Silicone Surfactants Research Articles

Preparation and Properties Improvement of Decynediol-Ethoxylate-Modified Trisiloxane Surfactant.

Silicone surfactants are increasingly used in the industrial field due to their advantages such as low surface energy, stable performance, and good biocompatibility. However, many polyether-modified silicone surfactants' foam stability and easy hydrolysis in non-neutral aqueous systems limit their application in many fields. In this article, the decynediol-ethoxylate chain segment was grafted onto heptamethyltrisiloxane to synthesize a modified trisiloxane surfactant (G2). FT-IR and 1H NMR characterized its structure. Its surface activity, aggregation behavior, and wetting and spreading properties in water were studied by using instruments such as a surface tension meter, transmission electron microscope (TEM), dynamic light scattering (DLS), and contact angle tester. G2 can reduce the surface tension of water to 19.24 mN/m at a lower CMC (40.44 mg/L), and the foaming properties and hydrolysis stability of decynediol-ethoxylate-modified trisiloxane (G2) in water are significantly improved compared with allyl-polyoxyethylene-ether-modified trisiloxane (X5).

Tuning thermal stability of fluorine-free foam by nano-MDH inorganic flame retardant

Foams enhanced by nanoparticles (NPs) have become an important way to develop new type of fluorine-free firefighting foams. This study focuses on thermal stability of foams generated by the mixed dispersion of CoatOsil-77 silicone and BS-12 hydrocarbon surfactants as foaming agent and nano-magnesium hydroxide (nano-MDH) as foam stabilizer. The interaction between nano-MDHs and surfactants were studied. Thermal stability of nano-MDH enhanced foam was explored by investigating drainage and volume attenuation of foam and heat transfer in vertical foam blanket. Stabilization mechanism of nano-MDH enhanced foam under heat was clarified. Results show that nano-MDHs have a weak interaction with the BS-12 molecules and almost has no interaction with the CoatOsil-77 molecules. Initial foam height of mixed dispersion increases at the presence of nano-MDHs, but further increase in the concentration of nano-MDH decreases its foaming ability. At room temperature, foam drainage and coarsening are accelerated by low concentration nano-MDH (1 wt%) and delayed by high concentration nano-MDH (>1 wt%). Meanwhile, foam was strengthened by rising nano-MDH content after exceeding 1 wt%. Drainage and volume attenuation of foam and heat transfer in vertical foam blanket were significantly delayed and the corresponding thermal stability was strengthened by nano-MDHs. This study can offer a possibility for tuning thermal stability of fluorine-free foams based on nano-MDHs.

Synthesis and properties of carboxyl-modified polyether block silicone surfactants

Synthesis and properties of carboxyl-modified polyether block silicone surfactants

Aluminium Hydroxide/Graphene-reinforced Rigid Polyurethane Foam Hybrid Composites

In this study, rigid polyurethane foams (RPUF) were successfully modified using 30 wt.% aluminium hydroxides (ATH), 1.0 pphp silicone surfactant, and different concentrations of graphene, using a one-shot one-step foaming method. This study aims to improve the compressive strength, flame retardancy, and thermal properties of RPUF by creating a synergistic effect between ATH and graphene in fire-retardant RPUF hybrid composites. The effects of a fixed amount of ATH and silicone surfactant and various loadings of graphene on RPUF were investigated. The results show that 0.5 wt.% graphene loading confers the best compression performance on the hybrid composite. Their compressive strength value of 12.58 KPa was higher than virgin RPUF (4.07 KPa) and RPUF/ATH (9.89 KPa). FTIR confirmed the functional groups in the virgin RPUF but could not identify new functional groups in most modified composites. The smallest amount of graphene addition (0.5 wt.%) produced a more stable hybrid composite structure. At 3.0 wt.% graphene addition, the maximum decomposition temperature of the RPUF/ATH hybrid composite was recorded (539oC), which was enhanced by 50% compared to virgin RPUF (296oC), and the highest char residue of 17.46% was observed. The incorporation of graphene enhanced the thermal firmness of the hybrid composite. The study also revealed an enhancement in the fire resistance of the hybrid composite. The LOI and UL-94 results showed that incorporating 3.0 wt.% enables increased LOI value and V-0 classification compared to virgin samples. This hybrid composite can be used in high-performance building insulation applications.

