WO2025199656A1

WO2025199656A1 - Crosslinked fatty acid viscoelastic surfactants

Info

Publication number: WO2025199656A1
Application number: PCT/CA2025/050452
Authority: WO
Inventors: Japan Trivedi; Viralkumar PATEL
Original assignee: University of Alberta
Current assignee: University of Alberta
Priority date: 2024-03-28
Filing date: 2025-03-28
Publication date: 2025-10-02
Anticipated expiration: 2026-09-28

Abstract

The present disclosure generally relates to dual-crosslinked fatty acid viscoelastic surfactants and their use in various applications, such as cleaning and personal care products, oilfield applications, and textile applications. These surfactants are synthesized by reacting a fatty acid to an alkyl hydroxy acid to be further reacted with a crosslinking agent to form a network of dual-crosslinked surfactant molecules. This results in surfactants with improved stability, solubility, and viscoelastic properties, making them suitable for use in a wide range of applications.

Description

CROSSLINKED FATTY ACID VISCOELASTIC SURFACTANTS

FIELD

[0001] The present invention relates generally to acid-based surfactants, and in particular to dual-crosslinked quaternary ammonium fatty acid viscoelastic surfactants.

BACKGROUND

[0002] Fatty acid surfactants are a class of surfactants that are composed of a hydrophobic tail and a hydrophilic head. The hydrophobic tail is made up of a long-chain fatty acid, typically derived from animal or vegetable oils and fats, while the hydrophilic head is usually a polar group such as an ammonium, carboxylate or sulfate group. Fatty acid surfactants are commonly used in a variety of personal care products, such as soaps, shampoos, and shower gels, as well as in household cleaning products, due to their ability to effectively remove dirt and oil from surfaces. They are also used in industrial applications, including in the formulation of agrochemicals, textiles, and in oilfield working fluids.

[0003] One of the key advantages of fatty acid surfactants is that they are biodegradable, making them more environmentally friendly than many other types of surfactants. They are also relatively inexpensive to produce and have a long shelflife. However, some fatty acid surfactants can be harsh on the skin and may cause irritation, especially in individuals with sensitive skin.

[0004] Gemini surfactants are dimeric structures, composed of two hydrophobic chains and two hydrophilic heads, linked by a spacer at or near the hydrophilic head group. They are generally multifunctional, as they can offer wetting, emulsifying, softening and dispersing, lubricating, and dynamic surface tension reduction properties. Gemini surfactants can be superior to conventional surfactants in characteristic features due to its molecular structure contributing to the formation of worm-like micelles in water, resulting in the ultra-low interfacial tension (IFT) along with excellent viscoelasticity. These properties are a modern solution for all areas that need surfactants, including oilfields, paints, textiles, agricultural chemicals, detergents, and personal care.

[0005] However, one drawback with conventional Gemini surfactants is they are not environmentally friendly. The larger volume of these surfactants disposed into the environment, despite wastewater treatment processes, is a serious burden and threat to the environment.

[0006] There are two major routes to obtain conventional Gemini surfactants: 1) coupling of long chain tertiary amines with dehydrogenated substrates, and

2) substitution of tertiary diamine by alkyl halides.

These reactions occur through SN2 nucleophilic substitution and proceed most quickly in aprotic solvents. The solvent-based route for synthesizing this class of surfactants is environmentally unfriendly, and is expensive.

[0007] There is growing interest in developing alternative fatty acid surfactants that are derived from sustainable and renewable sources, such as plant-based oils, in order to reduce the environmental impact of these types of surfactants, and to develop solvent-free methods of producing Gemini surfactants, which are preferably biodegradable.

SUMMARY OF VARIOUS EMBODIMENTS

[0008] Disclosed herein are dual-crosslinked fatty acid surfactants, which can represent a significant advance in the field of surfactants. By crosslinking both the hydrophobic and hydrophilic groups of the surfactant molecule, dual crosslinked fatty acid surfactants can offer several advantages over single crosslinked and conventional surfactants. In preferred embodiments, these advantages may include improved stability, increased viscosity, improved thermal stability, improved foam stability, and/or improved surfactant properties.

