DE3830325A1 - Polyamide and film comprising at least one monomolecular layer of a polyamide - Google Patents

Abstract

A polyamide of the formula <IMAGE> in which Y is a divalent radical, X is a divalent radical having a chain of at least two carbon atoms, A and B, independently of one another, are H or C1-C26-alkyl, and n is an integer greater than 4, contains at least one C6-C16-alkyl group per recurring unit. X and/or Y contain at least one CH2 group in the chain. The polyamide is prepared by reacting a diamine of the formula NHA-X-NHB with approximately equimolar amounts of an activated derivative of a dicarboxylic acid COOH-Y-COOH. The polyamide is suitable for the preparation of ordered monomolecular LB films on a carrier. To this end, it is dissolved in a volatile, organic, water-immiscible solvent, the solution is spread on the water/air interface, and the layer is compressed after evaporation of the solvent and transferred onto a solid layer carrier by the Langmuir-Blodgett technique.

Description

The invention relates to special polyamides Alkyl side chains, on a film of at least one monomolecular layer of these polyamides on a solid Layer support (= so-called layer elements) and method for the production of the polyamides and the layer elements.

For the production of ordered layers of organic Polymer with long-chain side groups is predominant uses the Langmuir-Blodgett (LB) method. With this Processes are molecules on a water surface spread and by reducing the area per molecule the long alkyl side chains arranged in parallel. At The molecules are given constant thrust by input and Dipping onto a substrate. Per dive thereby a monomolecular layer while maintaining its order transfer.

Amphiphiles are used to build LB films Molecules, d. H. Molecules that have a hydrophilic end (one "Head") and have a hydrophobic end (a "tail"). In order to achieve a higher stability of the LB films, polymeric LB films have already been produced.

For this purpose, monomeric unsaturated amphiphiles were once found polymerized during the production of the film. But you also have organic polymers with long Alkyl side chains used for layer production (EP-A2 02 32 829). Occur in both types of polymeric films however, more defects than with monomeric films. At The polymerization in the layer occurs in almost all of them Cases of a contraction of the layer with the training  of imperfections. For films made of polymers, the high Viscosity of the films to problems with the Shift transfer.

The task therefore consisted of low molecular weight Starting products to win polycondensates can be transferred particularly well to the substrate.

The present invention solves this problem. It is based on the observation that components without any CH₂ group in the main chain leads to stiff polymers that are not or only poorly and without order in the film to let.

It has now been found that the polyamide general formula (I)

in which
Y is a divalent residue,
X is a divalent organic radical, the chain of which contains at least two carbon atoms,
A and B, independently of one another, H or C₁-C₂₆-alkyl and
n is an integer over 4,
which has at least one alkyl group C₆-C₁₆, in particular C₁₄-C₂₀, per repeating unit and wherein X and / or Y contain at least one CH₂ group in the chain, ordered layers, z. B. using the Langmuir-Blodgett technique on a solid substrate.

The polyamides used are strictly alternating Dicarboxylic acid and diamine units built. The  different order tendencies of polymer main chain (Tendency to polymer balls) and alkyl side chain (tendency for crystallization) can be realized simultaneously will. IR spectroscopic studies have shown that by introducing at least one CH₂ group in the Main chain of the polymer loses its rigidity and the transferred film gains order. This is a Advantage over the very rigid connections 76 and 77 according to EP 02 32 829.

Y in the chain is preferably free of nitrogen. For example, Y can represent the radical (CH₂) _a , where a is an integer from 0 to 10. The group Y can also represent the radical (CH₂-O-CH₂) _b , where b is a number from 1 to 13. Y can preferably also be an unsubstituted or substituted aromatic group, for example an unsubstituted or substituted phenylene or naphthylene radical.

Because of the easier accessibility of the amines and because easier to obtain uniform end products, it is advantageous if A = B.

It is also preferred if the radical X in the chain is free is of nitrogen. For example, X can be the general one formula

(CH₂) _c -X¹- (CH₂) _c

have, where c is 0, 1 or 2 and X¹ is a substituted or unsubstituted aromatic group. X can in particular mean a substituted or unsubstituted aromatic group.

