Synthesis of novel oil-soluble fluorinated surfactants via Wittig-Horner reaction

In this paper, the synthesis and characterization of novel oil-soluble fluorinated surfactants were reported. Both Wittig and Wittig-Horner reaction were used for constructing the perfluorinated branch-chain structure, and the latter provided a better method through a three-step synthesis route which was easy worked up and low cost. The surface tension of novel products in toluene, n-hexane and nitromethane with concentrations of 0.1?mol/L, 0.05?mol/L, 0.025?mol/L, 0.0125?mol/L, 0.00625?mol/L and 0?mol/L were examined. The surface tension research of these surfactants showed that they can reduce the surface tension of organic reagents dramatically. For example, compound 1e can reduce the surface tension of nitromethane from 36.6?mN/m to 24.2?mN/m in the concentration of 0.1?mol/L, and the surface tension of toluene was reduced from 28.0?mN/m to 22.7?mN/m when the concentration of compound 1a was 0.1?mol/L.     

Synthesis and combined properties of novel fluorinated cationic surfactants derived from hexafluoropropylene dimer

Three novel fluorinated surfactants with branched short fluorinated tails as hydrophobic groups, ammonium oxide as polar groups are prepared. Surface tension measurement shows that these fluorinated surfactants are ideal compounds to design new formulations in fire-fighting field.     

Surface properties and aggregate morphology of partially fluorinated carboxylate-type anionic gemini surfactants

Three anionic homologues of a novel partially fluorinated carboxylate-type anionic gemini surfactant, N,N′-di(3-perfluoroalkyl-2-hydroxypropyl)-N,N′-diacetic acid ethylenediamine (2 edda, where n represents the number of carbon atoms in the fluorocarbon chain (4, 6, and 8)) were synthesized. In these present gemini surfactants, the relatively small carboxylic acid moieties form hydrophilic head groups. The surface properties or structures of the aggregates of these surfactants are strongly influenced by the nonflexible fluorocarbons and small head groups; this is because these surfactants have a closely packed molecular structure. The equilibrium surface tension properties of these surfactants were measured at 298.2 K for various fluorocarbon chain lengths. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain lengths for 2 edda (n = 4, 6, and 8) showed a minimum for n = 6. Furthermore, the lowest surface tension of 2 edda at the cmc was 16.4 mN m⁻¹. Such unique behavior has not been observed even in the other fluorinated surfactants. Changes in the shapes and sizes of these surfactant aggregate with concentration were investigated by dynamic light scattering and transmission electron microscopy (TEM). The TEM micrographs showed that in an aqueous alkali solution, 2 edda mainly formed aggregates with stringlike (n = 4), cagelike (n = 6), and distorted bilayer structures (n = 8). The morphological changes in the aggregates were affected by the molecular structure composed of nonflexible fluorocarbon chains and flexible hydrocarbon chains.     

Synthesis and surface activities of organic solvent-soluble fluorinated surfactants

A variety of fluorinated surfactants soluble in organic solvent were prepared, including C₈F₁₇SO₂NHC_nH_2n+1 (n = 2, 4, 6, 8, 10), C₈F₁₇SO₂NHR (R = C₆H₁₁, C₆H₅), C₈F₁₇SO₂N(C_nH_2n+1)₂ (n = 1, 2, 3, 4) and C₈F₁₇SO₂NH(CH₂)_nNHO₂SC₈F₁₇ (n = 6, 10). Their surface activities in various organic solvents were determined by surface tension measurement. The results showed that these fluorinated surfactants can reduce the surface tension of both polar and non-polar organic solvents. In general, organic solvents with strong polarity or long alkyl chain are beneficial to increase the surface activity of these polar fluorinated surfactants. By comparing fluorinated surfactants with the same fluorocarbon segment and connecting group, C₈F₁₇SO₂N(C_nH_2n+1)₂ (n = 1, 2, 3, 4) showed lower surface activity in organic solvents than C₈F₁₇SO₂NHC_nH_2n+1 (n = 2, 4, 6, 8) with an equal carbon number of the solvophilic group. Through surface tension vs. concentration curves given for N-octyl perfluorooctanesulfonamide in various organic solvents, a break point like the critical micelle concentration of ordinary surfactants in aqueous solutions was observed, and the effect of the different types of organic solvents on adsorption and aggregation behavior was also studied.     

