RU2030428C1 - Microemulsion - Google Patents

Abstract

FIELD: lubricant materials. SUBSTANCE: microemulsion has water, simple perfluoropolyether with average mol. mass 500-3000 with terminal perfluoroalkyl groups and fluorinated surface-active substance taken at the definite mass ratio. EFFECT: improved quality of microemulsion. 2 cl, 6 tbl

Description

 The invention relates to microperfusions based on a simple perfluoropolyether, which are stable in a certain temperature range, and can be used to obtain lubricants.

 Aqueous microemulsions of perfluorinated compounds are known, which are prepared using nonionic fluorinated surface-active agents, which are selected depending on the temperature range in which the microemulsion must be stable.

, или она солюбилизирована поверхностно-активным агентом.A microemulsion is a liquid substance, transparent or slightly opalescent, in which a liquid which is not miscible with the continuous phase is contained in the form of microdispersed droplets having sizes not exceeding 2000

or it is solubilized by a surface active agent.

 When transferred from the temperature range of their existence, microemulsions tend to separate into two phases, however, when they are again transferred inside the mentioned region, the microemulsion is again formed spontaneously by simple mixing. The aim of the invention is to obtain a homogeneous microemulsion with unlimited stability in a certain temperature range.

 This behavior of the systems is a distinctive feature in comparison with the known systems, which are characterized by kinetic stability, but which are thermodynamically unstable.

The invention relates to microperfusions based on a simple perfluoropolyether, stable in a certain temperature range and consisting of a uniform transparent or opalescent liquid, including:
water
simple perfluoropolyether
a fluorinated surfactant and optionally C ₁ -C ₁₂ alkanol (preferably 1 to 2 carbon atoms) or a fluorinated alcohol, preferably having the structure of a perfluoropolyether or alcohol formed by a partially or fully fluorinated hydrocarbon chain.

 Emulsions may contain additives, for example, water-soluble salts, capable of changing the ionic strength of an aqueous solution.

Microemulsions containing perfluoropolyethers in the form of mixtures of compounds having the same molecular structure but different molecular weights (polydisperse systems) in a wide range of average molecular weights, in the presence of appropriate concentrations of fluorinated surfactants and, possibly, fluorinated alcohols or alkanols with short chains. You can use water-soluble salts such as KNO ₃ , performing the function of increasing the ionic strength of the aqueous phase and changing the interfacial tension between immiscible liquids.

CF₂O)_п(CFO)_m(

O)_pR′f со случайным распределением перфтороксиалкиленовых блоков, где R_f и R'_fмогут быть как одинаковыми, так и различными и являются - CF₃, -C₂F₅, -C₃F₇, a m, n, p имеют такие значения, зависящие от среднего молекулярного веса, 2) RfO(CF₂CF₂O)_n(CF₂O)_mR'f со случайным распределением перфтороксиалкиленовых блоков, где Rf и R'f могут быть как одинаковыми, так и различными и являются - CF₃, или - C₂F₅, a m и n принимают значения, которые зависят от приведенных выше условий; 3) RfO(CF₂CF₂O)_n(CF₂O)

CF₂O

-R′f со случайным распределением перфтороксиалкиленовых блоков, в которой Rf и R'f могут быть как одинаковыми, так и различными и являются - CF₃, - C₂F₅ или - C₃F₇, a m, n, p, принимают такие значения, которые подчиняются приведенным выше условиям; 4) Rf

CF₂O

-R′f где Rf или R'f могут быть как одинаковыми, так и различными и являются - С₂F₅ или - C₃F₇, a n принимает такое значение, которое подчиняется приведенным выше условиям;
5) RfO (CF₂CF₂O)_n R'f, где Rf и R'f могут быть как одинаковыми, так и различными и являются - СF₃, - C₂F₅, a n принимает такое значение, которое подчиняется приведенным выше условиям;
6) RfO (CF₂CF₂CFO)n R'f, где Rf и R'f могут быть как одинаковыми, так и различными и являются - СF₃ или - C₂F₅, или - C₃F₇, n принимает такое значение, которое подчиняется приведенным выше условиям. 7) RfO