Surface activity, wettability and foam properties of quaternary ammonium surfactants with C-F/Si-H double hydrophobic backbone

This paper reported the synthesis of a novel quaternary surfactant (PFAS-Si) containing the C-F/Si-H double hydrophobic skeleton and the surface properties of its aqueous solution, which were investigated in comparison with those of the aqueous solutions of the fluorosurfactant (PFAS-IEt) and silicone surfactant (TMSAC) with similar hydrophobic chain structures. The critical micelle concentration (CMC) and the corresponding surface tension value (γCMC) of the PFAS-Si solution were 0.0612 mmol/L and 21.02 mN/m, respectively, which indicated that the PFAS-Si could substantially reduce the surface tension of water, and showed excellent surface activity. Meanwhile, the thermodynamic parameters of the micellization process, aggregation behavior, wettability, and foam properties of PFAS-Si solutions were systematically investigated. On the TEM negative staining photographs, it can be clearly seen that the aggregates of PFAS-Si in aqueous solution exhibit hollow spherical vesicles. In addition, the PFAS-Si solution exhibited superb wettability, and could achieve wetting of PTFE sheets at a very low concentration (0.168 mmol/L). Not only that, the PFAS-Si solution also had excellent foaming ability and foam stability. This work provided a new preparation idea for the development of high-performance specialty surfactants.

Oil resistivity of fluorine-free foams stabilized by silica nanoparticles and mixture of silicone and hydrocarbon surfactants

Oil resistivity of fluorine-free foams stabilized by silica nanoparticles and mixture of silicone and hydrocarbon surfactants

Experimental Study on Foam Properties of Mixtures of Organic Silicon and Hydrocarbon Surfactants Regulated by Nano-SiO2 Particles

Experimental Study on Foam Properties of Mixtures of Organic Silicon and Hydrocarbon Surfactants Regulated by Nano-SiO2 Particles

Statistical investigation of the experimental variables in the hydrosilylation reaction of a trimethylsiloxy‐terminated poly (methylhydro‐dimethyl)siloxane copolymer and an unsaturated polyethylene glycol using response surface methodology

The hydrosilylation reaction is a suitable route to prepare efficient, transparent, and low‐viscose silicone surfactants with low surface tension. Initial materials, the catalyst used, and experimental conditions are highly effective variables to achieve the maximum efficiency of the reaction, reduce the consumption of the catalyst, and prevent side reactions. To draw a comprehensive conclusion on the effect of these variables, a series of trimethylsiloxy‐terminated poly (methylhydro‐dimethyl)siloxanes copolymer (abbreviated as RSiH with different preceding numbers) and two unsaturated polyethylene glycols (UPEG200 and UPEG400) were selected, and the reactions in the presence of two platinum‐based catalysts, namely, hexachloroplatinic acid and ammonium hexachloroplatinate, were statistically studied by Design of Experiment. After initial pre‐investigations, the amounts of reactant and catalyst were subjected to analysis of variance using response surface methodology (RSM). Based on the results, low‐viscose and low‐surface tension silicone surfactants were obtained using UPEG400, RSiH105, and (NH4)2PtCl6 as catalysts, at temperatures over 170 °C. The best results were obtained with a relatively low concentration of the catalyst between 2.57 × 10−6 and 2.72 × 10−6 equivalent catalyst per UPEG. The relative equivalent ratio of [UPEG]/[RSiH] at the optimum condition was 1.6, which provided a surface tension below 21 mN/m together with a minimum amount of unreacted RSiH (less than 3%). The silicone surfactant was characterized as a pure product by a series of spectroscopic methods, such as FT‐IR and 1H NMR spectroscopies, as well as bromine number index. These excellent properties make this compound a new alternative in various industries.

Surface activity, foamability, and foam stability of binary mixed systems based on siloxane-based Gemini and hydrocarbon surfactants

Aiming to explore the potential of siloxane-based Gemini surfactants in the development of environmentally friendly foam extinguishing agent to address the pollution caused by traditional fluorinated ones. A crucial step is to study the performance of binary mixed systems of siloxane-based Gemini and hydrocarbon surfactants in terms of surface activity, foamability, and foam stability. In this study, binary mixed systems of two types of siloxane-based Gemini surfactants and one siloxane surfactant with four different hydrocarbon surfactants are prepared. Parameters such as surface tension, foam height, drainage time, and coarsening rate are tested. The results show that the siloxane-based Gemini surfactant HY-4000 with double silane chains could effectively reduce the surface tension of hydrocarbon surfactants. In addition, the two types of Gemini surfactants performed better in enhancing the foamability of hydrocarbon surfactants. The siloxane OFX0193 even inhibits the foaming of cationic hydrocarbon surfactant CATC. Besides the HY-4000/APG0180 mixed system, the binary mixed systems of three silicone surfactants with AOS and APG0180 exhibit better foam stability, particularly the systems containing TEGO4100. For the coarsening process of foam bubbles, we develop a predictive model based on previous studies, where the relationship between bubble area and time follows a power function law. The findings of this study could provide guidance for the development of green foam extinguishing agent with siloxane-based Gemini and hydrocarbon surfactants as core components.