Synthesis of a novel type of hybrid fluorocarbon ionic surfactants containing polyoxyethlene chain

A novel type of hybrid ionic surfactants containing oxyethylene chain and fluorocarbon chain in one molecule, n-C₈F₁₇SO₃⁻N⁺(C₂H₅)₃(CH₂CH₂O)_nH (n = 4.0, ∼4.1, 8.7, 13.2, 17.8, 22.3), were prepared. The compounds were achieved from the reaction of polyethylene glycol and perfluorooctanesulfonyl fluoride in the presence of Et₃N. The evaluation of their behavior at the air-water interface has been studied from measurements of surface tension versus variation of concentration, and the properties of the hybrid surfactants are not consistent with the empirical rule observed from the fluorinated nonionic surfactant.     

Mixed micellization and surface properties of non-ionic/cationic surfactants

We investigate the surface properties of aqueous binary mixtures of our cationic surfactant O-dodecyl-N,N′-diisopropylisourea hydrochloride (ISO-DIC C₁₂) with commercially available nonionic surfactant polyoxyethylene p-(1,1,3,3-tetramethylbutyl)phenyl ether (TritonX-100) at different temperatures (288 to 303?K). The micellization behavior of the binary systems is studied by determining the surface tension and other important physicochemical parameters, such as the critical micelle concentration (CMC), surface tension at the CMC(γ_cmc), Krafft Temperature (T_K), maximum excess concentration (Γ_max), minimum surface area per molecule (A_min), surface pressure at the CMC (П_cmc), and the adsorption efficiency (pC20) at the air/water interface. The study has additionally covered the calculation of thermodynamic parameters of micellization, including the standard Gibbs free energy, the standard enthalpy, the standard entropy, the free energy, and the Gibbs free energy of adsorption at air/water interface. The CMC values of the binary systems determined by experimental data are used to evaluate the micellar composition in the mixed micelle, the interaction parameter β and the activity coefficients f₁(ISO-DIC C₁₂) and f₂ (polyoxyethylene p-(1,1,3,3-tetramethylbutyl)phenyl ether) using the theoretical treatment proposed by Clint and Rubingh. Our results reveal that the proposed binary systems possess enhanced surface activity compared to those of the individual surfactants.     

Novel highly fluorinated sulfamates: synthesis and evaluation of their surfactant properties

Two synthetic pathways have been elaborated to prepare new series of highly fluorinated sulfamates with excellent yields. Surface tension measurements at the air/water interface showed that these compounds constitute new excellent non-ionic surfactants exhibiting high surface activity in the range of the best non-ionic fluoro surfactants already described in the literature. The most important feature of this work is that, in comparison with the classical non-ionic fluoro surfactants, these sulfamates are easily synthesized in a monodisperse form from classical and relatively non-toxic starting materials. The critical micelle concentration (CMC), the maximum surface excess concentration (Γ) and the minimum area per molecule (a) have been calculated from the surface tension measurements on surfactant aqueous solutions. Relationships have been established between the length of both the fluorinated tail and hydrocarbon spacer linking the hydrophobic tail to the hydrophilic head, and the interfacial properties.     

Synthesis and unusual properties of novel alkylbenzene sulfonate gemini surfactants

Seven new dialkyldibenzene disulfonate gemini surfactants have been synthesised. The physico-chemical properties such as their surface tensions, krafft temperatures and melting temperatures have been measured. It was found that the anionic gemini surfactants showed some aberrant properties. The results determined by drop-volume method indicated that surfactants Id, Ie at 25 °C and IIb at 50 °C showed no cmc and lowered surface tension of water hardly despite their seemingly favorable amphiphilic components. However, the three surfactants showed a sharp cmc and good surface activity with the increment of temperature. Surfactant Ie with two longer chains had a higher cmc than that for shorter chain surfactant Id. Furthermore, for this class of anionic gemini surfactants, the spacer carbon number had more important effects than the alkyl chain carbon number on their krafft temperatures and melting temperatures.     