O

O

R′f
и
Rf

O

O

O

R′f в которой Rf, R'f являются перфторалкилом, R''f являются F или перфторалкилом, n принимает такое значение, которое подчиняется приведенном выше условию для среднего молекулярного веса.Simple perfluoropolyethers that are suitable for the formation of microemulsions include simple perfluoropolyethers having an average molecular weight of 400-10000, preferably 500-3000, and belonging to one or more of the following classes: 1) RfO (

CF ₂ O) _p (CFO) _m (

O) _p R′f with a random distribution of perfluoroxyalkylene blocks, where R _f and R ' _f can be the same or different and are - CF ₃ , -C ₂ F ₅ , -C ₃ F ₇ , am, n, p have such values depending on the average molecular weight, 2) RfO (CF ₂ CF ₂ O) _n (CF ₂ O) _m R'f with a random distribution of perfluorooxyalkylene blocks, where Rf and R'f can be the same or different and are - CF ₃ , or - C ₂ F ₅ , am and n take values that depend on the above conditions; 3) RfO (CF ₂ CF ₂ O) _n (CF ₂ O)

CF ₂ O

-R′f with a random distribution of perfluoroxyalkylene blocks in which Rf and R'f can be the same or different and are - CF ₃ , - C ₂ F ₅ or - C ₃ F ₇ , am, n, p, take values that obey the above conditions; 4) Rf

CF ₂ O

-R′f where Rf or R'f can be the same or different and are - C ₂ F ₅ or - C ₃ F ₇ , an takes on a value that obeys the above conditions;
5) RfO (CF ₂ CF ₂ O) _n R'f, where Rf and R'f can be the same or different and are - CF ₃ , - C ₂ F ₅ , an takes a value that obeys the above conditions;
6) RfO (CF ₂ CF ₂ CFO) n R'f, where Rf and R'f can be the same or different and are - CF ₃ or - C ₂ F ₅ , or - C ₃ F ₇ , n takes a value that obeys the above conditions. 7) RfO

O

O

R′f
and
Rf

O

O

O

R′f in which Rf, R'f are perfluoroalkyl, R''f are F or perfluoroalkyl, n takes on a value that obeys the above condition for the average molecular weight.

Fluorinated surfactants that make up a microemulsion can be either ionic or non-ionic. In particular:
a) perfluorocarboxylic acids containing from 5 to 11 carbon atoms, and their salts;
b) perfluoro (mono) sulfonic acids containing from 5 to 11 carbon atoms and their salts;
c) nonionic surfactants;
d) mono- and dicarboxylic acids derived from perfluoropolyethers and their salts;
e) nonionic surfactants containing a perfluoropolyether chain linked to a polyoxyalkylene chain;
f) perfluorinated cationic surfactants or surfactants derived from perfluoropolyethers containing 1, 2 or 3 hydrophobic chains.

 Microemulsions have the form of one transparent or opalescent phase, stable in a certain temperature range, depending on the concentration of the structure and the average molecular weight of PFPE (simple perfluoropolyether), on the type and concentration of surfactants and on the possible presence of alcohol and electrolytes.

, в микроэмульсии типа "вода в масле" (в/м), диспергированная фаза образована водной жидкостью (или водным раствором) в форме микродиспергированных частиц, имеющих размеры, которые изменяются в области от 50 до 2000

.An oil-in-water microemulsion (m / v) is represented by a continuous phase — an aqueous liquid (or aqueous solution), and the dispersed phase is formed by a simple perfluoropolyether (PFPE) in the form of microdispersed particles with sizes ranging from 50 to 2000

, in a water-in-oil microemulsion (w / m), the dispersed phase is formed by an aqueous liquid (or aqueous solution) in the form of microdispersed particles having sizes that vary in the range from 50 to 2000

.

 Microemulsions of the first type are obtained when the volume of aqueous liquid in an amount is greater than the volumetric amount of PFPE. When the amount of PFPE prevails relative to the aqueous liquid, the formation of microemulsions of the second type is more likely.

