Gemini Surfactants with Polymethylene Spacer: Supramolecular Structures at Solid Surface and Aggregation in Aqueous Solution

Aggregation of α,ω-bisammonium cationic gemini surfactants with a variable polymethylene spacer and two dodecyl chains has been studied on a solid surface and in aqueous solution. Scanning electron microscopy and dynamic light scattering with the time-resolved fluorescence quenching technique were used for the experiments on the solid surface and in aqueous solution, respectively. As the results from the scanning electron microscopy indicate, the morphology of supramolecular structures of gemini surfactants at the solid surface depends on the spacer length. In aqueous solution, gemini surfactants with spacers consisting of 4, 6, 8, 10, and 12 CH₂ groups form spherical micelles with diameters between 2 and 3.5 nm. Micelles of gemini surfactant with a short ethylene spacer show an increase in size up to 13 nm at the maximum concentration investigated. The aggregation number of micelles determined by time resolved fluorescence quenching was found to be in the range 14–25 for the spacer lengths from 6 to 12 CH₂ groups with only a moderate increase with surfactant concentration. For micelles of gemini surfactants with the short ethylene spacer, the increase of the aggregation number up to 50 at the maximum concentration was observed. The findings support micellar growth of gemini surfactants with short ethylene spacer.     

Synthesis and characterization of glucosamide-based trisiloxane gemini surfactants

A new family of glucosamide-based trisiloxane gemini surfactants of the general formula (CH₂OCH₂)_n (Me₃SiOSiMeR¹OSiMe₃)₂ (where R¹=(CH₂)₃NR²(CH₂)₂NHCO (CHOH)₄CH₂OH; R²=CH₂CH(OH)CH₂OCH₂; and n=0, 1, or 2) was prepared and characterized, both structurally and as aqueous surfactants. The monomer was prepared by amidation of the precursor amine functional trisiloxane with d-gluconic acid δ-lactone. Gemini surfactants were then prepared by the alkylation of the precursor secondary amine with oligoethylene glycol diglycidyl ethers. They were structurally and elemental analysis. Members of this family reduced the surface tension of water to approximately 21 mN/m at concentration levels of 10⁻⁵ mol/L. These gemini compounds showed two critical aggregation concentration values. This behavior resulted from the formation of premicellar aggregates before true micelles were formed.     

Synthesis and Properties of Novel Double-Tail Trisiloxane Surfactants with High Spreading Ability

A new type of double-tail trisiloxane surfactants of the general formula R¹NR²CH₂CH(OH)CH₂O(CH₂CH₂O)xCH₃ (x = 8.4, 12.9, 17.5, 22; R ¹ = Me₃SiOSiMe(CH₂)₃OSiMe₃, R ² = CH₂CH(OH)CH₂OR³, R ³ = CH₂CH(C₂H₅)CH₂(CH₂)₂CH₃) has been synthesized by reacting single-tail trisiloxane surfactants with 2-ethylhexyl glycidyl ether. Their structures were characterized with ¹H-NMR and ¹³C-NMR spectroscopy. These double-tail trisiloxane surfactants reduce the surface tension of water to less than 24 mN/m at a level of 10⁻⁵ mol/L. The spreading ability (SA) of the double-tail trisiloxane surfactant solution on Parafilm (or Ficus microcarpa leaf) surfaces is better than that on polyethylene terephthalate surface. The SA of the solution of the double-tail trisiloxane surfactants 1J with average ethoxy units of 8.4 is far better than the others, and its solution (5.0 × 10⁻³ mol/L) possesses an SA value of over 15 within 10 min on Parafilm and Ficus microcarpa leaf surfaces. The surface tension values of aqueous solutions (1.0 × 10⁻³ mol/L) of the double-tail trisiloxane surfactants 1J are still less than 25 mN/m over 21 days in an acidic environment (pH 4.0) and 139 days in an alkaline environment (pH 10.0), respectively. It is suggested that the SA and hydrolysis resistance of double-tail trisiloxane surfactants are able to be improved by changing the structure of the hydrophobic group, such as increasing the molar ratio of methyl to methylene.     