Protein-surfactant interaction: differences between fluorinated and hydrogenated surfactants

The interactions of proteins with fluorinated/hydrogenated surfactants were investigated by circular dichroism and turbidity measurement. Pairs of fluorinated and hydrogenated surfactants with similar critical micelle concentrations (cmc), including sodium perfluorooctanoate/sodium decylsulfate and lithium perfluorononanoate/sodium dodecylsulfate were compared in view of their interactions with proteins including BSA, lysozyme, β-lactoglobulin and ubiquitin. It was found that fluorinated surfactants exhibited stronger interactions with proteins than hydrogenated ones, which, however, depended on the structures of both proteins and surfactant molecules. If the proteins are very stable, or the surfactant–protein interactions are very strong, such differences between the two kinds of surfactants might be indistinguishable.     

Determination of nucleic acid based on increased resonance light-scattering of fluorinated surfactants

Two novel surfactants perfluoroalkanesulfonyl quaternary ammonium iodides (FC134) and potassium perfluorooctanesulfonate (FC95) were successfully used as new probes for detection of DNA by resonance light-scattering (RLS) technique. Resonance light-scattering characteristics of the binding of fluorinated surfactants FC134 and FC95 to calf thymus nucleic acid (ctDNA) were studied. After DNA was added, aggregation of FC134 on the molecular surface of DNA in the pH 3.0-6.0 and aggregation of FC95 on the surface of DNA in the pH 3.5-6.0 occurred, both of which resulted in an enhanced resonance light-scattering peak at 370 nm. The intensity of resonance light-scattering was found to be proportional to the concentration of DNA. The determination limits were 3.5 and 20.0 μg L⁻¹, respectively. UV-vis spectra and IR-spectra both proved the binding of fluorinated surfactants to DNA.     

Segregation phenomena in micelles from mixtures of fluorinated and hydrogenated surfactants

Mixtures of hydrogenated and fluorinated surfactants are known to form either mixed or segregated micelles: the conclusions are much dependant on the precision of the experimental measurements and on the model used for interpretation. Recently, mixed surfactant solutions were probed at the micellar or molecular level by SANS, fluorescence or NMR. It leads to an intermediate structure for the mixed micelles with an intramicellar segregation of the fluorinated and hydrogenated surfactant.This intramicellar segregation was also observed in a variety of more complex systems which are rapidly surveyed in the second part.     

Study on the Langmuir aggregation of fluorinated surfactants on protein

The microphase adsorption-spectral correction (MPASC) technique was described and applied to the study of the interactions of fluorinated surfactants such as potassium perfluorooctanesulfonate (PFOS) and potassium perfluorobutanesulfonate (PFBS) with human serum albumin (HSA). Sodium octanesulfonate (SOS) was also studied as non-fluorinated surfactant. The aggregation of PFOS, PFBS and SOS obeys the Langmuir monolayer adsorption. The results show that the adsorption ratios of surfactants to HSA are PFOS:HSA = 120:1, PFBS:HSA = 205:1 and SOS:HSA = 18:1. The adsorption constants are K_PFOS-HSA = 5.01 × 10³, K_PFBS-HSA = 9.79 × 10² and K_SOS-HSA = 4.03 × 10³. The detection limits are 2.7 mg/L for BSA using PFOS, 3.1 mg/L using PFBS and 3.1 mg/L using SOS. It was found that fluorinated surfactant exhibited stronger interaction with protein than hydrogenated one, and fluorinated surfactant with long hydrophobic chain exhibited stronger interaction with protein than that with short hydrophobic chain.     