[0009] In preferred embodiments, the fatty acid component is derived or sourced from a natural biological source, such as a vegetable oil.

[0010] Embodiments of dual-crosslinked fatty acid surfactants may be used in a variety of industries, including personal care, cosmetics, and industrial applications such as the oil and gas industry.

[0011] In one aspect, disclosed is a dual-crosslinked fatty acid surfactant comprising two fatty acid hydrophobic chains and two hydrophilic headgroups, which are joined by a first bridge moiety between the hydrophobic chains and a second bridge moiety between the hydrophilic headgroups. In some embodiments, the headgroup comprises a quaternary amine and a polar substituent, such as a hydroxyl, a sulfate group, a sulfonate group, a phosphate group, or a carboxylate group.

[0012] In some embodiments, the hydrophobic chain comprises a secondary amine group, and the first bridge moiety is bonded to the nitrogen atoms. [0013] In one embodiment, the dual-crosslinked fatty acid surfactant is a compound of formula

(I): where R1 and R2 are each independently a saturated or unsaturated alkyl chain, substituted or unsubstituted, having a chain length of between about 10 carbons to about 30 carbons; R’ and R” are each independently H or a C1-C4 alkyl; Bl and B2 are each independently a short bridging moiety comprising 1 to 4 carbon atoms; nl is an integer from 1 to 9, n2 is zero or an integer from 1 to 4, n3 is zero or an integer from 1 to 4; and P is a polar group, such as hydroxyl, sulfate, sulfonate, phosphate or carboxyl. [0014] In preferred embodiments, the surfactant is a compound of formula (II), where R1 and

R2 are as described above:

[0015] In another aspect, disclosed is a method of synthesizing a dual-crosslinked fatty acid surfactant as described herein, comprising the step of dimerizing a fatty acid surfactant compound.

[0016] In another aspect, disclosed is a method of synthesizing a dual-crosslinked fatty acid surfactant as described herein, comprising the steps of:

(a) reacting a bio-oil, such as canola oil, preferably enriched in long chain fatty acids (Cl 8 and longer) with a secondary amine;

(b) reacting with an alkyl hydroxy acid to add a polar headgroup and produce a monomer surfactant having a hydrophilic portion and a hydrophobic portion; (c) dimerizing the monomeric surfactant by introducing the bridge moi eties using a crosslinking glyoxal.

[0017] In some embodiments, a diamine is used in step (a) to produce a quaternary amine in the hydrophilic portion and a secondary amine in hydrophobic portion.

[0018] In some embodiments, the monomer surfactant is a compound of formula (III)

[0019] In some embodiments, the method comprises the steps of: where R is either R1 or R2 are each independently saturated or unsaturated alkyl chains having a chain length of 10 to 26 carbon atoms.

[0020] In another aspect, described herein is a surfactant composition comprising a dualcrosslinked surfactant as described herein. In some embodiments, the composition is selected from the group consisting of: (a) an interfacial tension and surface tension reducing composition, wherein the dual-crosslinked surfactant is present in a concentration from 0.001% to 2.5% by weight; (b) a viscosifier, wherein the dual-crosslinked surfactant is present in a concentration greater than 0.01% by weight;

(c) an emulsifying agent, wherein the dual-crosslinked surfactant is present in a concentration from 0.001% to 0.5% by weight;

(d) a drag reducer host molecule, wherein the dual-crosslinked surfactant is present in a concentration greater than 0.001 % by weight,

(e) a textile surface finish composition, wherein the dual-crosslinked surfactant is present in a concentration from 0.01 % to 1.0 % by weight; and

(f) a coating composition, wherein the dual-crosslinked surfactant is present in a concentration from 0.1 % to 20%, by weight

[0021] In some embodiments, the composition further comprises another surfactant comprising an anionic, cationic, non-ionic, Gemini or zwitterionic surfactant, a polymer, nanoparticles, a corrosion inhibitor, a biocide, or any mixture thereof.

