water's surface tension to 18.46 mN/m. The CMPS formed spherical aggregates in aqueous solution, and the contact angle value of CMPS is 15.56°, illustrating that CMPS had excellent hydrophilicity and wetting performance. The CMPS can enhance the foam property and has good stability. The electron distribution results indicate that the introduced carboxyl groups are more inclined towards the negative charge band, which would be conducive to weak the interaction between molecules and improve the surface activity of the solution. Consequently, new foam fire extinguishing agents were prepared by using CMPS as a key component and they exhibited excellent fire-fighting performance. The prepared CMPS would be the optimal alternative to fluorocarbon surfactant and could be applied in foam extinguishing agents.

Effect of siloxane backbone length on the physicochemical properties of gluconamide-modified polysiloxane surfactants

Three isostructural gluconamide-modified polysiloxane (GL@Si) surfactants of varying siloxane backbone lengths (molecular weights) were designed and synthesized via an amidation reaction. Their physicochemical properties and potential applications are discussed herein. Each of the three GL@Sis exhibits good surface activity. The critical aggregation concentrations (CAC) of GL@Sis solutions decrease with increasing siloxane backbone length. Surface tension at the CAC (γCAC) increases with molecular weight. Dynamic surface tension results indicate that lower molecular weight GL@Sis exhibit improved diffusion ability compared to larger GL@Sis. Contact angle measurements indicate that lower molecular weights and higher concentrations of GL@Sis produce smaller equilibrium contact angles. Emulsifying measurements reveal that GL@Sis forms better emulsions with soybean oil than liquid paraffin, with lower molecular weight GL@Sis demonstrating superior emulsifying capabilities. Moreover, GL@Sis exhibit good foamability and foam stability. GL@Sis possess smoothness, softness, and anti-yellowing properties. The fiber surface is visually smooth after finishing with GL@Si4-8.

Preparation, characterization, and properties of novel meglumine-based polysiloxane surfactants

A series of meglumine-based polysiloxane surfactants, (PSim-n) with different numbers of meglumine branches were prepared. The formed surfactants were characterized by FT-IR and NMR techniques. Physiochemical properties, such as surface activity, aggregation behavior, and wettability, were closely examined and used to differentiate the various samples. The findings demonstrate that PSim-n surfactants possess high surface activity and can wet-out a parafilm surface at all but extremely low concentrations. Furthermore, PSi6-4, the surfactant with the highest meglumine concentration, can form larger complex aggregates in aqueous solutions.

Fogging loads of California fresh citrus for control of Asian citrus psyllid, Diaphorina citri :

Contact insecticides are commonly applied as fogs to disinfest and disinfect spaces. Recently, these fogs have been adapted to treat commodity within the spaces, and much has been learned regarding the efficacy of this process. When considering fresh citrus in California, fogs are applied to control both insects and microbes. One insect pest, the Asian citrus psyllid (ACP), Diaphorina citri, is a quarantine pest in California and limiting its geographic distribution is a major goal of the California citrus industry. While a variety of phytosanitary measures can be used to control adult ACP once fruit is at a packing house, ultimately, a treatment must be developed to disinfest field-run fruit prior to its exiting the grove. High-pressure fogging with 1,100-L of an aqueous mixture containing 0.2% Evergreen® (6% pyrethrins & 60% piperonyl butoxide) and 0.5% (v/v) BreakThru® (polysiloxane surfactant) was explored in laboratory-, pilot-, and commercial-scale trials as an approach to disinfest a 48-bin trailer load of fresh citrus. Laboratory-scale studies were conducted to quantify, and subsequently model, insecticidal coverage as a function of temperature, surface area, droplet size, and fog volume. Results are discussed in the context of experimental variability across confirmatory trials and continued efforts to optimize the technical and economic feasibility of fogging as a postharvest control strategy.

Optimization of Aqueous Nano Ceramic Ink and Printing Characterization for Digital Ink-Jet Printing

The advantage of ceramic ink-jet printing technology is the accurate and fast printing process of digital images for various products. For digital ink-jet printing applications, ceramic ink requires proper viscosity and surface tension, along with dispersion stability of the inorganic pigments. The purpose of this study is the formulation of an environment-friendly ceramic ink with a water-based system; using nano-sized CoAl2O4 pigment as a raw material, ink should have dispersion stability to prevent nozzle clogging during ink-jet printing process. In addition, the surface tension of the ceramic ink was optimized with the polysiloxane surfactant according to the surface tension requirement (20 - 45 mN/m) for ceramic ink-jet printing; by adjusting the viscosity with poly ethylene oxide, jetting behavior of the ceramic ink was investigated according to changes in the physical features through drop watcher measurement. Key words: Suspensions, Traditional ceramics, Ink-jet printing, Raw material, Aqueous ceramic ink