Synthesis and characterization on a novel series of protic pyrrolidinium surfactants

<正>A novel series of protic tertiary pyrrolidinium surfactants were prepared and characterized by different techniques.These compounds show good conductivity and efficient ability to reduce surface tension.Thermogravimetric analysis proves their high thermal stability at decomposition temperatures over 250℃.Their lyotropic and thermotropic liquid crystalline properties are also discussed.     

Synthesis and surface properties of a series of surfactants based on O-alkyl and O-perfluoro-N,N′-diisopropylisoureas

O-Dodecyl-N,N′-diisopropylisourea and O-tridecafluorooctyl-N,N′-diisopropylisourea were synthesized by reaction of hydrogenated or fluorinated alcohols onto diisopropylcarbodiimide in quasi-quantitative yields. Adding various hydrogen halides (HCl, HBr, or HI) onto these isoureas enabled one to obtain isoureas hydrohalides with tensioactive properties. The surface properties of both series of hydrogenated and fluorinated surfactants were studied and compared. The influence of the counter-ions onto the surface properties showed that the tensioactive properties were improved in the following increasing order: I < Cl < Br. Fluorinated isourea hydrohalides exhibited better surfactant properties than their hydrogenated homologues.     

Synthesis and properties of cationic surfactants with tuned hydrophylicity

A series of pyridinium-based cationic surfactants has been synthesised and their amphiphilic properties have been studied by conductivity and surface tension measurements. The modification of the substitution pattern on the pyridinium ring by hydrophobic moieties (methyl vs. hydrogen and presence or not of condensed benzene ring) gave the opportunity to investigate structure–activity relationships. Characterization by conductivity and surface tension measurements shed light on the behaviour at the air/water interface and in the micellar environment. In particular, the tendency to form ion pairs at very low concentration was evidenced for all the surfactants substituted on the ring, but not for the simple pyridinium ones. The formation of ion pairs affects both the conductivity and the surface tension plots, showing that a series of steps is involved during the adsorption to the air/water surface. An attempt was made to qualify the single steps in the adsorption at the surface layer. Those steps were attributed to different chemical species (free surfactant ions or ion pairs) and to different arrangements of the surfactant. This work also represents a contribution of investigation at very low surfactant concentrations and high surface tension values.     

Synthesis, characterization and properties of a novel fluorinated polyurethane

A novel fluorinated polyurethane (FPU) was prepared by fluorinated polyether glycol (PTMG-g-HFP) as a soft segment, 1,6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) as a hard segment and 1,4-butanodiol (BDO) as a chain extender. Fourier transform infrared spectroscopy (FTIR), ¹H NMR, ¹³C NMR and gel permeation chromatography (GPC) were used to characterize the structure of the fluorinated polyurethane. The thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by thermogravimetric analysis (TGA). X-ray photoelectron spectroscopy (XPS) analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU. And the mechanical properties of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were also measured. Chemical resistance of polyurethane films was estimated through spot tests with different solvents. The results showed that FPU had high thermal stability, strain-hardening property and good chemical resistance. The XPS measurements showed the fluorine enrichment on the surface of FPU.     

Surface and fluorescence properties of a novel fluorescent surfactant

A novel kind of fluorescent surfactant having 7-hydroxylcoumarin group in the long alkyl chain was synthesized. The critical micelle concentration (CMC), surface tension (γ_cmc) at CMC and absorption, fluorescence properties of this product were determined. From the variations of fluorescence spectra in different solvents, it is observed that the polarity and dielectric constant of the solvents play important roles in the maximum fluorescence intensity and wavelength. Moreover, the surprised exhibition of two fluorescence bands in neutral and alkaline solutions has been attributed to the superexciplex formation of the product molecules. Also, the lower product concentration measuring the fluorescence properties as well as the supposed configuration of hydrogen bond of the product indicate that the larger aggregations cannot exist in alkaline solutions. The superexciplex is a possibility with two or more polar excited molecules together to form an excited state association.     