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.

Research Progress in Structure Synthesis, Properties, and Applications of Small-Molecule Silicone Surfactants.

Silicone surfactants have garnered significant research attention owing to their superior properties, such as wettability, ductility, and permeability. Small-molecular silicone surfactants with simple molecular structures outperform polymeric silicone surfactants in terms of surface activity, emulsification, wetting, foaming, and other areas. Moreover, silicone surfactants with small molecules exhibit a diverse and rich molecular structure. This review discusses various synthetic routes for the synthesis of different classes of surfactants, including single-chain, "umbrella" structure, double chain, bolaform, Gemini, and stimulus-responsive surfactants. The fundamental surface/interface properties of the synthesized surfactants are also highlighted. Additionally, these surfactants have demonstrated enormous potential in agricultural synergism, drug delivery, mineral flotation, enhanced oil recovery, separation, and extraction, and foam fire-fighting.

Fluorine-free foaming extinguishing agent: Design route, fire extinguishing performance, foam stability mechanism

The development of fluorine-free foaming extinguishing agent, abbreviation FFEA, has become an urgent scientific challenge in the field of fire protection engineering due to the fact that the key component of existing aqueous film-forming foams is listed as a persistent organic pollutant. A study was conducted on foam performance and fire extinguishing efficiency of FFEA prepared by hydrocarbon and silicone surfactants with low-carbon alcohol modulation, using three selected silicone surfactants. The results show that the FFEA, including low-carbon alcohol-modulated Silok8141/SDS and Silok8008/SDS, exhibit low surface tension, good foam stabilization coefficient and long foam drainage time. Laboratory foam extinguishing experiments demonstrate that the FFEA produced by Silok8141/SDS/Isobutanol ternary system has better cooling effect and fire extinguishing performance. And the study of FFEA mechanism reveals that the addition of isobutanol blocks the foam liquid channel and increases the foam stability. The wide applicability of the design route for FFEA prepared by low-carbon alcohol-regulated hydrocarbon and silicone surfactants has been demonstrated.

Study on the inhibition effect and mechanism of N2 twin-fluid water mist with modified chloride compounds on LPG explosion

In order to develop environmontal friendly and high efficient LPG explosion inhibitors, experiments were carried out to investigate the impact of AeO9 (fatty alcohol polyoxyethylene ether) and Sicare2235 (silicone surfactant) surfactants on the suppression effect of N2 twin-fluid water mist containing modified chloride compounds on 6 % LPG/air explosion. Results showed that: The addition of a single surfactant can significantly reduce the surface tension of the droplets and improve the explosion suppression efficiency of N2 twin-fluid water mist containing chloride additives. However, chloride additives have selectivity towards surfactants. There are obvious differences in the synergistic inhibition effect of different chlorides and surfactants. Under the combination of 0.6 % AeO9, 0.06 % Sicare2235 surfactants and chloride additives, the increase in surface tension will weaken the physical explosion suppression effect and lead to the phenomenon of explosion enhancement. The results of chemical kinetics simulations indicate that, in comparison to a single explosion suppressant, the chlorine-containing compound N2 twin-fluid water mist effectively lowers the adiabatic flame temperature and the concentration of key free radicals H, OH and O. The reaction CH3 + H + M = CH3OH + M plays a pivotal role in reducing the adiabatic flame temperature during LPG explosion.