[0022] In some embodiments, a dual crosslinked fatty acid surfactant can be used at elevated temperature and under harsh salinity environment.

[0023] The specific advantages of dual-crosslinked fatty acid surfactants will depend on the type and degree of crosslinking, as well as the nature of the fatty acid surfactant used. While dual crosslinked fatty acid surfactants may also have some limitations, including limited solubility, increased viscosity, reduced foam stability, compatibility issues with certain ingredients, and potential toxicity, these limitations may be balanced in favour of the advantages to be gained.

[0024] Other features and advantages of the present application will become apparent from the following detailed description taken together with the accompanying drawings. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the application, are given by way of illustration only, since various changes and modifications within the spirit and scope of the application will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS [0025] For a better understanding of the various embodiments described herein, and to show more clearly how these various embodiments may be carried into effect, reference will be made, by way of example, to the accompanying drawings which show at least one example embodiment, and which are now described. The drawings are not intended to limit the scope of the teachings described herein. In the drawings, reference to “BioVES” is one embodiment of a dual-crosslinked surfactant, as synthesized as described in Example 2 below.

[0026] FIG. 1 is a plot of the shear rheology of a disclosed surfactant in tap water.

[0027] FIG. 2 is a plot of the shear rheology of a disclosed surfactant in brine.

[0028] FIG. 3 shows the stability of 1000 ppm of a disclosed surfactant against Fe⁺³.

[0029] FIG. 4 is a plot of the friction (drag) reduction %.

[0030] FIG. 5 are images demonstrating that the tested disclosed surfactant does not create strong emulsion and can be separated very easily as shown with 50% water and 50% Permian reservoir oil sample.

[0031] FIG. 6 is a rheology comparison of a disclosed surfactant with other commercial surfactants.

[0032] FIG. 7 is a comparative plot of the friction reduction capabilities of a disclosed surfactant as compared to other industry standard friction reducers.

[0033] FIG. 8 is a comparison of the rheological stability of a disclosed surfactant with other commercial surfactants.

[0034] Further aspects and features of the example embodiments described herein will appear from the following description taken together with the accompanying drawings.

DESCRIPTION OF VARIOUS EMBODIMENTS

I. GENERAL OVERVIEW

[0035] In view of the foregoing, and owing to the increasing demand for Gemini surfactants, there is a demand for new bio-based classes with comparable effectiveness, and preferably greater effectiveness, to conventional Gemini surfactants. Owing to their low toxicity, and biodegradability, bio-based Gemini surfactants can be valuable products from a viewpoint of environmental protection.

[0036] Accordingly, examples herein provide for a new bio-based Gemini viscoelastic surfactant which is a dual crosslinked fatty acid surfactant comprising two fatty acid hydrophobic chains and two hydrophilic headgroups, which are joined by a first linker between the hydrophobic chains and a second linker between the hydrophilic headgroups.

[0037] In one aspect, the surfactant is a compound of formula (I): in which R1 and R2 are each independently a saturated or unsaturated alkyl chain, substituted or unsubstituted, having a chain length of between about 10 carbons to about 30 carbons;

R’ and R” are each independently H or a C1-C4 alkyl;

Bl and B2 are each independently a short bridging moiety comprising 1 to 4 carbon atoms; nl is an integer from 1 to 9, n2 is zero or an integer from 1 to 4, n3 is zero or an integer from 1 to 4; and

P is a polar group, such as hydroxyl, sulfate, sulfonate, phosphate or carboxyl.

[0038] In one embodiment, the surfactant has the structure of compound II, where R1 or R2 are each independently unsaturated, unsubstituted alkyl chains having a chain length of 10 to 26 carbon atoms; R’ and R” are methyl; Bl and B2 are both ethyl; and nl is 3, n2 is zero, n3 is 1, and P is sulfonate:

In preferred embodiments, R1 and R2 are each one of Cl 8, C20, C22 or C24, or mixtures thereof. In some embodiments, a surfactant composition comprises a mixture of different fatty acid components, which variability is introduced by the source of fatty acids used in the synthetic process.