Synthesis and Aggregation of Novel Sugar-Based Gemini Surfactant with a N,N′-Acetylethylenediamine Spacer in Aqueous Solution

A novel sugar-based Gemini surfactant with a N,N′-acetylethylenediamine spacer (N,N′ (N-dodecyl-2-D-glucosaminyl acetyl) ethylenediamine, Glu(12)-(AA)-Glu(12)), was synthesized with D-(+)-Glucono-1,5-lactone as starting material in three steps. The surfactant's structure was confirmed using ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization mass spectrometry (ESI-MS). The aggregation behavior of Glu(12)-(AA)-Glu(12) in aqueous solution at pH 4.0, 7.0, and 10.0 was investigated by surface tension, dynamic light scattering (DLS), and cryogenic transmission electron microscopic (Cryo-TEM) measurements. The surface tension measurement shows that the critical micelle concentration (CMC) of Glu(12)-(AA)-Glu(12) is at the concentration level of 10⁻⁵ mol·L⁻¹ at 25 °C, which is significantly lower than that of corresponding monomeric sugar-based surfactants. Compared with such sugar-based Gemini surfactants with similar hydrophilic spacers, Glu(12)-(AA)-Glu(12) demonstrated similar or slightly lower surface activity. The CMC value of Glu(12)-(AA)-Glu(12) underwent a slight decrease with the increase of pH. DLS and Cryo-TEM measurements reveal that Glu(12)-(AA)-Glu(12) forms micelles at acidic pH (pH 4.0) and the micelles are transformed into vesicles at neutral or high pH (pH 7.0, 10.0). The microstructural transformation of Glu(12)-(AA)-Glu(12) aggregates is related to the protonation state of its two tertiary amines in the head groups versus pH.     

Synthesis and Surface Properties of Novel Quaternary Ammonium Gemini Surfactants with Polar Head Groups Containing 2-Hydroxypropyl Moieties

The purpose of this paper is to comprehend in-depth the effect of the surfactant structure on its and physicochemical properties such as surface/interfacial properties, foam stability, wettability, and biodegradability. To this end, quaternary ammonium Gemini surfactants, alkanediyl-α,ω-bis[(2-hydroxypropyl)dodecylammonium] dibromide (abbreviated as C_m-n-C_m[iso-Pr(OH)]₂ with m = 12, 14 and n = 2, 3, 4) were synthesized via substitution and quaternization reactions, and their chemical structures were characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (¹HNMR) spectroscopies. The results showed that with the decrease of the spacer length, the surface tension was reduced more strongly, and with the increase of the alkyl tail length, micelles were more easily formed. Besides, the highest surface activity of C₁₄-2-C₁₄[iso-Pr(OH)]₂ was observed by increasing NaCl concentration to 200 g L⁻¹. The temperature had a great influence on thermodynamic parameters of the adsorption and micellization. The interfacial tension between 0.26 g L⁻¹ C₁₄-2-C₁₄[iso-Pr(OH)]₂ solution and oil could reach 0.022 mN m⁻¹. An elongation of the spacer chain in C₁₄-n-C₁₄[iso-Pr(OH)]₂ was unfavorable to foam stability. Besides, the oil-wetted core, which was aged in 0.6 g L⁻¹ C₁₄-2-C₁₄[iso-Pr(OH)]₂ solution, exhibited more hydrophilicity. C_m-n-C_m[iso-Pr(OH)]₂ surfactants produced higher biodegradable rates in river water (≥ 90% after 28 days) than the biodegradable surfactant of international recommendation (71% after 28 days) at 30 °C.     

Synthesis of Quaternary Ammonium Salts with Novel Counterions

The preparations of quaternary ammonium compounds from various tertiary amines and the (environmentally friendly) alkylation agent dimethyl carbonate were carried out. The effects of reaction temperature, reaction time, material mol ratio and solvent dosage on quaternization were examined, and the optimum reaction conditions were determined. Under the optimum conditions, the conversions of mono-alkyl tertiary amines could attain over 99%, while the conversions of di-alkyl tertiary amines reached over 95%. Moreover, a series of quaternary ammonium salts with new counterions (HCO₃, CH₃COO, CH₃CH₂COO, CH₃CH(OH)COO) were synthesized by the hydrolysis of methyl carbonate quaternary ammonium salts or by ion exchange reaction of methyl carbonate quaternary ammonium salts with corresponding acids.     