Synthesis and solution properties of ionic liquid-type polysiloxane bola surfactants

ABSTRACTThree novel ionic liquid (IL)-type polysiloxane bola surfactants (ATPS-MA, ATPS-EA, and ATPS-PA) were designed and synthesized using a two-step method. Their chemical structures were characterized by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. Their surface activity and aggregation behavior in aqueous solution were systematically investigated by surface tension measurements, transmission electron microscopy (TEM), and dynamic light scattering (DLS). Surface activity measurement results indicated that the γCMC of the three IL-type polysiloxane surfactants are under 25 mN m−1, and much lower than those of conventional IL hydrocarbon bola surfactants due to the introduction of siloxane group at the end of the hydrophobic chains. TEM and DLS analyses results indicated that the three surfactants can self-assemble into spherical micelles with a range from 50 to 300 nm, indicating potential uses as model systems for biomembranes and vehicles for drug delivery.

Polyglycerol modified polysiloxane surfactants: Their adsorption and aggregation behavior in aqueous solution

Abstract A simple process to synthesize polyglycerol modified polysiloxane surfactants has been carried out applying a “grafting-to” approach. After formation of allyl polyglycerol ether (APGE) from diglycerol (DGY) and allyl glycidyl ether (AGE), polysiloxane modified by designed number of polyglycerol groups (PHMS-APGE) were obtained by connecting the APGE structure to different Si H functionalized polyhydromethyl siloxane (PHMS). The synthesized APGE-PHMS were characterized by IR and 1H NMR. Solubility measurements showed that the solubility of the as-prepared polymers increased in polar solvents with the increasing of the amount of hydrophilic APGE groups. Furthermore, the surface activity, surface adsorption, aggregation and spreading behaviors of APGE-PHMS were investigated utilizing surface tension measurements, dynamic light scattering (DLS), transmission electron microscopy (TEM) and contact angle measurements. The results showed that critical aggregation concentration (CAC) and the time needed to reach adsorption equilibrium on water surface decrease systematically with the increase in the number of APGE groups. These polymers in aqueous solutions could aggregate to form spherical assemblies. Moreover, the spreading behavior of these polymers on low energy surface was found to be influenced by the number of hydrophilic APGE groups.

Synthesis, characterization and surface properties of amino-glycopolysiloxane

Three series of amino-grafted polysiloxane surfactants with well-defined amphiphilic structures, were successfully synthesized and characterized by FT-IR and 1H NMR. Their surface activities and aggregation behavior in aqueous solution were investigated by surface tension measurements for different concentrations at 25°C. Various surface properties of the synthesized surfactants, particularly interfacial tension, foaming power, emulsification power and surface parameters like, critical micelle concentration (CMC), effectiveness (πCMC), efficiency (PC20) as well as maximum surface excess (Γmax) and minimum surface area (Amin) were evaluated. Micellization and adsorption in liquid/air interfaces thermodynamics were investigated. All compounds prepared showed good surface properties, surface parameters and thermodynamic parameters.

A polysiloxane surfactant dissolves a poorly soluble drug (nystatin) in water

The aqueous dissolution of a poorly soluble drug nystatin (Nys) was achieved by a simple, excipient-free procedure using a tromethamol-modified polysiloxane (ST) as surfactant. Long-term stable Nys aqueous formulation was prepared and investigated by different methods, in order to understand the mechanism of drug solubilization. The cryo-TEM analysis revealed the presence of soft vesicles in the Nyst_ST solution. According to TEM measurements, the drug is contained in the hydrophobic layer of the surfactant vesicles. The dynamic light scattering (DLS) measurements on Nys_ST showed a main population around 134nm having the Zeta potential of 33.3mV. FT-IR, UV–vis, and thermogravimetric (TG-DTG-DTA) data point toward physical encapsulation, accompanied by a decrease of H-bonding between the drug molecules. The antifungal activity tested in vitro toward four yeast strains was seriously improved compared to the aqueous dispersion of the native drug, although the availability was diminished compared to DMSO solution.

Fast and reversible microscale formation of columns in carbon nanotube suspensions

Homogeneous carbon nanotube suspensions are studied in the semidilute regime, which is permitted by the use of an effective polysiloxane surfactant, PySi70, as a liquid matrix. We study such suspensions under an AC electric field by optical microscopy, transient light transmission and impedance spectroscopy. Optical microscopy shows the formation of long-range microscale columnar order as a result of a fast field-induced phase separation. The aggregation process is found to be reversible and repeatable, with nanotubes re-dispersing into a homogeneous solution, in a diffusive manner, in the seconds following removal of the electric field. The suggested role of the induced dipolar forces is consistent with the relatively fast columnar formation and characteristic concentration of maximum field-response. The equilibrium columnar structure provides fast field-induced control of the transparency and dielectric response, while avoiding electrical breakdown.