Synthesis and surface activity of two novel phosphate silicone surfactants

Two phosphate amphoteric surfactants based on silicone were synthesized. Phosphate Gemini surfactant ((C12P2)2Si2) with disiloxane as bridging group and double-chain surfactant (C12P2Si3) with hydrophobic hydrocarbon chain and trisiloxane were prepared by hydrolysis reaction, Kabachnik-Fields reaction, and quaternization reaction. FT-IR, 1H NMR and TGA confirmed the chemical structure and thermal stability of the synthesised (C12P2)2Si2 and C12P2Si3. The physicochemical behavior at the air–liquid interface was investigated. The results showed that the critical micelle concentration (CMC) values of (C12P2)2Si2 and C12P2Si3 are 0.53 and 0.78 mmol/L, respectively. The two new surfactants had surface tension at CMC equal to approximately 28 mN/m and their surface tension varied with temperature and electrolyte (NaCl, CaCl2, and MgCl2) concentration. At high temperatures and with high concentration electrolytes, they exhibited good air–liquid interfacial activity. In addition, the size of the aggregates of the surfactants in aqueous solutions above CMC was determined by the dynamic light scattering (DLS) measurements.

Oleo-sheets and omni-sheets: Fabric-like superabsorbers for oil, water, or any solvent

Materials that can selectively absorb oil from water could be used to clear oil spills, but such absorbents are typically either in the form of powders or small, bulky solids. In homes and labs, spills of oil are absorbed with cloth or paper towels, which are flexible and foldable, but exhibit poor absorbency. There is hence a need for fabric-like sheets that can absorb considerable oil, and here, we report the synthesis of such oleo-sheets by templating organofoams. A foam of CO2 bubbles in a water-in-oil emulsion is first created, with the bubbles stabilized by a silicone surfactant. Monomers in the oil phase (alkyl and urethane acrylates) are then polymerized rapidly at room temperature to give a porous gel. By ambient drying this gel, we make oleo-sheets (∼10 × 7 × 0.4 cm in size) and oleo-sponges (size ∼2 × 2 × 1 cm), which are both soft, pliable materials with interconnected pores. These materials are hydrophobic (water contact angle ∼130°) and they selectively absorb a range of oils (organic solvents) from water. Their absorption capacity (> 50 g/g) exceeds that of commercial absorbents like polyurethane sponges or cloth pads. We also make a magnetic oleo-sponge – after such a sponge absorbs oil, it can be lifted up by a magnet. Lastly, we create an omni-sheet with two distinct sides, one that selectively absorbs oil while the other does the same for water. Thus, the omni-sheet can pick up any spilled liquid. The materials reported here are likely to find application in cleaning up spills due to their unique combination of convenient form factor, robust mechanical properties, and excellent absorbency. Moreover, our synthesis technique can be easily scaled up as it is simple and energy-efficient (since it does not involve freeze-drying) and environment-friendly.

Effect of nanoparticles and silicone surfactants on the foam properties and wettability of dust removal foam

Foam has been widely used in coal mine dust control. However, its instability is still an issue in its application, and some surfactants components in foaming agents, such as fluorocarbons, are harmful to the environment. In this study, the environmentally friendly alkyl glycoside(APG0814) and cetyltrimethylammonium bromide (CTAB) were used as the foaming agents, and modified hydrophilic SiO2 nanoparticles were added to improve foam stability. Also, the surface tension, foam properties, contact angle and intermolecular interaction of APG0814/CTAB/SiO2 dispersion were studied. The experimental results showed that the appropriate concentration of CTAB combined with nanoparticles played a key role in stabilizing the foam. The surface tension of the foaming liquid increased with the increase in nanoparticles and CTAB, leading to the deterioration of foaming properties. The silicone surfactant GT-248 was added to the APG0814/CTAB/SiO2 dispersion to further improve the surface activity of the foaming agent, and the effects of the silicone surfactant on the surface tension, foam properties, and wettability were studied systematically. The experimental results showed that the surface tension of the foaming agent decreased, and the foaming and wettability increased with the increase in silicone surfactant concentration. By the synergistic action of nanoparticles and surfactants, long-lasting and stable foam, fast coal dust deposition rate and low contact angle can be obtained. Among them, 0.8 wt%GT-248 was added to achieve the best surface activity, foaming ability and wettability. These fundamental results might guide the application of silicone surfactants combined with nanoparticle-hydrocarbon surfactants in mine dust control.

Adsorption and Aggregation Behavior in Aqueous Solution of Tetrasiloxane-based Carboxylate Surfactants via "Thiol-ene" Photochemical Reaction.

