EP4347669A1

EP4347669A1 - Multifunctional surfactant

Info

Publication number: EP4347669A1
Application number: EP22732060.3A
Authority: EP
Inventors: Helmut Cölfen; Jonathan Angst
Original assignee: Universitaet Konstanz
Current assignee: Universitaet Konstanz
Priority date: 2021-05-31
Filing date: 2022-05-30
Publication date: 2024-04-10
Also published as: DE102021114054A1; WO2022253767A1

Abstract

The present invention relates to a multifunctional, surface-active comb polymer for compatibilization of at least two phases, and to a process for preparing the multifunctional, surface-active comb polymer according to the invention.

Description

MULTIFUNCTIONAL TENSID

description

The present invention relates to a multifunctional, surface-active comb polymer for compatibilizing at least two phases, and to a process for producing the multifunctional, surface-active comb polymer according to the invention.

Surface-active agents, also known as surfactants, reduce the surface tension between two phases and thus promote the mixing of these phases up to the formation of a dispersion. Surface-active agents are usually made up of two structural units, of which the first structural unit detaches in the first phase and the second structural unit detaches in the second phase. Such surfactants usually consist of a polar structural unit which is soluble in polar solvents (for example water) and a non-polar structural unit which is soluble in non-polar solvents (for example fats and oils). For example, it fulfills the task of emulsifying oil in water.

For more complex tasks such as the stabilization of charged particles, such as mineral nanoparticles, in an aqueous and organic medium, the prior art provides for mixtures of surfactants which, in combination, have the appropriate solubility properties. A disadvantage of these mixtures, however, is the technically complicated formulation, which is required for each specific application. The result is an enormous development effort and associated high development and production costs. Due to the often different storage requirements of the respective surfactants in such mixtures, the associated logistics are also a challenge. In addition, undesired interactions between the different surfactants in the mixture are possible.

There is thus a need for improved, universally replaceable surfactants which circumvent the aforementioned technical and economic problems associated with the use of surfactant mixtures.

Accordingly, the object of the present invention is to provide a multifunctional, surface-active agent which can be used universally for a large number of dispersing tasks.

The object described above is achieved by the embodiments of the present invention characterized in the claims. In particular, a multifunctional, surface-active comb polymer is provided according to the invention, comprising:

(i) at least one polyelectrolyte main chain A,

(ii) at least one side chain B which is bonded to the polyelectrolyte main chain A and which has a solubility of at least 3.3% by weight in a first phase PB, and

(iii) at least one side chain C which is bonded to the polyelectrolyte main chain A and which has a solubility of at least 3.3% by weight in a second phase Pc, with miscibility of the first phase PB and the second phase Pc is 0.3% by weight or less.

The comb polymer according to the invention comprises at least three different functions which are depicted in the respective chains A, B and C (cf. also FIGS. 1a and 1b). The polyelectrolyte main chain A forms the backbone of the comb polymer and has at least partially charged structural units. Due to the corresponding charges of the polyelectrolyte chain, it is able, for example, to bind charged particles such as mineral nanoparticles. The side chains B and C supplement other functions (eg polar, non-polar, fluorophilic, complexing, etc.) which allow the comb polymer according to the invention to stabilize a large number of different phases.

This structure gives the comb polymer according to the invention the ability to recognize the chemical environment and to fold in such a way that the corresponding molecular parts of the comb polymer dissolve in the respective phases and these connect with it. This "intelligent" behavior of the comb polymer according to the invention allows it to be used widely in a wide variety of systems without requiring individual optimization of the surfactant or surfactant mixture.

According to the present invention, the surface-active comb polymer (hereinafter also “the surfactant according to the invention”) comprises at least one polyelectrolyte main chain A. The term “polyelectrolyte main chain” is not particularly restricted here and includes any molecular chain which has a proportion of at least 50 % of electrolyte structural units based on the molar mass of the polyelectrolyte main chain A.

The term “electrolyte structural unit” is to be understood broadly and includes strong and weak electrolytes and any structural units which can carry a negative and/or positive charge in the polyelectrolyte main chain A. In (co)polymers, the electrolyte structural units are, for example, regularly to be equated with the respective repeating units/monomers that can carry a charge (e.g. the respective acrylic acid monomers in a polyacrylic acid used as main chain A).

Examples of such electrolyte structural units include structural units present in anionic form, such as (meth)acrylic acids, sulfonic acids, phosphoric acids or aspartic acid, and structural units present in cationic form, such as ethyleneimine or lysine, without being limited thereto.

The polyelectrolyte main chain A can have up to 50% of the molar mass of non-electrolyte structural units, for example other monomers or non-polymeric chain sections which do not carry any charge and therefore do not contribute to the electrolyte character of the main chain A (cf. FIG. 1b). . The polyelectrolytic character of the polymer backbone A can be controlled and the functionality of the comb polymer according to the invention can be expanded, inter alia, by selecting the type and proportion of such non-electrolyte structural units in the polyelectrolyte main chain A. With proportions of less than 50% of electrolyte structural units in the polyelectrolyte main chain A, a sufficient electrolyte character of the main chain is not guaranteed. Examples of non-electrolyte structural units, which in the Backbone A may be present include but are not limited to acrylamide or vinylpyrrolidone.