[0039] The dual-crosslinked surfactants disclosed herein can be used in any application where a Gemini viscoelastic surfactant is necessary or desirable. For example, the dual-crosslinked surfactants can be used in oilfield applications, such as a friction reducer (FR) during fracturing, an IFT reducing and wettability alternating agent for enhancing oil recovery, and/or an iron dissolving agent; all using oilfield brine. The dual-crosslinked surfactants can be used as a surface finisher for cellulose fiber processing and production to enhance the tensile strength along with the properties.

[0040] As provided herein, in some embodiments, the dual-crosslinked surfactants comprises a crosslinked fatty acid sulfonate viscoelastic surfactant. At a general level, crosslinking of fatty acid surfactants can provide one or more advantage:

1. Increased stability: Crosslinked fatty acid surfactants can form a three-dimensional network that provides stability to emulsions and suspensions, preventing them from separating.

2. Improved viscosity: Crosslinked fatty acid surfactants can increase the viscosity of solutions, making them more suitable for certain applications. 3. Increased thermal stability: Crosslinked fatty acid surfactants are less sensitive to heat, making them more suitable for use in high-temperature applications.

4. Improved foam stability: Crosslinked fatty acid surfactants can provide better foam stability, making them suitable for use in cosmetic and personal care products.

5. Improved surfactant properties: Crosslinked fatty acid surfactants can have improved surface activity and better wetting properties compared to their non-crosslinked counterparts.

[0041] In preferred embodiments, the dual-crosslinked surfactants is a viscoelastic surfactant that is synthesized without use of solvents, is readily bio-degradable, and/or has desired properties such as low IFT and surface tension (ST) at low dosage, low critical micelle concentration, high viscosity, non-emulsifying with oil, and/or temperature and brine tolerant that are essential for oilfield applications, fiber processing, industrial cleaning, pump/paper processing, and mineral extraction.

[0042] The property of viscoelasticity in general is well known and reference is made to S. Gravsholt, Journal of Coll. And Interface Sci., 57(3), 575 (1976); Hoffmann et al., "Influence of Ionic Surfactants on the Viscoelastic Properties of Zwitterionic Surfactant Solutions", Langmuir, 8, 2140- 2146 (1992); and Hoffmann et al., The Rheological Behaviour of Different Viscoelastic Surfactant Solutions, Tenside Surf. Det., 31, 389-400, 1994. Of the test methods specified by these references to determine whether a liquid possesses viscoelastic properties, one test which has been found to be useful in determining the viscoelasticity of an aqueous solution consists of swirling the solution and visually observing whether the bubbles created by the swirling recoil after the swirling is stopped. Any recoil of the bubbles indicates viscoelasticity. Another useful test is to measure the storage modulus (G¹) and the loss modulus (G") at a given temperature. If G'>G" at some point or over some range of points below about 10 rad/sec, typically between about 0.001 to about 10 rad/sec, more typically between about 0.1 and about 10 rad/sec, at a given temperature and if G'>10'² Pascals, preferably 10’ ¹ Pascals, the fluid is typically considered viscoelastic at that temperature. Rheological measurements such as G' and G" are discussed more fully in "Rheological Measurements", Encyclopedia of Chemical Technology, vol. 21, pp. 347-372, (John Wiley & Sons, Inc., N.Y., N.Y., 1997, 4th ed.). These references are expressly incorporated herein by reference, where permitted.

[0043] Thus, disclosed are dual-crosslinked surfactants, and a solvent-free method of preparation to enhance its use as a drag reducer, oil recovery agent and surface finisher. Optimization of synthesis route to maximize the purity and yield has also been confirmed by using suitable analytical techniques like FTIR, NMR, and HPLC. Determination of shelf life, and stability against various salinity, pH, and temperature conditions were studied. The IFT, ST, and rheological properties were measured using saline brine.