The Performance of Polyether Modified Polysiloxane

According to the corresponding national standard methods, the surface tension, HLB value, CMC value and emulsification performance of the product were determined. Compare the hydrolytic stability with other three kinds of organic silicon surfactants, the experiment result shows that the hydrolytic stability of product is better than the similar products. The key to reduce the hydrolysis rate of polyether modified polysiloxane surfactant is to reduce the contact of polysiloxane chain in surfactant molecules with water solution. For methoxy-terminated polyether modified polysiloxane, the methyl ether open as the umbrella, which can reduce the contact of polysiloxane chain in surfactant molecules and water solution to a certain extent, so the hydrolysis stability raise.

Synthesis and Solution Properties of Novel Sugar‐Based Polysiloxane Surfactants

AbstractTwo sugar‐based polysiloxane surfactants with well‐defined structures, 3‐(2‐aminoethylamino)propyl functional polysiloxane glucosamide grafted (AEAPFPS‐GA) and 3‐(2‐aminoethylamino)propyl functional polysiloxane lactobionamide grafted (AEAPFPS‐LA), were successfully synthesized and characterized by FT‐IR and 1H NMR. Their surface activities and aggregation behavior in aqueous solution were investigated by surface tension measurements, dynamic light scattering (DLS) and negative‐stain transmission electron microscopy (TEM). The surface tension measurements provided the critical micelle concentration (CMC) and the surface tension at the CMC (γCMC), which revealed that these two surfactants have a much higher surface activity than those of conventional hydrocarbon surfactants. DLS and TEM analysis of the two polysiloxane surfactants aqueous solutions revealed that the AEAPFPS‐GA can self‐assemble into collapsed spherical micelles, and the AEAPFPS‐LA can self‐assemble into spherical micelles.

Synthesis and Properties of Lactobionamide-Based Polysiloxane Surfactant

AbstractA lactobionamide-based polysiloxane surfactant (LBPS) with well-defined structure was prepared via a two-step method. Structure characterization of the LBPS was performed by Fourier Transform Infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H NMR). Surface activity and aggregation behavior in aqueous solution of the LBPS were investigated by surface tension measurements, dynamic light scattering (DLS) and negative-stain transmission electron microscopy (TEM). The results show that the critical micelle concentration (CMC) and surface tension (γCMC) at the CMC in aqueous solution of the LBPS are 7.7 mg · L−1and 27.5 mN · m−1, respectively, and the surfactants can self-assemble into spherical micelles with diameters in the range from 30 to 250 nm.

Polysiloxane Surfactants for the Dispersion of Carbon Nanotubes in Nonpolar Organic Solvents

We develop two new amphiphilic molecules that are shown to act as efficient surfactants for carbon nanotubes in nonpolar organic solvents. The active conjugated groups, which are highly attracted to the graphene nanotube surface, are based on pyrene and porphyrin. We show that relatively short (C18) carbon tails are insufficient to provide stabilization. As our ultimate aim is to disperse and stabilize nanotubes in siloxane matrix (polymer and cross-linked elastomer), both surfactant molecules were made with long siloxane tails to facilitate solubility and steric stabilization. We show that the pyrene-siloxane surfactant is very effective in dispersing multiwall nanotubes, while the porphyrin-siloxane makes single-wall nanotubes soluble, both in petroleum ether and in siloxane matrix.

Effect of salt and pH on surface active properties of comb rake-type polysiloxane surfactants

Comb rake-type polysiloxane surfactants, [PA-oligo(PO- b-EO) series and PA-oligo(PO- b-EO)Me series] were synthesized by the hydrosilylation reaction. To investigate the surface active properties of polysiloxane surfactants that have multiple hydrophobic and hydrophilic groups, the surface tension and sedimentation time of the aqueous surfactant solution were measured. Surface tension and cloud point ( C P) tended to increase with an increase of the EO chain length and a decrease of the PO ratio. The surface tension of siloxane surfactants in the methoxy group was lower than that of the hydroxyl group. Surface tensions at pH 3 and 11 were higher than those in neutral pH values. When the inorganic electrolyte was added into the aqueous solution, the surface tension tended to decrease gradually due to the arrangement of surfactant molecules toward the interface of aqueous solution. The sedimentation time of the aqueous solution tended to decrease with an increase of the EO chain length, and a decrease of PO ratio. The sedimentation time according to the variation of pH values was similar to the results of surface tension.