Another embodiment includes copolymers of different electrolyte moieties, which may optionally have additional non-electrolyte moieties. For example, according to the present invention, a copolymer can be used as the main chain A, which is made up of acrylic acid and sulfonic acid monomers as two different types of electrolyte structural units. Such a copolymer may be free of non-electrolyte moieties or contain non-electrolyte moieties provided the backbone A comprises at least 50% total electrolytic moieties as defined above.

Examples of the polyelectrolyte main chain A according to the invention include chains which have a proportion of electrolyte units of at least 50%, at least 60%, at least 75%, at least 85% or at least 95%, based in each case on the molar mass of the polyelectrolyte main chain A. A further embodiment of the present invention provides that the polyelectrolyte main chain A consists entirely of electrolyte structural units, ie comprises essentially no other structural elements than those that can carry a charge.

According to the present invention, it is preferred that the polyelectrolyte main chain A is a polymer. Such a polymer can be built up from individual, repeating structural units (monomers), these structural units containing functional groups which can each carry a charge (electrolyte structural units). Here, such a polymer is not particularly limited and includes anionic or cationic polymers.

For example, the polyelectrolyte main chain A can comprise a polymer such as polyacrylic acid, polysulfonic acid or polyphosphoric acid, each of which can be present in anionic form, as well as corresponding copolymers thereof. Alternatively, the polyelectrolyte main chain A can comprise a polymer such as polyethyleneimine, polylysine or polydiallyldimethylammonium chloride (polyDADMAC), each of which can be cationic, as well as corresponding copolymers thereof. A specific example of the present invention relates to a comb polymer wherein the polyelectrolyte backbone A is a polyacrylic acid chain having a plurality of negative charges along the polymer chain through deprotonation of the carboxyl groups. The term "acrylic acid" is not particularly limited here according to the present invention and includes both acrylic acid itself and all acrylic acid derivatives having a free carboxyl group, such as methacrylic acid, itaconic acid, etc., and their salts.

The molar mass of the polyelectrolyte main chain A is not particularly restricted and, depending on the area of application, can be in the range from 0.2 kDa to 1.0 MDa, for example in the range from 1.0 to 800.0 kDa, 1.5 to 500 .0 kDa or 2.0 to 300.0 kDa.

Also, the molecular structure of the polyelectrolyte main chain A is not particularly limited and includes linear, branched and dendrimeric structures. The specific structure of the main chain A can be adapted to the particular polyelectrolyte and the desired application. For example, the main chain A can have a linear structure, since this can ensure advantageous solubility in certain cases.

The comb polymer according to the invention has at least one side chain B and, independently of this, at least one side chain C, which are each bonded to the polyelectrolyte main chain A.

According to the present invention, the side chains B and C are attached to the polyelectrolyte main chain A. The term "bonded to the polyelectrolyte backbone A" is not particularly limited in this regard and includes covalent and non-covalent bonds with both the electrolyte structural units of the main chain A and with the non-electrolyte structural units that may be contained in the main chain A. Typically, the at least one side chain B and the at least one side chain C are covalently bonded to the backbone of the comb polymer according to the invention, ie to individual structural units of the polyelectrolyte main chain A, via a functional group. The side chains can be attached, for example via an ester, amide or imide linkage, to free carboxyl groups present in the respective electrolyte moieties or non-electrolyte moieties. However, it is also conceivable that the side chains B and C are bonded to the main chain A via other functional groups. The at least one side chain B and the at least one side chain C can be bonded to the main chain A via the same functional group or via different functional groups.

The side chains B and C are bonded independently of one another either in a regular or irregular distribution to the structural units of the polyelectrolyte main chain A of the comb polymer according to the invention. For example, side chains B and C are randomly distributed over the length of main chain A.

The side chains B and C that are at least present in the comb polymer according to the invention impart solubility of the multifunctional, surface-active comb polymer in different phases PB and Pc that are immiscible with one another. The side chains B and C are selected in such a way that, depending on the application, they bring about compatibilization of the corresponding phases.

According to the present invention, the side chain B has a solubility of at least 3.3% by weight in a first phase PB and the side chain C has a solubility of at least 3.3% by weight in a second phase Pc.

The expression "solubility of at least 3.3% by weight" refers here to the solubility of a molecule which corresponds to the corresponding unbound side chain B in a phase PB (e.g. a specific solvent). According to the invention, the functional group via which the side chain B is bonded to the polyelectrolyte main chain is not included in the side chain.