[0044] Some preferred embodiments of the dual-crosslinked surfactants can have advantages compared to the conventional surfactants (including other Gemini surfactants) as it demonstrated higher viscoelasticity along with ultra-low IFT at low concentrations. In addition, it also showed stability against a considerable amount of Fe⁺³, and a range of alkaline pH even at elevated temperature combinations. Diluted solutions of the dual-crosslinked surfactants were able to stabilize the iron sulfide (FeS) in the dispersion form. One example was tested as a FR during the flow in pipe at high Reynolds numbers using industrial flow loop for the application of hydraulic fracturing of oil and gas reservoirs. The results showed that a diluted solution of 2 gallons per ton (gpt) in tap water can reduce drag by up to 70% in the turbulent flow regime.

[0045] One example has been tested for fiber processing and manufacturing. At the predefined oil pick up values, the dual-crosslinked surfactant showed an excellent tensile properties improvement on the Lyocell cellulose fibers. Also, as an effective surface finish, it helps to reduce the fibrillation of fibers. The concerned measured values for the quality improvement of cellulose fibers were -7-10% higher than the one used in industry. Similarly, the application can be expanded to the hemp and/or jute bast fiber manufacturing.

II. EXAMPLE REACTION TO MANUFACTURE SURFACTANT

[0046] In at least one example, bio-oils, preferably those enriched in long tail fatty acids (C 18- C24), were used as a feed stock for making embodiments of the dual-crosslinked surfactants. As shown in the synthetic schemes below, a solvent-free reaction was carried out. In some examples, this reaction is carried out in a single pot using non-toxic, and non-hazardous reactants in the presence of air. The formation of byproducts after each stage of reaction was minimized to avoid after stage discharge and purification. The optimal operating temperature was tuned between 90°C to 160°C combining a pressure range of 1 to 4 bar.

[0047] A general scheme to synthesize a dual-crosslinked surfactant is as follows: Ri Ri

I’ c =o

= c =o

I ⁰ c

Secondary

Secondary Amine > S

Amine Secondary econdary Alkyl hydroxy I A Amine pH Control

A bio-oil, such as canola oil, preferably enriched in long chain fatty acids (Cl 8 and longer) is combined with a secondary amine, and then reacted with an alkyl hydroxy acid to add the polar headgroup. The monomeric surfactant molecules are then dimerized by introducing the bridge moi eties using a crosslinker such as glyoxal.

[0048] In at least one example, the reaction uses a diamine to produce a quaternary amine in the hydrophilic portion and a secondary amine in hydrophobic portion. One example is as follows: where R is Cl 8, C20, C22 or C24, or mixtures thereof.

III. EXAMPLE RESULTS

(i.) General Results.

[0049] Embodiments of the dual-crosslinked surfactant showed excellent solubility in tap water, brine, and alkaline water. The test results described below were obtained using the dualcrosslinked surfactant obtained in Example 2 below.

[0050] The main results were:

1. The yield of bio-oil to the dual-crosslinked surfactant was more than 95% with the purity of 98%.

2. The shear rheological behavior (FIG. 1) along with the ST and IFT results (Table 1) confirm that the synthesized dual-crosslinked surfactant shows the viscoelastic properties, and high surface activity. The IFT measurements were conducted using a spinning drop method to measure interfacial tension at an elongated drop in a rotating capillary. These unique properties eliminate the compatibility issues of a combined use of polymers and surfactants for enhanced oil recovery. Also, these properties withstand brine and temperature conditions without dual-crosslinked surfactant precipitation. Therefore, dual-crosslinked surfactant can be used under harsh reservoir conditions.

Table 1: IFT with reservoir oil

3. The tested stability of dual-crosslinked surfactant against Fe⁺³ (FIG. 2) up to 1000 ppm may expand its usage as a scale and corrosion inhibitors.