If the radicals A and B are hydrogen and the groups X and / or Y contain a substituted aromatic group or consist of a substituted aromatic group, this aromatic group can be substituted by at least one of the following:

• - COOH,
  - CO₂-alkyl, the alkyl group containing 1 to 24 carbon atoms,
  Alkyl with 4 to 24 carbon atoms,
  O-alkyl, where the alkyl group contains 14 to 24 carbon atoms,
  - N (alkyl) ₂, the alkyl groups each containing 10 to 24, in particular 14 to 22, carbon atoms,
  - CO-NR⁴R⁵, where R⁴ and R⁵ independently of one another are hydrogen or alkyl radicals having 1 to 24 carbon atoms.

Is particularly preferred as a substituted aromatic radical in this context a 1-substituted 3,5 linked phenylene group.

If one of the radicals A, B is an alkyl group C₁-C₃, the is other hydrogen or an alkyl group C₁-C₃, aromatic groups can also pass through these residues be substituted.

If at least one of the residues A and / or B is a branched one or unbranched alkyl radical having 4 to 24 carbon atoms and at least one of groups X or Y is one contains substituted aromatic radical or from a substituted aromatic radical, so the aromatic group can be substituted by one of the following leftovers:

• - OR²,
  - CH₂OR²,
  - SO₃R²,
  - CONHR²,
  - CONR²R³,

where R² and R³ are independently hydrogen, C₁-C₄-alkyl or C₂-C₄-hydroxyalkyl.  

The polyamides described can be prepared by that you have a diamine of the formula

NHA-X-NHB

with approximately equimolar amounts of a dicarboxylic acid COOH-Y-COOH or an activated derivative of this Reacts dicarboxylic acid, wherein A, B, X and Y the above have the meaning described. Capitalized derivatives of the dicarboxylic acids are, for example, the acid chlorides, the thiophenyl esters or other activated esters. For example, one can use diamines of the formula

R¹-NH-X-NH-R¹,

where R¹ is an alkyl group with 4 to 24, preferably means 14 to 22 carbon atoms, with about equimolar amounts of a dicarboxylic acid dichloride general formula

ClOC-R³-COCl

implement, where R³ for a polymethylene chain with 0 to 10 carbon atoms.

Examples of dicarboxylic acids that can be used can be found in Table 1, examples of diamines which can be used in Table 2, Examples of polyamides produced in Table 3 The polyamides according to Table 4 are the same producible.

For the polycondensation instead of a diamine or a diacid dichloride also mixtures of diamines or Diacid dichlorides are used.

To produce the films according to the invention, the organic polycondensates in a volatile solvent dissolved and on the surface of an aqueous solution in a Brought film scale (spread). From the dimension of the Surface, the spreading volume and the concentration of the The solution is the average area per repeating unit calculated. Phase transitions in the compression of the molecules can be traced in the shear surface isotherm.  

The molecules are pushed together with a barrier, the alkyl chains with increasing surface density in be oriented essentially perpendicular to the boundary layer. Self-organization occurs during compression the molecules at the interface are a monomolecular film, whose constant layer thickness through the chain length of the Molecules and their tilt angle (this is the angle at which the molecular chains on the water surface against the Normal are tilted) is determined. The typical thickness such a film is around 2-3 nm.

The film is at constant thrust by immersion or Immersion of a suitable carrier while maintaining order removed from the water surface.

Water is usually used as the subphase for monofilm production or aqueous solutions. But there are also others Liquids with high surface tension, such as B. Glycerin, glycol, dimethyl sulfoxide, dimethylformamide or Acetonitrile can be used insofar as the polyamides are found in these Do not dissolve liquids.

Any solid, preferably Dimensionally stable substrates from different Materials into consideration. Those serving as layer supports For example, substrates can be transparent or translucent, electrically conductive or insulating. The substrate can be hydrophobic or hydrophilic. The Surface of the substrate to which the LB layer is applied can be hydrophobic. The one to be coated Surface of the substrate should be as clean as possible, so the formation of a thin, orderly layer is not is disturbed. In particular the presence of surfactants on the surface to be coated The surface of the substrates can be layered affect. It is possible to use it as a base  serving substrates on the surface to be coated the application of the LB films with a first Intermediate layer to provide z. B. the liability of the film to improve on the substrate.