To clarify the determination according to the invention of the solubility of the respective side chains, reference is made to example Scheme 1 below. Polyelectrolyte Main Chain A

Determination of the solubility side chain C side chain B Determination of the solubility

Scheme 1

In this example, a polyacrylic acid forms the polyelectrolyte backbone A. One of the carboxyl groups of the backbone A has the side chain B, which is a terminally methylated polyethylene glycol (mPEG), attached via an ester function. In order to determine the solubility of this side chain B in phase PB, a saturated solution of the mPEG side chain supplemented here with a hydrogen atom is prepared in the corresponding phase _PB (here) at room temperature. A known volume of this saturated solution is then removed and the solvent is evaporated. The solubility of the side chain B in the phase P _B in % by weight is determined on the basis of the solids content determined.

This procedure is used analogously to determine the solubility of the at least one side chain C in the second phase Pc, which in Scheme 1 is an example of an octyl group that is bonded to a carboxyl group of the main chain A via an amide function. Here, too, the functional amide group is assigned to the main chain and the terminal CH2 group is supplemented with a hydrogen, so that the solubility measurement is to be carried out with octane.

A similar procedure results for each further optional side chain D, E, F, etc. and the corresponding phases P _D , _PE , P _F , etc., if present. If one of the phases is a solid phase, the above mentioned solubility of the corresponding side chain conceptually replaced by miscibility with this phase.

A solubility of at least 3.3 wt , and the National Formular/, 27th edition", 2009, p.1 to 12). A solubility of side chain B in phase PB of 3.3% by weight therefore relates to a dissolved mass fraction of, for example, 3.3 g of side chain B/100 g of phase PB. The required solubilities are to be determined at a temperature on which the corresponding application is based. This description of solubility values assumes an application temperature that corresponds to room temperature (20°C).

With regard to the above statements, the person skilled in the art is thus directly able to determine the solubility of the side chains in the respective target phase within the framework of the surfactant synthesis and thus to design the multifunctional, surface-active comb polymer according to the invention in accordance with the desired application.

According to a further embodiment, the solubility of the side chains, independently of one another, is at least 4% by weight, at least 5% by weight or at least 8% by weight in the respective phases. Further examples include solubilities of at least 10%, 15%, 20% and 25% by weight.

According to the present invention, the phases P _B and Pc, as well as any other optional phases P _D , _PE , P _F , etc., are essentially immiscible with one another. According to the invention, the solubility or miscibility of the first phase PB and the second phase Pc is 0.3% by weight or less, for example 0.2% by weight, 0.1% by weight or 0.05 or 0 .02% by weight or less. According to the invention, these values also apply to the solubility/miscibility of other optional phases P _D , _PE , P _F , etc. with one another.

The PB phase can be a polar phase (e.g. an aqueous phase) and the phase Pc is a non-polar phase (e.g. hydrocarbons).

Exemplary polar phases include solvents such as water, alcohols, and acids. Specific examples include acetone, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), 1,4-dioxane, 1-methyl-2-pyrrolidine (NMP), glycerol, methanol, ethanol, acetic acid, dimethylacetamide (DMAc) , acetaldehyde/ethanal, (iso)propanol, pyridine, acetonitrile, diethylamine or mixtures thereof.

Exemplary non-polar phases include solvents such as aliphatic and aromatic hydrocarbons and ethers. Specific examples include pentane, hexane, heptane, octane, benzene, toluene, xylene, dimethyl ether, diethyl ether, chloroform, dichloromethane (DCM), or mixtures thereof.

As already stated above, the multifunctional, surface-active comb polymer of the present invention is not limited to the at least one B side chain and the at least one C side chain. In addition to the side chains B and C, the multifunctional, surface-active comb polymer can comprise further side chains D, E, F, etc. which have additional chemical and physical properties which can differ from the polar side chain B and the non-polar side chain C. Analogously to the side chains B and C, these optional side chains D, E, F, etc. have a solubility of at least 3.3% by weight in a corresponding third phase PD, a fourth phase _PE and a fifth phase _PF , etc., on.

Due to the molecular structure defined above, the multifunctional, surface-active comb polymer is suitable for combining several complex solution properties in one molecule.

For example, the comb polymer according to the invention can have a polyelectrolyte main chain A, a polar side chain B, which is approximately soluble in water, a non-polar side chain C, which is approximately soluble in a hydrocarbon, and a perfluorinated side chain D, which is soluble in a fluorinated solvent is soluble. Such a comb polymer according to the invention is, for example, in Able to disperse mineral particles in a 3-phase mixture of water, non-polar solvent and fluorinated solvent.

According to a specific embodiment, the multifunctional, surface-active comb polymer according to the invention therefore comprises, in addition to the side chain B and the side chain C, a further side chain D selected from a fluorophilic or complexing side chain. Examples of such fluorophilic side chains include groups such as perfluorinated C ₆ -C ₁₂₀ alkyl groups, such as perfluorooctyl, perfluorodecyl or perfluorodocecyl groups. Examples of complexing side chains include side chains comprising catechols, pyridine, terpyridine, and other complexing uncharged ligands.