4. The concentration of 2 gpt of dual-crosslinked surfactant reduces the drag of aqueous flow by -70% (FIG. 3). Therefore, dual-crosslinked surfactant has an efficiency to reduce pump power to save industrial operational cost. 5. As shown in FIG. 5, the tested dual-crosslinked surfactant does not create strong emulsion and can be separated very easily as shown with 50% water and 50% Permian reservoir oil sample. Non-emulsification is an important property to be used for production enhancement chemicals.

6. The quality of cellulose fibers (in terms of tensile strength, and fibrillation) improved (Table 2) by 5-10% more compared to the competitor’s product.

Table 2: Dual-crosslinked surfactant as a surface finisher in cellulose fiber industries

7. Surface tension measured by ring method: Compound (III): 38 mN/m & Compound (II): 29 mN/m

(ii.) Fiber Testing Results For Fibers Surface Treated with BioVES Surfactant.

[0051] Tests were conducted to determine the dry tenacity and percent elongation, WAN number and an oil-pick up values.

[0052] Dry Tenacity and % Elongation: Prior to a test, the appropriate pretension weight has to be selected and set on the instrument. Thereafter, a fiber with the corresponding pretension weight is loaded into the instrument. By pressing the operation button shortly, the measurement is initiated - the fiber is set into its natural vibration by an electronic delta impulse. The titer is derived from the fiber‘s vibration frequency. The automatic measurement assures easiest handling, minimum influence of the operator and therewith best accuracy and repeatability. The sophisticated evaluation software allows to generate the results report in either dtex, denier or both values. Combined with Vibrodyn 500, a complete results report with titer, elongation and individual tenacity (tension at break based on the individual fiber titer) is created. [0053] WAN number: Up to 20 single fibers are fixed with a defined angle and a pretension weight over a shaft. During the measurement, the shaft rotates at constant speed and at the same time, it is being permanently moistened. The wet abrasion level is determined by the number of revolutions, with which the fiber tears. The measured values are statistically evaluated and displayed in the software. Since the measured values are titer dependent, it is necessary to consider the titer to get an exact result. If not, the target titer is considered.

[0054] Table 3 shows the fiber testing results:

Table 3 - Fiber Testing Results

[0055] As shown, the finishing agent or surfactant seems very efficient to reduce fiber to fiber and fiber (SV 9.1 cm) to metal frictions (SV 10.5 cm).

[0056] (Hi.) Comparative Results.

[0057] Table 4 provides a comparison of the interfacial tension of the surfactant used with Permian crude oil, as between the disclosed dual-crosslinked surfactant and other competing surfactants. As shown, the dual-crosslinked surfactant reduced surface tension below 30, and interfacial tension around 0.5. The concentration can be adjusted to increase the performance of the dual-crosslinked surfactant.

Table 4 - Comparison of interfacial tension of various surfactants with Permian crude oil

[0058] FIG. 6 shows a rheology comparison of the dual-crosslinked surfactant (shown in the drawings as “BioSurfUA”), as compared to the Ecoslick™ A350 and FR 5390™ (Kemira) surfactants, which are the most prominent friction reducers used for unconventional hydraulic fracturing.

[0059] FIG. 7 shows a comparative plot of the friction reduction capabilities of the disclosed dual-crosslinked surfactant (shown as “UABioSurf ’) as compared to other industry standard friction reducers. As shown, the disclosed surfactant has shown comparable results with industry standard friction reducer, with: (higher than 60% friction reduction when used at 45% concentration. The concentration can be increased to reduce dosage and improve performance.

[0060] FIG. 8 is a comparison of rheological stability of surfactants. FLOP AM™ 3630 (from SNF) is the most prominent polymer used for enhanced oil recovery

IV. EXAMPLES

(i.) Example 1:

[0061] 15.86 g Oleic acid, 15.65 g N, N-dimethyl-1, 3 -propanediamine, 0.20 g Sodium as a catalyst were added to a flask. The reaction mixture was refluxed at 120-160 °C at 2 atmosphere for 14 h. The excess of N, N-dimethyl-1, 3 -propanediamine was removed, and dried product was obtained. 10.46 g Step 1 product, 3.66 g 2-Chloro-2-hydroxy-l -propanesulfonic acid, few drops of ethyl acetate were added to a flask. The reaction mixture was refluxed at about 60-80 °C for 14 hours, the final product was washed, and dried.7.59 g Step 2 product cross-linked with 7 ml Glyoxal under alkaline environment at 40-50 °C for 1 hrs. The precipitates washed, and dried for 20 hours. The product is a viscous solution of dual-crosslinked surfactant. (ii) Example 2:

[0062] 326 g erucic acid and 106 grams of N, N-dimethyl-1, 3 -propanediamine were added to the reaction vessel along with the iron catalyst and kept for 6-8 hours at 60-80°C while stirring at 3.5- 4 atm pressure. The residue was 420g of dark-yellow waxy desired product. 29.6 g Step 1 amide product, 8.55 g 2-Chloro-2-hydroxy-l -propanesulfonic acid, few drops of ethyl acetate were added to a beaker and covered with a lid. The reaction mixture was stirred at 40-50 °C temperature and 1.5 atm pressure for 7 days, a yellow precipitate was dried. 7.5 g (0.0138 m) glyoxal, Step 2 product in a beaker was reacted while controlling about to a neutral pH at 20-35 °C at atmosphere pressure. The final product is a viscous solution of dual-crosslinked surfactant.

(Hi) Example 3:

[0063] 17 grams of Fatty Acid mixture (C18, C20, C22) was mixed with 20.4 grams of N, N- dimethyl-1, 3 -propanediamine at 90-120°C for 21 hours in the presence of 0.1 grams Sodium and iron catalyst under 2 atm pressure. The precipitates then obtained and dried at 80 °C for 24 hours. 10.2 grams of Step 1 precipitates were reacted with 20 grams of 2-Chloro-2-hydroxy-l -propanesulfonic acid for 17 hours at 60-90 C. The precipitate were washed, and dried. 5 grams of sulfonated Fatty Amide was crosslinked with 7 ml of glyoxal at 40- 60 °C for 4-9 hours at about a neutral pH. The precipitates for crosslinked sulfonated Fatty Amide were washed, filtered and dried for 24 hours.

V. INTERPRETATION

[0064] Various systems or methods have been described to provide an example of an embodiment of the claimed subject matter. No embodiment described limits any claimed subject matter and any claimed subject matter may cover methods or systems that differ from those described below. The claimed subject matter is not limited to systems or methods having all of the features of any one system or method described below or to features common to multiple or all of the apparatuses or methods described below. It is possible that a system or method described is not an embodiment that is recited in any claimed subject matter. Any subject matter disclosed in a system or method described that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicants, inventors or owners do not intend to abandon, disclaim or dedicate to the public any such subject matter by its disclosure in this document.

[0065] Furthermore, it will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Also, the description is not to be considered as limiting the scope of the embodiments described herein.

[0066] It should also be noted that the terms “coupled” or “coupling” as used herein can have several different meanings depending in the context in which these terms are used. For example, the terms coupled or coupling may be used to indicate that an element or device can electrically, optically, or wirelessly send data to another element or device as well as receive data from another element or device. As used herein, two or more components are said to be “coupled”, or “connected” where the parts are joined or operate together either directly or indirectly (i.e., through one or more intermediate components), so long as a link occurs. As used herein and in the claims, two or more parts are said to be “directly coupled”, or “directly connected”, where the parts are joined or operate together without intervening intermediate components.

[0067] It should be noted that terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree may also be construed as including a deviation of the modified term if this deviation would not negate the meaning of the term it modifies.

[0068] Furthermore, any recitation of numerical ranges by endpoints herein includes all numbers and fractions subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, and 5) including the endpoints themselves. It is also to be understood that all numbers and fractions thereof are presumed to be modified by the term "about" which means a variation of up to a certain amount of the number to which reference is being made if the end result is not significantly changed. [0069] The present invention has been described here by way of example only, while numerous specific details are set forth herein in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that these embodiments may, in some cases, be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the description of the embodiments. Various modification and variations may be made to these exemplary embodiments without departing from the spirit and scope of the invention, which is limited only by the appended claims.