Synthesis and Properties of Novel Double-Tail Trisiloxane Surfactants

To improve the hydrolysis resistant ability of trisiloxane surfactants, ethoxylated single-tail and double-tail trisiloxane surfactants of the general formulas Me₃SiOSiMeR¹OSiMe₃ (R ¹ = (CH₂)₃NHCH₂CH(OH)CH₂(OCH₂CH₂) _x OCH₃; x = 8.4, 12.9, 17.5, 22) and Me₃SiOSiMeR²OSiMe₃ (R ² = (CH₂)₃NR³CH₂CH(OH)CH₂(OCH₂CH₂) _x OCH₃; R ³ = CH₂(CH₂) _y CH₃; x = 8.4, 12.9, 17.5, 22; y = 2, 6) were synthesized. Their structures were characterized by ¹H NMR and ¹³C NMR. The surface activity and hydrolysis resistant properties of the trisiloxane surfactants prepared were also studied. The values of the critical micelle concentration of all trisiloxane surfactants prepared were at levels of 10⁻⁵ and 10⁻⁴ mol/L. They can reduce the surface tension of water to less than 24 mN/m. The hydrolysis resistant properties of double-tail trisiloxane surfactants are superior to those of single-tail trisiloxane surfactants. The double-tail trisiloxane surfactants 1B (x = 8.4; y = 2) and 2C (x = 12.9; y = 6) can be stable for 8 days in an acidic solution (pH 4.0) and 11 days in an alkaline environment (pH 10.0).     

Influence of Substructures on the Spreading Ability and Hydrolysis Resistance of Double-Tail Trisiloxane Surfactants

Four types of novel double-tail trisiloxane surfactants of the general formula Me₃SiOSiMeR¹OSiMe₃ (R ¹ = –(CH₂)₃NR²CH₂CH(OH)CH₂(OCH₂CH₂)_xOCH₃; R ² = –CH₂CH(OH)CH₂OCH₂(CH₂)_yCH₃, –CH₂(CH₂)₃CH₃, –CH₂CH₂CH(CH₃)₂; x = 8.4, 12.9, 17.5, 22; y = 2, 6), have been synthesized. Their structures were characterized by proton and carbon nuclear magnetic resonance. Most of them are able to reduce the surface tension of water to less than 24 mN/m at concentration levels of 10⁻⁵ mol/L and 10⁻⁴ mol/L. The emphasis was on the influence of substructures on their spreading ability and hydrolysis resistance. The results showed that a weaker hydrophilicity of a surfactant molecule, a larger molar ratio of methyl to methylene in the whole hydrophobic groups, more flexible hydrophobic groups and introduction of a methyl group in the spacer can all improve the spreading ability of the double-tail trisiloxane surfactant solutions on low-energy solid surfaces. The double-tail trisiloxane surfactants 1F and 2F are stable for more than 270 days in a neutral environment (pH 7.0). The hydrolysis resistance of the double-tail trisiloxane surfactants can be improved by a weaker hydrophilicity of the surfactant molecule, and a larger volume of the hydrophobic groups.     

Synthesis and Surface Tension Study of the Spacer Chain Length Effect on the Adsorption and Micellization Properties of a New Kind of Carboxylate Gemini Surfactant

A series of carboxylate gemini surfactants, which contain two hydrocarbon chains linked by amide groups, two carboxylate groups, a flexible alkane spacer were synthesized by three-step reactions and named alkylidene–bis-(N,N′-dodecyl-carboxypropylamides) (2C₁₂H₂₅CnAm; n = 2, 3, 4, 6, 8 is the number of methylene groups of the spacer), their structures were confirmed by FTIR,¹H NMR, and LC–MS/TOF, and their purity checked by HPLC. The micellar properties with increasing spacer chain length of these gemini surfactants were determined by surface tension methods. The critical micelle concentration (CMC) varies slightly with spacer chain length; surface tension at CMC(γ_CMC), the tendency of micellization versus adsorption, CMC/C₂₀, the minimum area per surfactant molecule at the air/solution interface (A_CMC), all decrease with increasing spacer chain length; surface reduction efficiency, pC₂₀, the surface excess at the air/solution interface (Г_CMC) increase with increasing spacer chain length. The results probably indicate that increasing spacer chain length of these carboxylate gemini surfactants will increase spacer incorporation into the double hydrophobic chain.     