Syntheses of novel delocalized cations and fluorinated anions,new fluorinated solvents and additives for lithium ion batteries

To improve the properties of rechargeable lithium ion batteries, like conductivity, SEI-formation, thermal and electrochemical stability, low and high temperature performance and safety new electrolyte salts, novel solvents (co-solvents) and additives have been synthesized. All new anions, solvents and additives contain fluorine proving the importance of this element for the electrolyte system. Tetrafluoroborates having bulky delocalized nitrogen-, phosphorus and sulfur-centered counter-cations containing tetramethylguanidyl substituents, like [(Me₂N)₂CNC(NMe₂)₂]⁺, have been prepared to improve the conductivity in polymer electrolytes. The hitherto unknown lithium sulfonate, MeOCF₂CF₂SO₃Li, has been successfully synthesized along with further analogs, and also MeOCF₂CF(CF₃)SO₃Li was obtained, both from precursors, FO₂SCF₂C(O)F or FO₂SCF(CF₃)C(O)F accessible by ring opening reactions from the respective sultones. For the lithium salt CF₃OCF(CF₃)SO₃Li, a new simple synthetic pathway was found where CF₃OCFCF₂ and SO₂F₂ were used as precursors. Novel possible redox shuttles, namely (CF₃)₅C₆OLi and fluorinated pyridine-N-oxides have been prepared. A neutral cyclic carben-PF₅ adduct turned out to be a very effective overcharge protection additive. The family of cyclic and acyclic carbonates playing a key-role as electrolyte solvents in lithium ion batteries could be extended by derivatives of 1,1,1,4,4,4-hexafluorobutandiol. Reaction products from perfluoropropene oxide and alcohols, ROC(F)CF₃C(O)OR (R = CH₂CF₃, CH₂CH₂, CH(CF₃)₂) were obtained according to new optimized methods. New cyclic sulfonamides synthesized from FO₂SCF₂C(O)F and FO₂SCF(CF₃)C(O)F could be successfully identified as versatile electrolyte additives.     

Effect of different surfactants on colloidal and polymer properties of fluorinated acrylate latex

Fluorinated acrylate latex was successfully prepared by semi-continuous seeded emulsion polymerization of dodecafluoroheptyl methacrylate (DFMA) with butyl acrylate (BA), methyl methacrylate (MMA) initiated by potassium persulfate in the water. The resultant latexes and their films are characterized with Fourier transform infrared (FTIR) spectrometry, contact angle determinator, dynamic light scattering detector and surface tension determinator. Effect of different surfactants on colloidal and polymer properties of fluorinated acrylate latex was studied. Results show that the latex prepared with sodium dodecyl benzene sulfonate surfactant has the smallest particle size and contact angle but the moderate surface tension. The latex prepared with perfluorooctanesulfonic acid potassium surfactant has the smallest surface tension, moderate particle size but the biggest contact angle. The latex prepared with sodium 2-hydroxy-3-(methacryloyloxy) prop- ane-1-sulfonate surfactant has the biggest particle size and surface tension but moderate contact angle. In addition, the latex prepared with sodium 2-hydroxy-3-(methacryloyloxy) prop- ane-1-sulfonate has higher electrolyte stability.     

Synthesis and properties of gemini-type hydrocarbon-fluorocarbon hybrid surfactants

Gemini-type hybrid surfactants with two fluorocarbon chains connected through a hydrocarbon spacer, F(CF₂)_m(CH₂)₂CH(OSO₃Na)(CH₂)_nCH(OSO₃Na)(CH₂)₂(CF₂)_mF [Fm(Hn)FmOS, m = 4, 6; n = 5, 6, 7, 8)], were synthesized and their surface chemical properties were examined with the aim to have highly functional and highly water-soluble fluorinated surfactants when compared with the conventional fluorinated surfactants. Comparisons of the surface chemical properties of the synthesized gemini-type hybrid surfactants with those of monounit-type hybrid surfactants, F(CF₂)_m(CH₂)₂CH(OSO₃Na)(CH₂)_nH [FmEHnOS, m = 4, 6; n = 3, 5)], revealed that gemination causes a remarkable lowering (about 1/100) in cmc value while it produces little changes in Krafft point (below 0 °C) and surface tension at cmc (γ_cmc).