Claims

1. A dual crosslinked fatty acid surfactant comprising two fatty acid hydrophobic chains and two hydrophilic headgroups, which are joined by a first linker between the hydrophobic chains and a second linker between the hydrophilic headgroups.

2. The surfactant of claim 1 wherein the headgroup comprises a quaternary amine and a polar substituent.

3. The surfactant of claim 2, wherein the polar substituent is a hydroxyl, a sulfate group, a sulfonate group, a phosphate group, or a carboxylate group.

4. The surfactant of any one of claims 1-3 wherein the hydrophobic chain comprises a tertiary amine group, and the first linker bridges between the nitrogen atoms.

5. A dual crosslinked fatty acid surfactant having the structure of compound (I): where R1 and R2 are each independently a saturated or unsaturated alkyl chain, substituted or urlsubstituted, having a chain length of between about 10 carbons to about 30 carbons; Bl and B2 are each independently a bridging moeity comprising 1 to 4 carbon atoms; nl is an integer from 1 to 9, n2 is zero or an integer from 1 to 4, n3 is zero or an integer from 1 to 4; and P is a polar group.

6. The surfactant of claim 5 wherein the polar group comprises a hydroxyl, a sulfate group, a sulfonate group, a phosphate group, or a carboxylate group.

6. The surfactant of claim 5 which is compound II where R1 and R2 are each independently saturated or unsaturated alkyl chains having a chain length of 10 to 26 carbon atoms.

7. The surfactant of claim 6 wherein R1 and R2 are each Cl 8, C20, C22 or C24, or mixtures thereof.

8. A method of synthesizing a dual-crosslinked fatty acid surfactant as claimed in claim 1, comprising the step of dimerizing a fatty acid surfactant compound.

9. A method of synthesizing a dual-crosslinked fatty acid surfactant as claimed in claim 1, comprising the steps of:

(a) reacting a bio-oil, such as canola oil, preferably enriched in long chain fatty acids (Cl 8 and longer) with a secondary amine; (b) reacting with an alkyl hydroxy acid to add a polar headgroup and produce a monomer surfactant having a hydrophilic portion and a hydrophobic portion;

(c) dimerizing the monomeric surfactant by introducing the bridge moieties using a crosslinking glyoxal

10. The method of claim 9 wherein a diamine is used in step (a) to produce a quaternary amine in the hydrophilic portion and a secondary amine in hydrophobic portion

11. The method of claim 9 or 10 in which the monomer surfactant is

12. The method of claim 11 which comprises the steps of: where R is either R1 or R2 are each independently saturated or unsaturated alkyl chains having a chain length of 10 to 26 carbon atoms.

13. A surfactant composition comprising a dual-crosslinked surfactant of any one of claims 1-7.

14. The surfactant composition of claim 13 which is selected from the group consisting of: (g) an interfacial tension and surface tension reducing composition, wherein the dual-crosslinked surfactant is present in a concentration from 0.001% to 2.5% by weight;

(h) a viscosifier, wherein the dual-crosslinked surfactant is present in a concentration greater than 0.01% by weight; (i) an emulsifying agent, wherein the dual-crosslinked surfactant is present in a concentration from 0.001% to 0.5% by weight;

(j) a drag reducer host molecule, wherein the dual-crosslinked surfactant is present in a concentration greater than 0.001 % by weight,

(k) a textile surface finish composition, wherein the dual-crosslinked surfactant is present in a concentration from 0.01 % to 1.0 % by weight; and

(l) a coating composition, wherein the dual-crosslinked surfactant is present in a concentration from 0.1 % to 20%, by weight

15. The surfactant composition of claim 13 or 14, further comprising another surfactant comprising an anionic, cationic, non-ionic, Gemini or zwitterionic surfactant, a polymer, nanoparticles, a corrosion inhibitor, a biocide, or any mixture thereof.