As materials for the substrates, for example Metals such as gold, platinum, nickel, palladium, Aluminum, chrome, niobium, tantalum, titanium, steel and the like be used. Other suitable materials for the Substrates are plastics, such as polyester, such as polyethylene terephthalate or polybutylene terephthalate, Polyvinyl chloride, polyvinylidene chloride, Polytetrafluoroethylene, polystyrene, polyethylene or Polypropylene.

Semiconductors such as silicon Germanium or gallium arsenide or glass, Silicon dioxide, ceramic materials or cellulose products considered for the substrates. The surface of glass and other hydrophilic substrates can, if necessary, in in a known manner by reaction with Akylsilanen or hexamethyldisilazane can be made hydrophobic. The selection The substrate materials are primarily based on the intended use of the film from the invention manufactured layer elements. For optical elements usually transparent, translucent substrates as Layer carrier used. Will the invention Layer elements, for example in electronics or at electrochemical processes are used as substrates in particular electrically conductive materials such as metals or metallic surface layers, for example Plastic films or glass.

Those serving as carriers for the films according to the invention Depending on the intended use, substrates can have any shape exhibit. For example, you can use film, foil,  be plate-shaped, band-shaped or also cylindrical or can be selected from any other shape. in the in general, the substrates will be flat, act flat substrates such. B. films, foils, plates, Tapes and the like. The surface to be coated Substrates are preferably smooth, as is the case for manufacturing of LB films is common. For flat, flat substrates can the films of the invention on one or both Surfaces of the substrate are applied.

The film according to the invention is characterized by a stable Multi-layer structure with few defects and one through the molecular structure adjustable order in the Layer off.

Such films on substrates are suitable, for example, in optical waveguide systems or for the production of Filters for optical purposes. Because of the low The films are also suitable for critical surface tension Improving the friction properties of materials, for Production of protective layers and for others relevant applications.

The following examples illustrate the invention explained.  

Example 1

27.0 g (0.1 mol) of octadecylamine and 6.7 g (0.05 mol) of terephthalaldehyde are slurried in 400 ml of ethanol and under for 2 hours Reflux cooked. Then allowed to cool and overnight recrystallizes the product from ethanol. 26.2 g are obtained (0.041 mmol) colorless platelets melting at 73-74 ° C.

1 H-NMR (CDCl₃, 100 MHz): δ = 0.85 (t), 1.25 (m), 1.6 (m), 3.6 (t), 7.77 (s), 8.3 (t).

12.74 g (20 mmol) of the Schiff base are dissolved in 200 ml of ethanol in a glass autoclave at 50 ° C., 12 g of freshly prepared Raney nickel are added and the mixture is hydrogenated at 3 bar for 90 minutes. The autoclave is then cooled and let down. The nickel is filtered off and the ethanol is removed on a rotary evaporator. The crude product is obtained in virtually quantitative yield. 1.8 g of the crude product are column chromatographed on silica gel [eluent chloroform / methanol 20: 1 (v / v) ] cleaned. 1.22 g of pure product (white powder) with a melting point of 76-78 ° C. are obtained.

1 H-NMR (CDCl₃, 100 MHz): δ = 0.85 (t), 1.25 (m), 2.28 (m), 2.6 (m), 3.75 (m), 7.26 (s).

According to this regulation, the derivative with two  N-hexadecyl chains produced.

Example 2

36.3 g (0.132 mol) of palmitic acid chloride are dissolved in 400 ml of N-methylpyrrolidone dissolved and a solution of 6.48 g at room temperature (0.06 mol) 1,3-phenylenediamine and 18.24 g (0.08 mol) triethylamine in 200 ml of N-methylpyrrolidone metered in over an hour. The mixture is left to stand at room temperature overnight, and the precipitated solution is suctioned off Product from and recrystallized from chloroform and obtained 25.6 g (44 mmol) of a white powder with a melting point of 133.2- 133.7 ° C.