As explained above, the side chains B and C, as well as any optional further side chains, can be bonded to the structural units of the polyelectrolyte main chain A via a functional group. It makes sense here to bind the side chains to the existing functional groups of the electrolyte structural units. For example, side chains B and C can be attached independently to the carboxyl groups of a polyacrylic acid serving as the polyelectrolyte backbone A. Likewise, the side chains B and C can bond to sulfonic acid groups independently of one another, provided that a polysulfonic acid is used as the polyelectrolyte main chain A.

According to this, for example, the carboxyl groups of a polyacrylic acid used as the main chain A are regularly either bound (eg by the side chains B and/or C), as an uncharged carboxyl group or as a free, charged carboxylate group. Likewise, if a polysulfonic acid is used as main chain A, some of the sulfonic acid groups are bound by side chains B and/or C, present as uncharged sulfonic acid groups or as sulfonate anions.

According to the present invention, electrolyte structural units in the main chain A can be charged or uncharged. In order to ensure that the polyelectrolyte main chain A has a sufficient electrolyte character, ie a sufficient number of charges distributed over the main chain, it is necessary that at least a certain proportion of the electrolyte structural units present have a charge. has fertilizer.

According to one embodiment of the multifunctional, surface-active comb polymer defined above, the polyelectrolyte main chain A accordingly comprises a proportion of charged electrolyte structural units of at least 5%, based on the total number of electrolyte structural units in the polyelectrolyte main chain A.

In addition, the proportion of the charged electrolyte structural units is not particularly limited and can be proportions of at least 10%, at least 20%, at least 40%, at least 60%, at least 80% and at least 85%, in each case based on the total number of the electrolyte structural units in the main chain A. If the proportion of charged electrolyte structural units is too low, the polymer backbone A has only a reduced polyelectrolytic character, as a result of which the ability to stabilize charged particles in particular can be insufficient.

The maximum proportion of charged electrolyte structural units in the polyelectrolyte main chain A is not particularly restricted and can be almost 100%, based on the total number of structural units present in the backbone. If a certain proportion of the present side chains B, C or optionally further side chains D, E, F, etc. is bonded to the main chain A via the functional groups of the electrolyte structural units, these groups are generally no longer charged. Therefore, the maximum proportion of charged electrolyte structural units in the polyelectrolyte main chain A is below 100% in such cases, depending on the degree of occupancy of these electrolyte structural units by the corresponding side chains. It is once again made clear that at least one side chain each B and C (and possibly also optional side chains D, E, F, etc.) must be bound to the polyelectrolyte main chain A, but not necessarily to the electrolyte structural units themselves, if so Non-electrolyte structural units are present in the main chain (cf. also Figure 1b).

Examples of upper limits of charged electrolyte structural units therefore include proportions of 99% or less, 95% or less or 90% or less based on the total number of electrolyte structural units present in the main chain A. The present invention only provides that the multifunctional, surface-active comb polymer comprises at least one side chain B and at least one side chain C, each bound to the main chain A. Accordingly, in its simplest form, the present invention comprises a comb polymer having a polyelectrolyte main chain A with only three electrolyte structural units, with a side chain B being bonded to one of the structural units, the side chain C being bonded to a second of the structural units and a third of the structural units is charged.

However, the comb polymer according to the invention can also contain a plurality of side chains B and C, which are each bonded to the main chain A.

According to a further embodiment of the multifunctional, surface-active comb polymer defined above, the proportion of the side chains B in the comb polymer is 0.1 to 80%, based on the total number of electrolyte structural units in the polyelectrolyte main chain A.

The proportion of the side chains B is, for example, 0.1% or more, 0.5% or more, 1.0% or more, 5.0% or more or 10% or more, based on the total number of electrolyte structural units in the Polyelectrolyte Backbone A. Other examples include lower limits of 15%, 20% and 25%.

The proportion of the side chains B is 80% or less, for example 75% or less, 70% or less or 65% or less, based on the total number of electrolyte structural units in the polyelectrolyte main chain A.

According to a further embodiment of the multifunctional, surface-active comb polymer defined above, the proportion of side chains C in the comb polymer is 0.1 to 80%, based on the total number of electrolyte structural units in the polyelectrolyte main chain A.

The proportion of the side chains C is 0.1% or more, 0.5% or more, 1.0% or more, 5.0% or more or 10% or more, based on the total number of electrons lyte structural units in the polyelectrolyte main chain A. More examples close

Lower limits of 15%, 20% and 25%.

The proportion of the side chains C is 80% or less, for example 75% or less, 70% or less or 65% or less, based on the total number of electrolyte structural units in the polyelectrolyte main chain A.

Corresponding ranges as defined above for the side chains B and C also apply to any further side chains D, E, F, etc. which can be contained in the surfactant according to the invention.

As already stated, the distribution of the respective side chains B and C in the comb polymer according to the invention is not particularly restricted and can be distributed regularly or irregularly, for example randomly. The concentration of the side chains in the comb polymer according to the invention can be controlled as a function of the starting stoichiometries.