Reverse Micellar Encapsulation of d‐ and l‐Enantiomers of Some Aromatic α‐Amino Acids and Nucleobases by Glucose‐Derived Non‐ionic Gemini Surfactants in Neat n‐Hexane

Novel carbohydrate‐based non‐ionic gemini surfactants consisting of two sugar head groups, two hydrophobic tails having chain lengths of C12, C14, and C16 and a flexible –(CH₂)₆– spacer were synthesized and investigated for their reverse micellar encapsulation properties. The head groups of the geminis comprise glucose entities (with reducing function blocked in a cyclic acetal group) connected through C‐6 to tertiary amines. These surfactants were explored for reverse micellar encapsulation of d ‐ and l ‐enantiomers of aromatic α‐amino acids viz. histidine (His), phenylalanine (Phe), tyrosine (Tyr) and tryptophan (Trp) in neat n‐hexane. Similar studies were carried out for encapsulation of nucleobases viz. adenine (Ade), guanine (Gua), thymine (Thy), cytosine (Cyt) and Uracil (Ura). Reverse micellar studies revealed that aromatic α‐amino acids were encapsulated in the sequence His>Tyr>Phe>Trp. In most cases, a difference in the degree of encapsulation of d ‐ and l ‐enantiomers of aromatic amino acids in reverse micellar phases of gemini amphiphiles in neat n‐hexane, was revealed. For Tyr, l ‐enantiomer was better encapsulated than its antipode, i.e., d ‐enantiomer but for Trp, d ‐enantiomer was better encapsulated then l ‐enantiomer. In the case of nucleobases, Ura was found selectively encapsulated by reverse micelles formed by these new amphiphiles.     

Synthesis,Surface and Antimicrobial Activities of Novel Cationic Gemini Surfactants

A series of novel cationic gemini surfactants [C_nH_2n+1–O–CH₂–CH(OH)–CH₂–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? [ 3a (n = 12), 3b (n = 14) and 3c (n = 16)] having a 2‐hydroxy‐1,3‐oxypropylene group [?CH₂–CH(OH)–CH₂–O–] in the hydrophobic chain have been synthesized and characterized. Their water solubility, surface activity, foaming properties, and antibacterial activity have been examined. The critical micelle concentration (CMC) values of the novel cationic gemini surfactants are one to two orders of magnitude smaller than those of the corresponding monomeric surfactants. Furthermore, the novel cationic gemini surfactants have better water solubility and surface activity than the comparable [C_nH_2n+1–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? (n‐4‐n) geminis. The novel cationic gemini surfactants 3a and 3b also exhibit good foaming properties and show good antibacterial and antifungal activities.     

Synthesis and Characterization of Lauryl Trimethyl Ammonium Surfactants with New Counteranion Types

A new family of lauryl trimethyl ammonium surfactants of the general formula CH₃(CH₂)₁₁ N⁺(CH₃)₃X^? (X = CH₃OCOO, HCOO, CH₃COO, CH₃CHOHCOO) were prepared and characterized both structurally and as aqueous surfactants. Lauryl trimethyl ammonium mono-methyl carbonate was synthesized by using dimethyl carbonate (DMC) as the alkylating agent and lauryl dimethyl amine as the starting material. The latter compound was reacted with formic acid, acetic acid, and lactic acid, respectively, to give the corresponding quaternary ammonium salts with other counteranions. They were structurally characterized by IR, ¹H NMR, MS. Members of this family reduced the surface tension of water to 32–38 mN/m at concentration levels of 10^?2 mol/L.     

Synthesis and Solution Properties of Novel Sugar-Based Polysiloxane Surfactants

Two 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 (γ_CMC), 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.     

Reduction of aqueous carbonate photocatalysed by treated semiconductors

Heterogeneous photocatalysed reduction of aqueous Na₂CO₃ solution (1 m) was achieved by using phthalocyanine-coated semiconductor powders (1–3% coating) as well as bare semiconductors. The suspensions were irradiated with 254 nm light from a low-pressure mercury lamp in a nitrogen atmosphere. The phthalocyanine dyes (Fe²⁺-Pc or Co²⁺-Pc) absorb > 80% of the 254 nm radiation and thus sensitize the semiconductor. The products of reduction (CH₃OH and HCHO) were determined spectrophotometrically. The CH₃OH yields obtained are much higher than the HCHO yields, due to a photocatalysed reduction of HCHO to CH₃OH. The CH₃OH yields from coated titania increased linearly with irradiation time over the period 6–18 h. However, the straight line does not pass through the origin, and it seems that a slowing-down occurs at times > 6 h. Titania coated with both dyes gave an optimum CH₃OH yield at 2% surface coating. At higher coating percentages, phthalocyanine screens the surface, thus reducing the light reaching the semiconductor. Changing the redox potential of the phthalocyanine dye by changing its central metal from Fe to Co affects the CH₃OH yields. The bare MoS₂ photocatalyst gave a much higher CH₃OH yield due to the characteristic behaviour of the semiconducting layer-type disulphide, distinguished from that of classical semiconducting materials. In the various semiconductors studied, it seems that there is no correlation between the position of the conduction band and the yield of CH₃OH. Such correlation was argued. Generally, a decrease in the yield of CH₃OH was observed as the band gap width of the semiconductor increased. The yields of the photoproduced CH₃OH generally increased with the percentage of light absorbed at 254 nm by the various semiconductors. Irradiation leads to the production of electrons in the conduction band of the semiconductor. It is likely that the photoproduced electrons reduce CO₃²- initially to HCOO- and then to HCHO and CH₃OH.     