Synthesis of hydrophilic polymers in supercritical carbon dioxide in the presence of a siloxane‐based macromonomer surfactant: Heterogeneous polymerization of 1‐vinyl‐2 pyrrolidone

AbstractBatch free radical polymerization of 1‐vinyl‐2‐pyrrolidone (VP) in supercritical carbon dioxide (scCO2) was studied in the presence of a reactive polysiloxane surfactant (PDMS‐mMA). Phase behavior investigation showed that when the initial concentration of the surface active macromonomer was higher than 2.5% w/w with respect to the monomer, the reaction mixture, in the absence of efficient stirring, was initially opaque to the visible light, and it slowly turned to an orange tint. Polymerization experiments carried out with surfactant concentration higher than the aforementioned value proceeded with a fast kinetics, and led to the formation of spherical nanoparticles with almost quantitative yields (higher than 98% with a reaction time lower than 70 min). The effect of the concentration of the surface active macromonomer, the initiator and the monomer, and of the density of the fluid phase on the kinetics of the process and on the morphology of the particles was investigated. A marked decrease of the number‐average diameter of the polymer particles with the surfactant concentration was obtained without any particle agglomeration. A dependence on [Initiator]−0.16 of the particle diameter was observed. Such scaling law exhibits an exponent higher than any previously reported for dispersion processes and rather close to those foreseeable on the basis of Smith–Harkins kinetics for emulsion polymerization. Collected experimental results strongly suggest that the polymerization of VP in the presence of PDMS‐mMA could proceed with a nucleation mechanism different from that postulated in pure dispersion polymerization stabilized by graft‐forming surfactants. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 173–185, 2004

Dispersion Copolymerization of Vinyl Monomers in Supercritical Carbon Dioxide

The thermally initiated free-radical dispersion copolymerization of methyl methacrylate (MMA) and N,N-dimethylacrylamide (DMA) in supercritical carbon dioxide has been studied in the presence of polysiloxane surfactants. The formation of a stable latex seems to be related to the presence of at least one reactive end group in the surfactant macromolecule, thus suggesting that anchoring of the stabilizer to the surface of the growing polymer particles occurs through chemical grafting. In the case of a molar ratio of DMA to MMA lower than 0.40, microspherical copolymer particles with yields ranging from 81 to 97% were collected from batch polymerizations carried out at 65 °C and 23−28 MPa using AIBN as an initiator and PDMS-mMA as a surfactant. The effect of conversion on the cumulative composition of the copolymer was investigated at a 0.20 mol/mol DMA/MMA ratio, and this composition, determined through NMR analyses, was found to be roughly constant during the entire process and, at the adopted initial feed...

Phasenverhalten siliziumorganischer Kammpolymerer in wäßriger Lösung / Phase Behaviour of Silicone Surfactants with a Comblike Structure in Aqueous Solution

The phase behaviour of several polymeric siloxane surfactants MD n D ' m (R)M and of a polyoxyethylene trisiloxane MD ' RM in aqueous solutions was studied using different methods. The nonionic polyoxyethylene surfactants have the same backbone, but different polyoxyethylene side chains. All investigated polymers form liquid crystalline phases at concentrations above 50 wt%. These liquid crystalline phases disappear at concentrations above 90 wt% and the systems form isotropic single phase solutions. Cationic, zwitterionic and the more hydrophobic nonionic polysiloxane surfactants form lamellar phases. The liquid crystalline phases were investigated by polarization microscopy and rheological methods. Surface and interfacial tension determinations demonstrated the typical behaviour of surface active compounds. The aggregates formed above the c.m.c. were characterized using static and dynamic light scattering and electric birefringence methods.

Syntheses and properties of surfactants containing organometals: IV. Organo silicone

AbstractThe authors synthesized nonionic surfactants containing dimethylpolysilane, dimethylpolysilmethylene and dimethylopolysiloxane as the hydrophobic groups, and investigated their surface activities. In their ability to lower the aqueous surface tension, the polysiloxane surfactants were the most active, and there is little reason to choose between the other two kinds of surfactants. With regard to the ability of lowering the interfacial tension between water and silicone oil, the polysilmethylene surfactants were most effective when the concentration of aqueous solution was below 0.5 wt %. Above this concentration, however, the polysiloxane surfactants were superior. Also investigated was the lowering of surface tension of nonaqueous polyols and their ability to wet low energy hydrophobic surfaces such as polyethylene.