1 H-NMR (trifluoroacetic acid, 100 MHz): δ = 0.91 (t), 1.1-1.7 (m), 1.7-2.1 (m), 2.76 (t), 7, 4 (m), 7.8 (m).

11.7 g (20 mmol) of the amide prepared above are dissolved in 500 ml dry tetrahydrofuran dissolved at 55 ° C and within 10 minutes to a slurry of 10 g (0.264 mol) LiAlH₄ in 100 ml given dry tetrahydrofuran. Then the mixture becomes 22 Cooked under reflux for hours. After cooling, it is cooled with ice the excess LiAlH₄ by adding 20 ml of water, 15% NaOH and again water destroyed. The failed aluminum hydroxide  is suctioned off and the filtrate is evaporated to dryness. The crude product is dissolved in toluene and washed with water. The organic phase is dried with Na₂SO₄ and after removing the Solvent recrystallized from methanol. 6.5 g (12 mmol) are obtained a light gray powder with a melting point of 88-89 ° C.

1 H-NMR (CDCl₃, 100 MHz): δ = 0.87 (t), 1.0-1.4 (m), 1.4-1.8 (m), 3.08 (t), 5, 8-6.1 (m), 6.96 (t).

All para and meta substituted were made according to this procedure N, N'-dialkyl-substituted phenylenediamines and the N, N'-dialkyl-substituted meta-xylylenediamines with n-tetradecyl, n-hexadecyl and synthesized n-octadecyl residues.

Example 3

135.25 g (0.5 mol) octadecanol and 75.6 g (0.75 mol) triethylamine 1.2 l of dry chloroform are dissolved and by means of ice cooling cooled to 10 ° C. Then one will appear within 1.5 hours Solution of 12.07 g (0.52 mol) of 3,5-dinitrobenzoyl chloride in 350 ml dry chloroform dosed so that the temperature does not exceed 15 ° C rises. When the addition is complete, the mixture is stirred at room temperature  warmed and stirred at room temperature for a further 2 hours. The reaction solution is then three times with 1N HCl, water, 5% Na₂CO solution and again shaken water, the organic Phase dried with Na₂SO₄ and the solvent in vacuo deducted. The crude product is recrystallized from ethanol and in Vacuum dried at 30 ° C. 183 g (0.39 mol, 79% of theory) are obtained. slightly yellow colored crystals with a melting point of 74-78 ° C.

1 H-NMR (CDCl₃, 100 MHz): δ = 0.87 (t), 1.1-1.6 (m), 1.7-2.0 (m), 4.45 (t), 9, 1-9.3 (m).

181 g (0.39 mol) of octadecyl 3,5-dinitrobenzoate are dissolved in 700 ml of toluene dissolved and at 100 ° C and 20 bar H₂ with 5 g of Pt coal Contact hydrogenated in a 2 liter stainless steel autoclave for 2 hours. After filtering off the catalyst, the solvent in Stripped vacuum and the crude product recrystallized from ethyl acetate and ethanol. 142 g (0.35 mol, 90% of theory) of a white are obtained Powder with melting point 86-87 ° C.

1 H-NMR (dimethyl sulfoxide-d⁶, 100 MHz): δ = 0.86 (t), 1.1-1.5 (m), 1.5-1.9 (m), 4.15 (t), 4.9 (s), 6.01 (t), 6.41 (d).

The n-tetradecyl ester, the n-hexadecyl ester, the N-hexadecylamide, the N-octadecylamide and the N, N-dioctadecylamide of 3,5-diaminobenzoic acid.

Example 4 Polycondensate with adipic acid dichloride

4.0 g of the diamine prepared in Example 3 and 7.1 g of triethylamine are dissolved in 50 ml of freshly distilled N-methylpyrrolidone (NMP). A solution of 1.83 g of adipic acid chloride in freshly distilled NMP is added at 5 ° C. with ice cooling and the mixture is stirred for 10 minutes. The mixture is then heated to 70 ° C. and stirred at this temperature for a further 50 minutes. After cooling, 2 g of LiOH are added to dissolve the precipitated product and the polyamide is precipitated by pouring it into 1 liter of methanol. The product obtained (1.6 g) has a molar mass of M _w = 47,000 (light scattering).

Analogous to this regulation (with slight modifications)  also the other synthesized diamines polycondensed with adipic acid will.