In a specific exemplary embodiment of the present invention, the polyelectrolyte backbone A consists of a polyacrylic acid, with the side chains B and C being attached to the respective acrylic acid moieties via either an ester or amide bond.

According to one embodiment, the side chain B is selected from the group consisting of polyalkylene glycols and polyvinylpyrrolidones or uncharged water-soluble oligo/polysaccharides such as glucose oligomers. In a preferred embodiment of the comb polymer according to the invention, the at least one side chain B comprises polyethylene glycols whose termini are methylated (mPEG).

According to the present invention, all side chains can be substituted or unsubstituted. The term “substituted” is not particularly restricted here, as long as the respective side chain still has the required solubility in the corresponding phase. For example, the side chains B and C, as well as the optional further side chains D, E, F, etc., can be replaced by alkyl, alkenyl and/or alkynyl groups, by aromatic or heteroaromatic groups, ha logene, carbonyl groups or other functional groups may be substituted.

The molar mass of the side chains B and C, as well as the optional further side chains D, E, F, etc., is not particularly restricted and, depending on the area of application, can be independently in the range from 0.05 kDa to 1.0 MDa lie, for example in the range from 0.1 kDa to 800 kDa, or 0.2 kDa to 500 kDa.

According to a further embodiment of the multifunctional, surface-active comb polymer defined above, the at least one side chain C is selected from the group consisting of C ₆ -C ₁₂₀ linear or branched alkyl groups, C ₆ -C ₁₂₀ linear or branched alkenyl groups, C ₆ -C ₁₂₀ linear or branched alkynyl groups, C ₆ -C ₁₂₀ linear or branched aromatics and C ₆ -C ₁₂₀ linear or branched heteroaromatics. Examples include oligo- and polystyrene derivatives, as well as polyethylene and polybutadiene derivatives, which can be attached to the backbone A via hydroxyl, amino, or acid functions.

According to the present invention, the term "C ₆ -C ₁₂₀ alkyl groups" includes, for example, C ₈ -C _60, C ₁₀ -C ₄₈ or C ₁₂ -C ₃₂ alkyl groups. Specific examples include groups such as hexyl, heptyl, octyl, nonyl, decyl, docecyl, hexadecyl and octadecyl, each of which may be substituted.

According to the present invention, the term "C ₆ -C ₁₂₀ alkenyl groups" includes, for example, C ₈ -C ₆₀ , C ₁₀ -C ₄₈ or C ₁₂ -C ₃₂ alkenyl groups which may contain one or more carbon-carbon double bonds . Specific examples include groups such as hexenyl, heptenyl, octenyl, nonenyl, decenyl, docecenyl, hexadecenyl and octadecenyl, each of which may be substituted. Particularly suitable groups are, for example, 2-decenyl, 9-decenyl, 9-hexadecenyl, 9-octadecenyl, 9,12-octadecadienyl, 6,9,12-octadecatrienyl.

According to the present invention, the term "C ₆ -C ₁₂₀ alkynyl groups" includes, for example, C ₈ -C ₆₀ , C ₁₀ -C ₄₈ or C ₁₂ -C ₃₂ alkynyl groups which may contain one or more carbon-carbon triple bonds . Specific examples include groups such as hexynyl, heptynyl, octynyl, nonynyl, decinyl, docecinyl, hexadecinyl and octadecinyl, each of which may be substituted. A specific example of a suitable group is 6-octadecinyl.

According to the present invention, the term “C ₆ -C ₁₂₀ aromatics” includes, for example, C ₈ -C ₆₀ , C ₁₀ -C ₄₈ or C ₁₂ -C ₃₂ aromatics which contain one or more aromatic groups which may be linked to one another. Examples of such aromatics include groups such as biphenyls, triphenyls and tetraphenyls, but also polystyrenes, which can optionally be substituted.

According to the present invention, the term “C ₆ -C ₁₂₀ heteroaromatics” includes, for example, C ₈ -C ₆₀ , C ₁₀ -C ₄₈ or C ₁₂ -C ₃₂ heteroaromatics which contain one or more heteroaromatic groups which may be linked to one another. Examples of such heteroaromatics include groups such as polypyridinyls, for example bipyridinyl and terpyridinyl, or polyfuranyls, for example bifuranyl and terfuranyl, which may be optionally substituted.

In a preferred embodiment of the present invention, the side chain C comprises a 9-octadecenyl group, as a result of which the multifunctional surfactant has an excellent ability to stabilize in non-polar phases.

In another embodiment, the multifunctional, surface-active comb polymer defined above has a molecular weight of 0.5 kDa to 10.0 MDa.

The molar mass of the comb polymer according to the invention is not particularly restricted and, depending on the field of application, can be in the range from 1.0 kDa to 5.0 MDa or 2.0 kDa to 1.0 MDa. This can be controlled, for example, by the chain length of the polyelectrolyte main chain A and its degree of occupancy with the corresponding side chains B and C, as well as any other optional side chains D, E, F, etc.