 In both cases, fluorinated alcohols or non-fluorinated alcohols of the aforementioned type can be added to microemulsions, such additives are called joint surfactants.

 In some cases, it is possible to convert microemulsions of the first type into microemulsions of the second type, and vice versa by adding, respectively, PFPE or water to the emulsion and / or by changing the temperature of the emulsion.

The structure and properties of microemulsions containing a simple perfluoropolyether are determined by several parameters, in particular:
type of surfactant and its chemical and physical characteristics;
the molecular weight of the surfactant and its polydispersion;
molecular weight of a simple perfluoropolyether;
type and concentration of joint surfactant;
temperature
electrolyte concentration.

For example, in the case of a surfactant consisting of a carboxylic acid having a perfluoroether structure with an average equivalent weight of 634 in the presence of C ₂ H ₅ OH as co-surfactant with a molar ratio of surfactant: co-surfactant = 0.3, micro perfluoro polyether emulsions can be obtained (PFPE) in water. These microemulsions are of m / v type, as they can be very diluted with water and contain less than 30 wt.% PFPE.

The same surfactant in the presence of alcohol H (CF ₂ ) ₆ CH ₂ OH (as) co-surfactant solubilizes an aqueous solution of HNO ₃ (0.1 M) in PFPE, and a microemulsion of the following composition is obtained: 40 weight% surfactant + co Surfactant 15% of the aqueous phase, 45% PFPE. The resulting microemulsion is of a v / m type. The applicant found that using a more dilute aqueous solution, namely 0.01 M HNO ₃ , it is possible to solubilize a larger amount of the aqueous phase in PFPE.

Example 1. 18 g of acid having the structure of a simple perfluoropolyether class 1 as defined above, having monocarboxylic functionality (R'f = CF ₂ COOH) containing only small amounts of bicarboxylic acid (R'f = Rf = = CF ₂ COOH), consisting of a mixture of components, where m / p = 1, n / p + m = 10, having different molecular weights and with an average equivalent weight of 466, are neutralized with 11 ml of ammonia solution containing 10 wt. % NH ₃ , and diluted to a volume of 50 ml with twice distilled water.

25 ml of the resulting solution is heated in a water bath until the excess NH _{3 is} completely removed: the residue is diluted to a volume of 20 ml with twice distilled water.

To the surfactant solution thus obtained, 1 ml of alcohol having the structure of a class 1 perfluoroether ether (and an average molecular weight of 600, essentially consisting of monoalcohol (R'f = CH ₂ OH) and containing only small amounts of divalent alcohol (R ') is added with vigorous stirring f = Rf = -CH ₂ OH), and then 3 ml of a simple perfluoropolyether belonging to class 1), consisting of a mixture of components having different molecular weights and an average molecular weight of 600. The result is a microemulsion, which is characterized by the following by properties: it is a transparent liquid that is stable at room temperature. A visual check of this system is carried out 2 months after its receipt, while no changes were noted, the above characteristics. When the product is heated to a temperature above 40 - 50 ^{° C,} a perfluoropolyether separated and the product becomes cloudy.

 When cooled to room temperature, the system spontaneously acquires the property of a microemulsion that is stable over time.

PRI me R 2. 18 g of acid having the structure of a simple perfluoropolyether, with the characteristics specified in example 1, and an equivalent weight of 632, is neutralized with 10 ml of an aqueous solution (10%) of ammonia, and then add 20 ml twice distilled water. The solution thus obtained was heated to 70 ° ^C, is added with vigorous stirring, 6 ml of a perfluoropolyether of class 1 with a molecular weight of 800.

The resultant microemulsions were simple perfluoropolyether microemulsions which are stable at temperatures from 60 to 90 ° ^C.

 After cooling the system to room temperature, it is divided into components - water and oil: the simple perfluoropolyether is again solubilized by heating to a temperature of stability; this process proceeds spontaneously.