Example 5 Polycondensation with diglycol diacid chloride

4.04 g of 3,5-diaminobenzoic acid-N-octadecylamide and 7.1 g of triethylamine are dissolved in 50 ml of freshly distilled N-methylpyrrolidone (NMP). While cooling with ice, a solution of 1.71 g of diglycol diacid chloride in freshly distilled NMP is added and the mixture is stirred for 10 minutes. The mixture is then heated to 70 ° C. and stirred at this temperature for a further 50 minutes. After cooling, 3 g of LiOH are added to dissolve the precipitated product and the polyamide is precipitated by pouring it into 500 ml of methanol. The product obtained (4.04 g) has a molar mass of M _w = 45,000 (light scattering).

Analogous to this regulation (with slight modifications) also the other synthesized diamines with diglycol diacid be polycondensed.

Example 6 Polycondensation with terephthalic acid dichloride

4.85 g of p-xylylene-di- (N, N'-hexadecylamine) are at 50 ° C in 80 ml freshly distilled NMP and suspended within 20 minutes with 2.03 g terephthalic acid dichloride, dissolved in 20 ml dry NMP, offset. The mixture is stirred at 50 ° C for 10 minutes, then heated 70 ° C high and stirred for 50 minutes at this temperature. To cooling to room temperature, 3 g of the reaction mixture LiOH added to redissolve the precipitated product. The The reaction solution is then stirred into 500 ml of methanol to make the precipitated polyamide. 3.91 g of a white product are obtained Powder.

Infrared spectrum (KBr): ν = 2921 cm ^-1 , 2852 cm ^-1 (CH stretching vibrations), ν = 1635 cm ^-1 (amide I), ν = 860 cm ^-1 (1,4-di-subst. Aromatics.

Analogous to this regulation (with slight modifications) also the other synthesized diamines with terephthalic acid and  Phthalic acid can be polycondensed.

Example 7 Layer production using the LB process

A glass slide (76 mm × 26 mm) is cleaned using the following procedure:
The glass is concentrated for one hour in a 60 ° C, freshly prepared mixture of four parts. H₂SO₄ and a part of 30% H₂O₂ placed, rinsed with clean water and sonicated for 15 minutes in a cleaning solution (®Extran AP 11, conc. 2-4 g / l) at 50 ° C. Then it is rinsed thoroughly with clean water and dried in a warm air stream. Treatment with hexamethyldisilazane steam (10 minutes at 70 ° C.) is then carried out for the purpose of hydrophobization.

Multilayers made from the polyamide produced in Example 5 using the Langmuir and Blodgett method on the glass support transferred by 0.25 cm³ in a Langmuir film balance Solution of 5 mg of the polyamide in 10 cm³ of a mixture of 1 ml N-methylpyrrolidone and 9 ml of CH₂Cl₂ on an aqueous subphase a sub-phase temperature of 30 ° C are spread. By The monofilm-covered water surface becomes smaller Thrust adjusted to 30 mN / m and kept constant at this value. The carrier is now vertical from above through the water surface immersed in the film scale (immersion speed: 10-50 mm / min) and after a short break (10 sec) at the bottom Turning point removed again (replacement speed: 10 mm / min). Both in the immersion and in the immersion process transfer a monolayer to the carrier. By multiple Repeat the diving process after waiting one minute At the top reversal point, a total of 20 double layers are transferred. The transfer ratios are 90%. It will, even when transferring 50 or more monolayers, optically clear, Obtain transparent layers.  

Example 8 Ellipsometric layer thickness and refractive index measurements

A silicon wafer (40 mm × 10 mm) is made from a silicon wafer cut out and cleaned as follows:

• 1. 1 hour treatment in a hot (60 ° C), freshly prepared Mixture of one part of 30% H₂O₂ and four parts conc. H₂SO₄. Then rinse with clean water.
• 2. Immerse in NH₄F-buffered HF solution for 30 seconds, and then rinse again with clean water.

After this treatment, the silicon wafers are hydrophobic (contact angle to water: 75 °).