If the molar mass is in the range defined above, the comb polymer according to the invention is suitable for a wide range of applications and can fulfill a large number of dispersing tasks. Furthermore, the surfactant according to the invention with a molar mass in this range can have an advantageous solubility in the various various solvents and a reduced tendency to agglomerate.

Another aspect of the present invention relates to a method for producing a multifunctional, surface-active comb polymer, comprising the steps te:

(i) providing a mixture comprising

(i-1) a polyelectrolyte having a molecular weight in the range of 0.2 kDa to 1.0 MDa,

(i-2) a reactant B', comprising a side chain B and a reactive group b bonded thereto, which is suitable for binding the side chain B to the polyelectrolyte main chain A,

(i-3) a reactant C', comprising a side chain C and a reactive group c bonded thereto, which is suitable for binding the side chain C to the polyelectrolyte main chain A,

(ii) heating the mixture from step (i) and optionally

(iii-1) dissolving the product obtained from step (ii) in an aqueous solvent,

(iii-2) adjusting the pH to a value of 5 to 9; and (iii-3) separating the product.

This process allows different types of side chains to be grafted on in a simple manner and thus provides a modular system in which the surfactant properties required in each case can be introduced in a simple manner into the comb polymer according to the invention.

Process step (i) of providing a mixture comprising a polyelectrolyte and the reactants B′ and C′ is not particularly restricted and provides for any order in which the respective starting materials are added. The preparation of the mixture can provide, for example, for the polyacrylic acid to be initially introduced with the reactant B′ and the reactant C′ to be added only afterwards. Alternatively, reactant C' can be added to the polyacrylic acid first and reactant B' only afterwards. Before the addition of reactant C' or reactant B', the mixture of polyelectrolyte and reactant B' or reactant C' can be homogenized, for example by stirring, heating or similar measures. The order in which the respective starting materials are added can be selected with regard to any differences in the reaction kinetics of the reactive groups b and c.

According to a general embodiment of the process according to the invention, a solvent, for example N-methyl-2-pyrrolidone, N,N-dimethylformamide, 1,4-dioxanes, dichloromethane or mixtures thereof, can be added to the mixture during preparation. Furthermore, the mixture can be heated during the preparation. The temperature is not particularly restricted and can be, for example, in the range from 30 to 170.degree. C., from 50 to 150.degree. C. or from 70 to 130.degree. Advantageously, homogeneous mixing can be ensured by adding a solvent and/or heating during the preparation of the mixture.

Reaction step (ii) provides that the mixture provided in step (i) is heated to allow binding of the side chains to the polyelectrolyte main chain A. The mixture is preferably heated to a temperature in the range from 100 to 350.degree. C., for example from 110 to 300.degree. C., or from 120 to 250.degree. The temperature range is dependent on the thermal stability and the boiling points of the respective starting materials (i-1) to (i-3).

According to a further embodiment of the process defined above, the starting materials provided in step (i) have a glass transition temperature of preferably 100° C. or less, for example 95° C. or less or 90° C. or less. If the glass transition temperature of the starting materials from step (i) is in the range defined above, advantageous homogeneous mixing of the starting materials is ensured.

Furthermore, according to the present invention, each of the starting materials provided in step (i) preferably has a boiling point of 350° C. or more, for example 400° C. or more or 450° C. or more. With regard to the boiling point of the starting materials, there is no particular upper limit. However, if the boiling temperature of the starting materials is below 350° C., they can be too volatile under the reaction conditions of the process defined above, which makes it difficult for the preparation process to be carried out in a controlled manner.

According to a further embodiment step (ii) is carried out at a reduced pressure, preferably in the range from 0.1 to 50.0 kPa, for example from 1.0 to 40.0 kPa or 2.0 to 20.0 kPa. The duration of heating the reaction mixture in step (ii) of the method defined above is not particularly limited and is adjusted depending on the reactivity. Preferably, the reaction mixture is heated in step (ii) for 30 minutes to 10 hours, for example for 45 minutes to 8 hours or for 1 to 6 hours.

The reactants B' and C'' include both the side chains B and C to be introduced into the comb polymer of the present invention and the corresponding functional groups b and c which serve to bind to the polyelectrolyte backbone A.

The reactive groups of the reactants B′ and C″ are preferably chosen in such a way that a bond can take place with the functional groups of the electrolyte structural units of the polyelectrolyte backbone (cf. FIG. 1a). Examples of such reactive groups include, in particular, hydroxyl groups, which form an ester bond, for example, with corresponding carboxyl or carboxylate groups, and amino groups, which form corresponding amide bonds. It is also conceivable to use carboxylic acid halides which can form esters or acid anhydrides with the carboxyl or carboxylate groups present. The choice of the reactive groups b and c can be coordinated by the person skilled in the art with regard to the functional groups present in the polyelectrolyte main chain A.