Anionic silicone surfactants have long been a neglected field. In this paper three anionic silicone surfactants were synthesized first time from dichloromethylvinylsilane through hydrolysis-condensation, "thiol-ene" photo- chemical and then salting reaction. The critical aggregate concentration (CAC), surface tension, minimum surface area per surfactant molecule and surface pressure at CAC were studied by both surface tension and electrical conductivity. The results showed that they had significant surface activity at the gas/liquid interface and were capable to reduce the surface tension of water to approximately 20 mN m-1 . The results of transmission electron microscopy showed that the three silicone surfactants self-assembled into spherical aggregates of uniform size in aqueous solution above the CAC. The dynamic light scattering results demonstrated that the size of the aggregates was determined to be in the range from 60 to 300 nm at 0.05 mol L-1 and the order of the size of the aggregates is (Me3 SiO)3 SiCO2 Li<(Me3 SiO)3 SiCO2 Na<(Me3 SiO)3 SiCO2 K.

Study on wetting mechanism of nonionic silicone surfactant on coal dust

Coal dust disasters are serious in coal mining. The use of nonionic surfactants can effectively improve the wettability of coal dust and reduce the content of suspended coal dust in the air. For the problem of low wettability of ordinary surfactants, this paper selects silicone surfactants with high surface activity and low surface tension to improve the wetting ability of coal dust. To explore the wettability of nonionic silicone surfactants on coal dust, the effects of six nonionic silicone surfactants on the wettability of coal dust surfaces were studied by experiments. The test objects were four kinds of coal samples with different metamorphic degrees. The surface tension, wetting time, and contact angle experiments were carried out, and the critical micelle concentration and the expansion coefficient of the coal surface were calculated. The wetting time of the compound solution was measured to verify the synergistic effect of the compound solution. The results show that: 6 # has the best wetting effect on coal dust, followed by 4 # and 2 #; The order of surface tension is: 1 # < 3 # < 4 # < 6 # < 5 # < 2 #, the surface tension of 1 # is the lowest (19.962 mN/m); 1 # and 4 # are easier to spread on the surface of coal dust, the spreading coefficient of coking coal is the largest and the contact angle is the smallest, which is 18.8°. The 4 # and 6 # with a mass ratio of 8:2 were compounded. The compound surfactant solution had a significant synergistic effect. Compared with the monomer surfactant solution, the wettability of long-flame coal and coking coal increased by 15.14% and 10.00%, respectively. The results of this study can provide reference and experimental support for the development of high-efficiency dust suppressants based on silicone surfactants.

The Effect of NCO Content in Polyurethane Foam for Automotive Instrument Panel

A thermoplastic polyurethane (TPU) series for automotive panels with high durability have been newly synthesized using the reacting process based on polyester polyol (BTG), polycaprolactone triol (PCL), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and 1,4-butanediol chain extender as a function of NCO/OH ratio (NCO index). The dependence of varying NCO index of synthesized TPUs on tensile strength and hardness have evaluated. To form PU foams with suitable rigidity and uniform skin-pores, the optimal synthetic process was controlled precisely by the amount of solvent, foaming agent, silicone surfactant, and catalysts content. A considerable NCO index dependence was observed in the range of 0.96 ≤ NCO index ≤ 0.99 at almost same molecular weight. When NCO index of TPU was 0.98, mechanical properties achieved maximum value due to the uniform open cell structure of molding PU foam. With the ratio of NCO/OH increasing, the hardness of PU foam also increased until 0.98 NCO index while the hardness of 0.99 NCO index decreased. The designed TPU with 0.98 NCO could be a promising formulation for molding foams of automotive skin panels and seating.

Preparation, Characterization, and Properties of Alkali-Resistant and Hydrolysis-Resistant Silicone Surfactant

It is a challenge to research and develop silicon surfactants with good acid and alkali stability. In the present paper, methylpropenyl polyether modified nonionic silicone surfactant (MPNTS), an alkali-resistant and hydrolysis-resistant silicone surfactant, was synthesized by hydrosilylation of 1,1,1,3,5,5,5-heptamethyl trisiloxane (MDHM) and methylpropenyl polyether (EO(7)). The polyether segments are grafted onto the main chain of organosilicon heptamethyl trisiloxane at a molar ratio of 1:1.05 (n(Si-H):n(C=C)). To evidence product formation, the MPNTS were analyzed by FT-IR and 1H NMR spectroscopy. The surface tension of NPNTS is 18.68 mN/m, and the CMC value is 78 mg/L by a contact angle tester. MPTNS shows hydrolytic stability and maintains that it could keep surface activity after standing for 60 days at pH = 7–10. The compatibility performance analysis shows that MPNTS has good compatibility and synergy with cationic, anionic, and nonionic surfactants, and it reveals the application prospects in daily chemicals, agricultural adjuvants, and other products.