Layers of the polyamide produced in Example 4 are as in Example 7 on the silicon wafer according to the method of Langmuir and Blodgett transferred (subphase: water at 30 ° C, Thrust: 20 mN / m, plunge speed: 20 mm / min, plunge speed: 10 mm / min, pause at the top reversal point: 1 min). It is used both when immersing and when immersing transfer a monolayer (transfer ratio: 95%). It will samples with 10, 20, 30 and 40 monolayers of the polyamide were prepared and ellipsometric the layer thicknesses and the refractive index of the LB films measured (result: refractive index at 633 nm: 1.57, layer thickness: 2.28 nm / monolayer).

Example 9 Thermal stability measurements

A silicon wafer (40 mm × 10 mm) is made from a thermally oxidized Silicon wafer (thickness of the oxide layer: 160 nm) cut out and in an freshly prepared one at 60 ° C for one hour Mixture of one part 30% H₂O₂ and four parts conc. H₂SO₄ laid. After rinsing thoroughly with clean water the plate in an ultrasonic bath at 50 ° C for 15 minutes treated with an alkaline cleaning bath (®Extran AP 11, conc. 2-4 g / l), rinsed thoroughly with clean water and in one warm air stream dried. This is followed by hydrophobization  treatment with hexamethyldisilazane vapor (10 minutes at 70 ° C).

Coating according to the LB method with 8 monolayers takes place with the polyamide produced in Example 4 as described in Example 8.

The coated carrier is in a special apparatus linear temperature gradient (0.5 ° C / sec) heated. During the Heating process is the thickness of the LB layer based on the intensity one perpendicularly polarized reflected from the sample Laser beam (633 nm) measured. The temperature at which the maximum Change in layer thickness takes place in the used Polyamide 180 ° C (for comparison: with LB layers made of 22-tricosenoic acid this temperature is 70 ° C).

Example 10 Critical interfacial energy measurements

A silicon wafer (40 mm × 10 mm) is cleaned as in Example 8 and as in Example 8 with 8 monolayers of that in Example 4 manufactured polyamide coated (temperature of the subphase: 35 ° C).

Liquid droplets are dropped on the surface of the transferred layers brought a series of n-alkanes (C₁₂H₂₆-C₁₆H₃₄) and the contact angle of the liquid drops with the surface measured. From these contact angles, the method of Zisman determined the critical surface tension. It follows a value of 25.1 mN / m. (For comparison: with a polyethylene surface this measurement gives a value of 31 mN / m.)

Example 11 Layer production from a polyamide with a rigid polymer main chain using the LB process

A glass slide is cleaned as described in Example 7. On this glass support is multilayered from that produced in Example 6  Polyamide using the Langmuir and Blodgett method as described in Example 7, grown (subphase: water from 30 ° C, thrust: 15 mN / m, plunge speed: 20 mm / min, plunge speed: 10 mm / min, pause at the top reversal point: 1 Minute, transmission ratio: 82%). A total of 10 double layers mounted on the carrier. It is both transfer a monolayer when immersing as well as when immersing. A clear, transparent layer is obtained.

Example 12 Comparison of the orientation of the alkyl chains of different polycondensates using infrared spectroscopic methods

LB multilayers from those produced in Examples 4 and 6 Polycondensates are made using the Langmuir-Blodgett method, such as described in Examples 7, 8 and 11, as in Example 8 cleaned silicon carriers (20 monolayers each) and fresh layers of gold evaporated onto cleaned glass (thickness of the Layer: 120 nm, transfer of 19 monolayers each) transferred.

Infrared spectra of the substances are among three different ones Conditions measured to make statements about the alkyl chains to be able to.

• 1. Measurement of the IR spectrum of a KBr compact:
  The molecules are isotropically distributed in the KBr compact. The spectrum therefore gives the intensity distribution of the absorptions for an isotropic phase.
• 2. Measurement of the IR spectrum of an LB film on silicon in transmission:
  In this measurement, all molecular groups that vibrate parallel to the substrate surface absorb to a maximum, while all molecular units that vibrate perpendicular to the substrate surface should not absorb or should absorb only weakly.
• 3. Measurement of the IR spectrum of an LB film on a gold surface in reflection with grazing incidence:
  With this measurement, all electrical field components in the metal plane become zero. Therefore, all parts of the molecule that vibrate perpendicular to the substrate surface absorb maximally, while no vibrations are excited parallel to the substrate surface.