PRI me R 3. In 0.5 ml of alcohol having the structure of a simple perfluoropolyether class I (Rf = - CH ₂ OH), with an average equivalent weight of 600 add 4 ml of an alkaline acid solution having the structure of a simple perfluoropolyether class 1 with an average equivalent weight 466 obtained in accordance with the description given in example 1. Then add 0.5 ml of twice distilled water, 3 ml of simple perfluoropolyether, class 1), with a molecular weight of 600 and 0.1 ml of a 1 M solution of KNO ₃ .

The composition so obtained consists only of opalescent phase in the range of from 15 to 23 ° ^C. Outside of this temperature range perfluoropolyether and water are separated. PFPE again undergoes solubilization completely spontaneously when the system is again transferred to the temperature range of existence.

 PRI me R 4. In 2 ml of an alkaline surfactant solution having the structure of a simple perfluoropolyether obtained in example 1, add 0.1 ml of alcohol having the structure of a simple perfluoropolyether belonging to class 1 with an average equivalent weight of 600 and 0.2 ml neutral perfluoropolyether class 2 / with an average molecular weight of 700.

 The system has a single transparent phase that is stable at room temperature and consists of a solubilized neutral perfluoropolyether ether.

PRI me R 5. Prepare a solution containing 10 ml of an acid having a structure belonging to class 1 and an average equivalent weight of 690, 10 ml of NH ₃ with a concentration of 10 wt. %, 6 ml of absolute ethanol and 20 ml of twice distilled water. To this solution was added 6 ml of class 1 perfluoropolyether having an average molecular weight of 600. The resulting system consists of a single transparent phase and is stable at room temperature.

 PRI me R 6. Reproduce the system according to example 5 by adding components in the following order: PFPE, acid, water, ammonia, ethanol.

 In this case, a system is also obtained where the perfluoropolyether is solubilized.

 Example 7. In 1.53 g of ammonium salt of bicarboxylic acid with an average equivalent weight of 500 (average molecular weight of 1000) having the structure of a class 2 perfluoropolyether, add 3 ml of twice distilled water and 0.8 ml of absolute ethanol. To the resulting solution, 0.3 ml of perfluoropolyether belonging to class 1 and having an average molecular weight of 600 is added, a transparent composition is obtained which is stable at room temperature in which PFPE is in a solubilized form.

PRI me R 8. 1 ml of the solubilized composition of example 2 is heated to 70 ^about C and diluted with 1 ml of twice distilled water. The resulting perfluoropolyether is solubilized and stable in the composition in the temperature range 40 - 70 ° ^C.

PRI me R 9. 1 ml of the solubilized system of example 2, heated to 70 ^about C and diluted with 2 ml of twice distilled water. Get, as before, a system of solubilized simple perfluoropolyether, stable at a temperature of 35 - 68 ^about C.

 PRI me R 10. Get the solution according to example 5. With vigorous stirring, add to the solution 4 ml of a simple perfluoropolyether belonging to class 1, having an average molecular weight of 800.

 Get a solution consisting of one single transparent phase, stable at room temperature.

 PRI me R 11. Get the solution of example 5. With stirring with a magnetic stirrer, add 2 ml of class 1 perfluoropolyether having an average molecular weight of 1500 to the solution. The result is a solution consisting of one single transparent phase, stable at room temperature . The solubilization of the oil was slow, but it can be accelerated by light heating.

PRI me R 12. The solution is obtained according to example 5. To this solution is added with stirring with a magnetic stirrer 0.5 ml of a simple perfluoropolyether, class 1, having an average molecular weight of 3000. The result is a solution consisting of one single phase, transparent at 50 ^about C. Solubilization of oil was slow.

 PRI me R 13. Receive 2 ml of an alkaline surfactant solution having the structure of a simple perfluoropolyether according to example 1, then 0.1 ml of alcohol having a structure of a simple perfluoropolyether class 1 and an average molecular equivalent weight of 600, and 0, are added to this solution. 2 ml of neutral simple perfluoropolyether class 3 having an average molecular weight of 610. The resulting system consists only of a transparent phase, was stable at room temperature.