The conversion to ester or amide groups, for example, takes place with the formation of water, which is preferably removed from the reaction mixture by the abovementioned heating step (ii). The duration of the heating can be set to one of the periods mentioned above in order to ensure that the formation of water and thus the conversion of the educts is essentially complete.

According to the present invention, it is also possible to bind the side chains exclusively or additionally to non-electrolyte structural units which may be present in the polyelectrolyte main chain A (cf. FIG. 1b). This procedure offers the possibility of introducing a large number of different binding sites into the main chain and thus also introducing side chains orthogonally to one another.

According to the present invention, the process defined above also envisages introducing other types of side chains (D, E, F, etc.) into the comb polymer according to the invention, for example by known grafting techniques. Analogously to the reactants B' and C', these further side chains can also be present as reactants D'E', F', etc., which comprise correspondingly reactive groups d, e, f, etc., to the reaction mixture in step ( i) are added (i.e. analogously as starting materials (i-4), (i-5), (i-6), etc.).

Alternatively, these additional side chains can be added as reactants D', E', F', etc. after the addition of either or both of reactants B' and C'. In addition, it is conceivable that the additional reactants D', E', F', etc. are added to the final comb polymer containing chains A, B and C, for example after step (ii) of the process according to the invention, in order to Graft side chains D, E and F onto the polyelectrolyte main chain A.

After completion of the heating step (ii) of the process defined above, the multifunctional, surface-active comb polymer formed can be isolated from the reaction mixture by various means known to those skilled in the art.

According to a specific embodiment, the method defined above provides for example a purification step (iii), comprising the steps (iii-1) dissolving the product obtained from step (ii) in an aqueous solvent, (iii-2) adjusting the pH to a value of preferably from 5 to 9, for example from 6 to 8, or from about 7, optionally to precipitate the product, and (iii-3) Separating (of any precipitated) product, such as by ultrafiltration.

The present invention provides a new type of intelligent surface-active agent which, due to its multifunctional structure, is suitable for compatibilizing a large number of different phases. By choosing suitable ketenes, the polymer can recognize the chemical environment and fold in such a way that the best possible bond with the individual phases is ensured (cf. also Figures 2a to 2d.

This novel structure of a multifunctional surfactant enables a large number of applications, including in the cleaning sector and in the cosmetics sector, as well as in the dispersing of nanoparticles or as a rheology optimiser. In addition, the surface-active agent according to the invention can be used for compatibilizing phase-separating solids such as polymers and for dispersing fillers in polymers. As a result, the use of complex mixtures of conventional binary surfactants can be avoided.

The figures show:

1a shows the schematic structure of a multifunctional comb polymer according to the invention based on polyacrylic acid as the main chain, where (O) is the acrylic acid re units, the side chains B and represent the side chains C.

1b shows the schematic structure of a multifunctional comb polymer according to the invention based on polyacrylic acid as the main chain, which has non-acrylic acid units in the main chain, where (O) is the acrylic acid units and the non-acrylic acid units, the side chains B and represent the side chains.

figs 2a-d schematically show the adaptation of the multifunctional, surface-active comb polymer to different phases.

Fig. 3 shows the reaction scheme of a multifunctional, surface-active comb polymer in accordance with the method of preparation of the invention drive.

examples

The following examples serve to illustrate the present invention, but are not limited thereto.

Example 1: Preparation of the multifunctional, surface-active comb polymer: A multifunctional, surface-active comb polymer was made from a polyacrylic acid with a molecular weight of 5 kDa as the polyelectrolyte main chain A, a methoxypolyethylene glycol (mPEG) with a molecular weight of 5 kDa as the polar side chain B and an oleylamine as non-polar side chain C.

For this purpose, the polyacrylic acid (3.6 g, corresponding to 50 mmol repeating units) and the mPEG (6.25/12.5/18.75 g, corresponding to 1.25/2.5/3.75 mmol) were used first crushed with a mortar, mixed and then charged and melted at a temperature in a range of 90 to 110°C. Then the oleylamine (0.33/0.67/1.00 g, corresponding to 1.25/2.5/3.75 mmol) was added by means of a syringe and the mixture was stirred for 5 to 10 min at a temperature in the stirred from 90 to 110°C until the formation of the stable carboxylate salt could be observed.

The mixture was then heated to 175° C. and stirred at a reduced pressure in the range from 0.02 to 0.2 mbar for 3 h. The product was then dissolved in water at a temperature of approx. 90° C., neutralized (precipitated) by adding a saturated aqueous NaHCO ₃ solution to a pH of 7 and then separated off by ultrafiltration. The separated product was freeze-dried.