Large differences were found in the three different spectra for the layers of the polyamide produced in Example 4: In transmission, the absorption of the CH vibrations between 3000 and 2800 cm ^{-1 is} increased. The same bands are significantly weakened when reflected with grazing incidence. This means that the alkyl chains are oriented essentially perpendicular to the substrate surface.

In the layers of the polymer produced in Example 6 there are no differences between the three different ones Spectra suggesting poorly ordered alkyl chains in the LB layers points out.  

Table 1

Usable dicarboxylic acids

Table 2

Applicable amines

Table 3

Manufactured polyamides

Table 4

Claims (18)

1. Polyamide of the general formula (I) in which
Y is a divalent residue,
X is a divalent radical, the chain of which contains at least two carbon atoms,
A and B, independently of one another, H or C₁-C₂₆-alkyl and
n is an integer over 4,
which has at least one alkyl group C₆-C₁₆, in particular C₁₄-C₂₀ per repeating unit, characterized in that X and / or Y contain at least one CH₂ group in the chain. 2. Polyamide according to claim 1, characterized in that Y in the chain is free of nitrogen. 3. Polyamide according to claim 2, characterized in that Y = (CH₂) _a , where a is an integer from 0 to 10. 4. Polyamide according to claim 2, characterized in that Y = (CH₂OCH₂) _b , where b is an integer from 1 to 13. 5. Polyamide according to claim 2, characterized in that Y is an optionally substituted aromatic group. 6. Polyamide according to claim 5, characterized in that Y is an optionally substituted phenylene or naphthylene radical is.   7. polyamide according to claim 1, characterized in that the radicals X and / or Y are constructed symmetrically. 8. polyamide according to claim 1, characterized in that X in the chain is free of nitrogen. 9. polyamide according to claim 1, characterized in that X is an optionally substituted aromatic group. 10. Polyamide according to claim 8, characterized in that X has the general formula - (CH₂) _c -X¹- (CH₂) _c -, where c = 0, 1 or 2 and X¹ is an optionally substituted aromatic group. 11. Polyamide according to one of claims 5, 9 or 10, characterized in that A and B are hydrogen and the aromatic group is substituted by at least one of the following radicals

• - COOH,
  - CO₂-alkyl, the alkyl group containing 1 to 24 carbon atoms,
  Alkyl with 4 to 24 carbon atoms,
  O-alkyl, where the alkyl group contains 14 to 24 carbon atoms,
  - N (alkyl) ₂, the alkyl groups each containing 10 to 24, in particular 14 to 22, carbon atoms,
  - CO-NR⁴R⁵, where R⁴ and R⁵ independently of one another are hydrogen or alkyl radicals having 1 to 24 carbon atoms.

12. Polyamide according to claim 11, characterized in that the aromatic group is substituted in the 1-position, Represents 3,5-linked phenyl radical.   13. Polyamide according to one of claims 5, 9 or 10, characterized in that A and / or B is a branched or unbranched alkyl radical having 4 to 24 carbon atoms, in particular 14 to 22 carbon atoms, and the aromatic group is substituted by one of the remains

• - OR²,
  - CH₂OR²,
  - SO₃R²,
  - CONHR²,
  - CONR²R³,

where R² and R³ are independently hydrogen, C₁-C₄-alkyl or C₂-C₄-hydroxyalkyl. 14. Polyamide according to claim 1, characterized in that A and / or B is a branched or unbranched alkyl group with 4 to 24 carbon atoms. 15. A method for producing a compound according to Claim 1, characterized in that a diamine of the formula NHA-X-NHB with approximately equimolar amounts of one Dicarboxylic acid COOH-Y-COOH or an activated derivative of this Dicarboxylic acid implements, wherein A, B, X and Y that specified in claim 1 Have meaning. 16. Layer element with a solid layer support and at least one solid, thin one applied thereon Layer of defined uniform regular structure, which consists of at least one polyamide, characterized in that the polyamide at least one Compound according to one of claims 1 to 14.   17. A method for producing a layer element according to Claim 16, characterized in that at least a polyamide according to any one of claims 1 to 14 in one volatile organic water-immiscible Solvent dissolves, the solution at the water / Air spreads the layer after the evaporation of the Solvent compressed and according to the Langmuir-Blodgett Technology transferred to a solid substrate.