Synthesis and Surface Active Properties of tri[(N‐alkyl‐N‐ethyl‐N‐Sodium carboxymethyl)‐2‐Ammonium bromide ethylene] Amines

Trimeric betaine surfactants tri[(N‐alkyl‐N‐ethyl‐N‐sodium carboxymethyl)‐2‐ammonium bromide ethylene] amines were prepared with raw materials containing tris(2‐aminoethyl) amine, alkyloyl chloride, lithium aluminium hydride, sodium chloroacetate, and bromoethane by alkylation, Hoffman degradation reaction, carboxymethylation and quaternary amination reaction. The chemical structures of the prepared compounds were confirmed by FTIR, ¹H NMR, MS and elemental analysis. With the increasing length of the carbon chain, the values of their critical micelle concentration initially decreased. Surface active properties of these compounds were superior to general carboxylate surfactants C₁₀H₂₁CHN⁺(CH₃)₂COONa. The minimum cross‐sectional area per surfactant molecule (A_min), standard Gibbs free energy adsorption (ΔG_ads) and standard Gibbs free energy micellization (ΔG_mic) are notably influenced by the chain length n, and the trimeric betaine surfactants have greater ability to adsorb at the air/water interface than form micelles in solution. The efficiency of adsorption at the water/air interface (pC₂₀) of these surfactants increased with the increasing length of the alkyl chain. Their foaming properties, wetting ability of a felt chip, and lime‐soap dispersing ability were also investigated.     

Polymerized Surfactant Vesicles

Irradiation of surfactant vesicles prepared from (C₁₈H₃₇)₂ N⁺(CH₃)C₆H₄-CHCH₂p,CT⁻, 1, [C₁₅H₃₁CO₂(CH₂)₂]₂N⁺(CH₃)CH₂C₆H₄CHCH₂,CL⁻ 2, and (C₁₈-H₃₇)₂N⁺(CH₃)CH₂CH₂OCOC₆H₄CHCH₂p,Br⁻, 3, by ultraviolet light or by bursts of 266 nm laser pulses have resulted in the loss of styrene absorbances. This process has been accounted for in terms of a model which considers intravesicular surface reactions to give polymers with average chainlength of 22. Degreees of photopolymerization have been determined in vesicles prepared from 3 subsequent to separating the polystryrene, formed in the photolysis, from the surfactants. Vesicle surface photopolymerizations result in aqueous cleft formation and in enhanced stabilities. Polymerized vesicles provide media for in situ generation of colloidal catalysts and semiconductors.     

Influence of Nature of Spacer and Hydrocarbon Chain Length on Micellar Encapsulation of Polynuclear Aromatic Hydrocarbons by Carbohydrate Derived Non-Ionic Gemini Surfactants in Aqueous Ethanol Medium

Gemini surfactants with rigid aromatic spacer -CH₂-Ar-CH₂-: 6,6′-(N,N′-di(alkyl)-1,4-phenylenedimethylamino)bis(6-deoxy-1,2-O-isopropylidene-α-D-glucofuranose) and Gemini surfactants with flexible aliphatic spacer -(CH₂)₆-: 6,6′-(N,N′-di(2-hydroxyalkyl)-1,6-hexanediamino)bis(6-deoxy-1,2-O-isopropylidene-α-D-glucofuranose) have been synthesized, and their micellar properties for encapsulation of polynuclear aromatic hydrocarbons (PAH) viz. fluorene, anthracene, triptycene, and pyrene in aqueous ethanol medium have been studied by means of electronic spectroscopy. The micellar study reveals that nature of spacer and length of hydrocarbon chain of the surfactant has profound effect on micellar encapsulation of PAH. The surfactants with rigid aromatic spacer show greater encapsulation as compared to surfactants with flexible aliphatic spacer. Moreover, the more hydrophobic surfactant, i.e. the surfactant with a longer hydrocarbon chain, shows greater encapsulation toward PAH which are encapsulated in the order of their smaller size.     