PRI me R 14. In 10 ml of a solution of ammonium perfluorooctanoate with a concentration of 360 g / l add 0.5 ml of alcohol having the structure of a simple perfluoropolyether, with an average equivalent weight of 780, 2 ml of a 1 M solution of KNO ₃ and 0.5 ml perfluoropolyether belonging to class 3 /, having an average molecular weight of 610. This system consists of a single phase which is transparent at a temperature of> 32 ° ^C. The system was still stable at temperatures> 85 ° ^C.

Example 15. 1 ml of an acid having a perfluoropolyether class 1 structure (R'f = - CF ₂ COOH) and an average equivalent weight of 694 was neutralized with 1 ml of an aqueous solution of NH ₃ (10 wt.% NH ₃ ), and 0.5 ml of water and 0.25 ml of co-surfactant agent H (CF ₂ ) ₆ CH ₂ OH are added to the mixture. Then 1.4 ml of PFPE average molecular weight 800, having the structure of class 1 are mixed with the resulting mixture, thereby obtaining a microemulsion of type w / o stable at 20-85 ^{° C} having the following composition:
Surfactant + co-surfactant = 35.6 wt.%, Aqueous phase = 23.8 wt.%, PFPE 800 = 40.6 wt.%.

Addition of a further 1.2 ml PFPE 800 gives a microemulsion stable in the range of 25 - 85 ° ^C. When addition of the resulting microemulsion is 0.5 ml of water was prepared microemulsion w / o, stable in the temperature range of 35 - 75 ^o C.

Example 16. 1 ml of a carboxylic acid having the structure of a class 1 perfluoroether (Rf = —COOH) with an average equivalent weight of 570 is used to form a salt with 1.1 ml of an aqueous solution of NH ₃ (10 wt.% NH ₃ ) and add with 3 ml of water. As co-surfactant, 0.5 ml of a class 1 perfluoropolyether derivative alcohol having an average molecular weight of 690 and an end group of Rf ′ = —CH ₂ OH is added. Then add 1 ml of an aqueous 1 molar solution of HNO ₃ . 2 ml of perfluoropolyether ether (PFPE) of class 1 having an average molecular weight of 600, 650, 800 and 900 are added to the resulting mixture. The specific gravity of all used perfluoropolyethers is about 1.8 g / ml. The resulting mixture in all cases has a pH of about 9. Composition in percent can be described as follows.

 Surfactant + co-surfactant = 26.0 wt.%, Water = 39.4 wt.%, Perfluoropolyether = 34.6 wt.%.

The resulting microemulsions have the following stability region:
PFPE Region
(average mol.m.) stability, ^about With
600 36-48 ^about With
650 35-48 ^about With
800 30-43 ^C
900 33-44 ^about With
PRI me R 17. In 5 ml of a simple perfluoropolyether class 1 having an average mol. m 650, add 5.40 g of acid with the structure of a perfluoropolyether having a functional carboxy group (R'f = - CF ₂ COOH) containing only a small amount of bicarboxylic acid (Rf = R'f = -CF ₂ COOH), with an average mol.m. 735, the resulting mixture was used to form salt using 1 ml of an aqueous solution of ammonium hydroxide containing 10 wt.% NH ₃ . Complete dissolution of the aqueous phase in the oil is ensured by heating to 40 ° ^C. Upon cooling to room temperature observed separation into two phases, but by heating again to a temperature above 40 ^{° C,} again spontaneously a microemulsion prepared containing 6.5 wt.% water.

PRI me R 18. In 6.56 g of ammonium salt of a carboxylic acid with a structure of a class 1 perfluoropolyether having an average equivalent weight of 700, add 5 ml of the same perfluoropolyether according to example 17 and 3 ml of water, resulting in one transparent phase, stable above 30 ^° C. Such microemulsions can be diluted with perfluoropolyether to four times the initial volume, resulting in microemulsions that are stable for an unlimited period of time at room temperature.

PRI me R 19. 5 ml of the above perfluoropolyether according to example 17, dissolved in water in the presence of 5.34 g of ammonium salt of a carbon surfactant having a structure of a simple perfluoropolyether according to class 1, having an average equivalent weight of 600. The emulsion is stable at temperatures above 11 ^° C, formed spontaneously.