250 μL of tetrachloroauric acid (HAuCl4) (0.01 M, 3.943 mg/mL) were placed in a 50 mL snap-cap jar. 3 mL of a 5 mg/mL polymer solution containing the polymer obtained from Example 1 were added to the auric acid. In a water bath the mixture was heated to 30°C and stirred for 30 min. A fresh 0.01 M sodium borohydride (NaBH ₄ ) solution was prepared by dissolving 38.7 mg of NaBHU in 100 mL of ice-cold MilliQ. 600 μL of the NaBH ₄ solution were quickly added to the reaction mixture with vigorous stirring, the dispersion turning red. Stirring was continued vigorously for a further minute and the dispersion was then aged at 30° C. for 2 h. The particles were only produced in water, then some of the particles were centrifuged with the addition of HCl (10 min at 9000 rpm) and then taken up in CHCl ₃ . Both the aqueous portion and the portion present in CHCl ₃ were subsequently examined several times using UVA/is spectroscopy (see Table 1).

The stabilizing ability of the multifunctional surfactant was determined by means of UV/Vis spectroscopy via the increase in particle size, as described in P. Zheng, et al., Langmuir, Vol. 22, No. 22 (2006): pp. 9393-9396.

If no increase in size of the particles could be determined over a period of 2 weeks, the stabilizing ability in the corresponding phase or the corresponding phase mixture was rated as "good". If an increase in the size of the particles could be determined within the period of 2 weeks by means of UV/Vis spectroscopy, the stabilization ability in the corresponding phase or the corresponding phase mixture was rated as "poor".

As can be seen from Table 1, gold particles were stabilized by the multifunctional, surface-active comb polymer according to the invention both in water (polar phase) and chloroform (non-polar phase) and in a mixture of water and chloroform (polar and non-polar phase).

Table 1:

"X" = included; = not included

Claims

patent claims

A multifunctional comb polymer surfactant comprising:

(i) at least one polyelectrolyte main chain A,

(ii) at least one side chain B which is attached to the polyelectrolyte main chain A and which has a solubility of at least 3.3% by weight in a first phase PB, and

(iii) at least one side chain C which is attached to the polyelectrolyte main chain A and which has a solubility of at least 3.3% by weight in a second phase Pc, with miscibility of the first phase PB and the second phase Pc is 0.3% by weight or less.

2. The multifunctional, surface-active comb polymer according to claim 1, wherein the polyelectrolyte main chain A comprises a proportion of charged electrolyte structural units of at least 5%, based on the total number of electrolyte structural units in the polyelectrolyte main chain A.

3. Multifunctional surface-active comb polymer according to claim 1 or 2, wherein the proportion of side chains B in the comb polymer is 0.1 to 80% based on the total number of electrolyte structural units in the polyelectrolyte main chain A.

4. Multifunctional, surface-active comb polymer according to any one of claims 1 to 3, wherein the proportion of side chains C in the comb polymer is 0.1 to 80%, based on the total number of electrolyte structural units in the polyelectrolyte main chain A.

5. Multifunctional, surface-active comb polymer according to any one of claims 1 to 4, wherein the polyelectrolyte main chain A is selected from the group consisting of polyacrylic acid, polysulfonic acid, polyphosphoric acid or polyasp- ragic acid, as well as copolymers thereof, or wherein the polyelectrolyte backbone A is selected from the group consisting of polyethyleneimine, polylysine, polyDADMAC or copolymers thereof.

6. Multifunctional, surface-active comb polymer according to any one of claims 1 to 5, wherein the side chains B are selected from the group consisting of polyalkylene glycols and polyvinylpyrrolidones.

7. Multifunctional, surface-active comb polymer according to one of claims 1 to 6, wherein the side chains C are selected from the group consisting of C ₆ - C ₁₂₀ linear or branched alkyl groups, C ₆ -C ₁₂₀ linear or branched Ten alkenyl groups, C ₆ -C ₁₂₀ linear or branched alkynyl groups, C ₆ - C ₁₂₀ linear or branched aromatics and C ₆ -C ₁₂₀ linear or branched heteroaromatics.

8. The multifunctional, surface-active comb polymer according to any one of claims 1 to 7, wherein the polyelectrolyte main chain A comprises polyacrylic acid, and/or wherein the side chain B comprises polyethylene glycol, and/or wherein the side chain C comprises 9-octadecenyl.

9. Multifunctional, surface-active comb polymer according to any one of claims 1 to 8, wherein the comb polymer has a molecular weight of 0.05 kDa to 10 MDa.

10. A process for producing a multifunctional, surface-active comb polymer, comprising the steps:

(i) providing a mixture comprising

(i-1) a polyelectrolyte with a molar mass in the range from 0.2 kDa to 1 MDa,

(i-2) a reactant B' comprising a side chain B and a reactive group b attached thereto, suitable for forming the side chain B to bind to the polyelectrolyte backbone A, and

(i-3) a reactant C' comprising the side chain C and a reactive group c attached thereto which is suitable for connecting the side chain C to the polyelectrolyte backbone A, (ii) heating the mixture from step (i ) and if necessary

(iii-1) dissolving the product obtained from step (ii) in an aqueous solvent,

11. A process for preparing a multifunctional, surface-active comb polymer according to claim 10, wherein each of the starting materials from step (i) has a glass transition temperature of 100°C or less; and/or wherein each of the starting materials from step (i) has a boiling point of 350° C. or more.