Chitosan–organosilane hybrids—Syntheses,characterization, copper adsorption,and enzyme immobilization

New organic–inorganic hybrids SiGCX (X = 1 to 3) were prepared from the biopolymer chitosan with a degree of the deacetylation of 86% and three distinct silylating agents of the type (CH₃O)₃Si R NH₂ [R =  (CH₂)₃ ,  (CH₂)₃NH(CH₂)₂ and  (CH₂)₃NH(CH₂)₂NH(CH₂)₂ ]. Both chitosan and silylating agents have the amine groups crosslinking through linear glutaraldehyde units. Two stages were proposed for this synthetic method: crosslinking, and sol‐gel processes. The resulting dried hydrogels are amorphous, insoluble in organic as well as acidic or alkaline aqueous media, and exhibited a lamellae‐like surface morphology. The hybrids SiGCX (X = 2 and 3) have a larger adsorption capacity for copper ion than natural chitosan, with very similar kinetics of adsorption, defining a plateau after 1 h. The adsorption of copper increases with the organic chain length of the silylating agents: [(1.72 ± 0.05); (1.98 ± 0.06) and (2.49 ± 0.07)] × 10⁻² mmol/g for SiGCX (X = 1 to 3), respectively, and chitosan adsorbed (1.72 ± 0.05) × 10⁻² mmol/g. These hybrids presented a good capacity for immobilizing enzymes, which decreased with the increase of the organic chain length of the silylating agents, that is, from SiGC3 to SiGC1. The amount of catalase immobilized for the hybrids SIGCX (X = 1 to 3) is 29.03 ± 0.87; 25.79 ± 0.77, and 17.94 ± 0.54 mg g⁻¹, respectively, which is larger than the value of 12.21 ± 0.37 mg g⁻¹ obtained for chitosan. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 797–804, 2000     

Synthesis and thermal properties of poly(urethane)s containing soft and flexible chain as the diols part

Summary α,ω-Diols with long carbon chains, HO(CH₂)₁₂O(CH₂)₁₂OH, HO(CH₂)₁₂O(CH₂)₁₂O(CH₂)₁₂OH, and HO(CH₂)_mOC₆H₄O(CH₂)_mOH (m =6, 12), reacted with diisocyanates to give the corresponding poly(urethane)s in 87–99% yields. Structure of the polyurethane was confirmed by ¹H and ¹³C NMR spectroscopy. IR absorbance due to ν(C=O) vibration of the polymers obtained from hexamethylene diisocyanate was observed at lower wavenumber than that of the polymers from aromatic diisocyanates. Melting point of the poly(urethane)s decreased with increase in flexibility of the polymer chain. Received: 20 April 1998/Revised version: 1 May 1998/Accepted: 22 May 1998     

Synthesis and Surface Activities of Novel Succinic Acid Monofluoroalkyl Sulfonate Surfactants

Two environmentally friendly succinic acid monofluoroalkyl sulfonate surfactants were synthesized from maleic anhydride and polyethylene glycol mono (1H,1H,7H‐dodecafluoroheptyl) ether, i.e. H(CF₂)₆CH₂OCH₂CH₂OCOCH(SO₃Na)CH₂COOH (FEOS‐1) and H(CF₂)₆CH₂(OCH₂CH₂)₃OCOCH(SO₃Na)CH₂COOH (FEOS‐3). The obtained surfactants were characterized by FT‐IR, ¹H NMR, ¹³C NMR and ¹⁹F NMR in detail. The synthesized fluorinated surfactants have a high thermal stability on the basis of thermogravimetric analysis. Their surface properties were examined and the results show that FEOS‐1 and FEOS‐3 surfactants can reduce the surface tension of water to 25.55 mN m^?1 at 10.25 mmol L^?1 and 21.63 mN m^?1 at 8.33 mmol L^?1, respectively; meanwhile, the introduction of oxyethylene groups enhances the hydrophilicity and micellar forming ability and the longer oxyethylene chains the better surface properties. The Krafft points (K_p) of FEOS‐1 and FEOS‐3 were both below 0 °C, which was lower than perfluoro‐n‐heptanesulfonic acid sodium salt (n‐C₇F₁₅SO₃Na, K_p = 56.5 °C) at a similar length of fluorocarbon chains. Comparison studies on two surfactants above and the conventional fluorocarbon surfactants, perfluorooctanoate of ammonium (PFOA) show that the surfactants have comparable properties to PFOA, thus offering an environmentally friendly synthesizing alternatives to PFOA.