PRI me R 20. 3.4 ml of a simple perfluoropolyether having an average molecular weight of 600 belonging to class 1, dissolved in 2 ml of water in the presence of 1 ml of a carboxylic acid having a structure of a simple perfluoropolyether of class 1, having an average equivalent weight of 694 and subjected to neutralization using 0.6 ml of an aqueous solution of ammonium hydroxide containing 20 wt.% NH ₃ and 0.4 ml of tertiary. -butyl alcohol. The result is a transparent phase, stable at temperatures below 30 ^about C.

PRI me R 21. 5 ml of a simple perfluoropolyether having an average mol. a weight of 800 belonging to class 1 is dissolved in 1.1 ml of water and a solution of ammonium hydrate containing 10 wt.% NH ₃ in the presence of 2 ml of a carboxylic acid having a perfluoropolyether structure of class 1 with an average equivalent weight of 630. Using simply mixing the components gives a clear liquid, stable at room temperature; when heated above 35 ^about With receive separation into two phases and the product becomes cloudy; when cooled below 35 ^about With the product again turns into the original emulsion, stable for an unlimited period of time. This emulsion, which contains 7.9% water, may be dissolved to a water content of 11.1%, while the area of its existence is reduced to a temperature below 28 ° ^C. The stability region can be extended by adding an alcohol having a molecular weight of 700, obtained from simple perfluoropolyether class 1: in reality, it is enough to add 1.3 wt.% alcohol to obtain a microemulsion that is stable for an unlimited period of time at a temperature below 65 ^about C.

Example 22 In 2 ml of class 1 perfluoropolyether ether having a molecular weight of 800, 1 ml of surfactant having a class 1 perfluoropolyether structure and molecular weight of 690, 1 ml of NH ₃ with a concentration of 10 wt.% Were added. , and 0.1 ml of 1-nonanol. The result is one transparent phase, stable at 0-95 ^about C.

By the subsequent addition of 0.1 ml of water, the following stability region is obtained: 1 - 62 ^° C.

PRI me R 23. A matrix consisting of 5 ml of a simple perfluoropolyether having an average molecular weight of 800, 1.5 ml of a carboxylic acid with a PFPE structure having an average equivalent weight of 636, and 0.5 ml of a solution of ammonium oxide hydrate with the concentration of NH ₃ 10 wt.%, transparent in the entire investigated temperature range (from 15-20 to 90-95 ^about C) and contains 4.0 wt.% the aqueous phase and 74.1 wt.% oil phase. This matrix is capable of reversibly dissolving in water, having the following behavior. The data are given in table 1.

 PRI me R 24. In the matrix of example 23, add 0.2 ml of methyl alcohol. The system is liquid and isotropic (water = 4.0%) in the entire range of studied temperatures; it is capable of reversible microdispersion in water, while having the following behavior. The data are given in table.2.

 PRI me R 25. In the matrix of example 23, add 0.2 ml of ethanol, the result is a system that is liquid and isotropic in the entire temperature range studied and reversibly forms microdispersion in water, having the following behavior. The data are given in table.3. The remaining data are given in tables 4, 5 and 6.

Claims (2)

1. MICROEMULSION, including perfluorocarbon, fluorinated surfactant and water, characterized in that it contains perfluoropolyether with terminal perfluoroalkyl groups with an average molar m as perfluorocarbon. 500 to 3000 having the following structure:

where R _f , R ' _f = CF ₃ , C ₂ F ₅ , C ₃ F ₇ ,
as a fluorinated surfactant, a simple perfluoropolyether with terminal hydroxyl or neutralized carboxyl groups in a weight ratio of fluorinated surfactant: water: perfluoropolyether 0.1 - 0.72: 0.05 - 0.62: 1 or 1 - 2 84: 0.37 - 38.6: 1, respectively.  2. The microemulsion according to claim 1, characterized in that it additionally contains a surface-active substance alkanol containing 1-12-alkyl radical or its fluorinated derivative with a mass ratio of alkanol: perfluoropolyether 0.02 - 0.18: 1 or 0, 26 - 1.1: 1, respectively.

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