DE4327247A1 - Thermoreversible acrylamide polymers, and their use - Google Patents

Abstract

Acrylamide polymers of the formula I <IMAGE> in which the radical A is selected from the radicals -NH-(CH2)aO(CH2)xH, -NH-(CH2)bN((CH2)yH)2 and <IMAGE> where a and b are numbers from 2 to 4, and x and y are 1 or 2, and up to 93 mol% of the radicals A may be replaced by C3-C7-alkylamino groups, form thermoreversible polymers in aqueous solution. Similar polymers in which A is NHB<2>NH form thermoreversible aqueous gels. In this formula, B<2> is in at least some cases bonded intermolecularly and is a divalent, linear, saturated, aliphatic radical having 3-12 carbon atoms, some of which may be replaced by O atoms.

Description

The present invention relates to acrylic acid amide polymers that are formally different from 2- (N-Acryloylamino) -2-methoxyacetic acid and hydrophilic and Have hydrophobic molecular segments. They form gels in water discontinuous swelling behavior or thermoreversible aqueous Polymer solutions. Such solutions have the property Temperature increase above a certain temperature (Lower Critical Solution Temperature (LCST), cloud point, transition temperature (T (Ü)) too segregate. For solutions containing more than 0.1% by weight of the polymer this phase separation induced by temperature increase as a clouding to recognize the solution. Solutions containing more than 30% by weight of the polymer contain, are viscous, but also show a cloudiness Temperature increase.

The LCST and the turbidity interval (temperature range between the beginning clouding and complete clouding) are of the polymer structure dependent.

US Pat. No. 4,822,848 are already thermoreversible Compositions known which contain a polymer in addition to water, the derived from N-tetrahydrofurfurylacrylamide or methacrylamide. Other known thermoreversible systems are solutions with methyl cellulose or poly (N-isopropylacrylamide) in water. For the thermoreversilves in water polymers are numerous Applications have been found. For example, Functionalized polyacrylamide polymers for the separation of substances use aqueous media. Other possible areas of application are temperature controlled light shielding, the temperature controlled Membrane separation and the use as temperature sensors, displays and mechanochemical elements.

It was therefore the task of finding further thermoreversible polymers that are easily accessible and where the cloud point is as needed can be adjusted.

Acrylic acid amide polymers of the general formula (I) have now been found

which are characterized in that the radical A is the same or different residues, which are selected from the residues

where a and b are numbers from 2 to 4 and x and y are 1 or 2, and up to 93 mol% of the radicals A can be replaced by monoalkylamino groups - NHR, where R represents an alkyl radical having 3 to 7 carbon atoms.

According to one embodiment of the invention, there is only a single residue A which a balance between hydrophilic and hydrophobic sections of the molecule having. Examples of these are the radicals -NH (CH₂) ₃O (CH₂) ₂H, -NHCH₂ (CH₃) ₂ and the rest of NH-tetrahydrofurfuryl.

In another embodiment of the invention, the radical A comprises two different radicals, one of the radicals being a hydrophobic monoalkylamino group (in particular -NH (CH₂) _d CH (CH₃) ₂ and -NH (CH₂) _d (CH₂) ₃H with d = 1, 2 or 3) and the other a hydrophilic monoalkylamino group (e.g. -NH (CH₂) ₂OCH₃, -NH (CH₂) ₃OCH₃, -NH (CH₂) ₃N (CH₃) ₂ or HN- (CH₂) _a - (OCH₂) ₂OCH₃) represents.

In a further embodiment, the remainder A comprises two different ones Residues, one of the residues from the group of hydrophobic or hydrophilic Leftovers and the other is chosen from that group that has a balance between Has hydrophilic and hydrophobic molecular sections. Furthermore, it is possible that the residue A consists of at least two different residues, both of which have a balance between hydrophilic and hydrophobic Have molecular segments.

The new acrylic acid amide polymers can be prepared by aminolysis of Poly- [methyl-2- (N-acryloylamino) -2-methoxyacetate] take place. Aminolysis this polymeric ester with n-butylamine is already described in Makromol. Chem. Rapid. Commun. 12.403 (1991). The polyamides described there however, do not form thermally reversible aqueous solutions. It is an advantage of this manufacturing process that the starting substance Methyl-2-N-acryloylamino-2-methoxyacetate (= MAGME) as technical Product is easily accessible and a synthetic route for thermoreversible Polymers avoiding acryloyl chloride and acrylamide derivatives enables. The production of the individual polymers can be done in one step Poly-MAGME or MAGME copolymers or by two-stage aminolysis respectively. The use of amine mixtures enables targeted Setting the LCST. The haze interval for the acrylic acid amide Polymers containing at least two different radicals A are smaller with increasing molecular weight.

The polymers according to the invention form thermoreversible aqueous solutions, in particular solutions containing 0.1 to 50 wt .-% polymer. In some Cases of thermal reversibility only occur when a water-soluble salt is added, preferably up to 15% by weight of a water-soluble salt the first or second main group of the periodic table. Is preferred from economic reasons sodium chloride.  

Table 1 shows for some acrylic acid amide polymers of the formula I in which AH a monoamine or diamine means the solubility behavior in water and 10% aqueous sodium chloride solution listed.

Table 1

In Table 2, the haze interval of an aqueous solution of polymers is the Formula I indicated that with two different monoamines HA in different molar ratios were produced. The monoamines were Methoxyethylamine and n-butylamine.

Table 2

The polymers according to the invention are suitable for the production of thermoreversible light shields, the z. B. used for greenhouses can, for temperature sensors, for heat sensitive displays and for thermoreversible thickener. By using a mixture from a functionalized monoamine and a hydrophilic / hydrophobic Monoamine in aminolysis can be functionalized thermoreversible polymers are shown, for example, for the separation of substances (Heavy metals, antibodies, etc.) from an aqueous solution.  

Surprisingly, it has been shown that closely related acrylic acid amide Polymers are able to form gels in the presence of water.

The invention therefore relates to acrylic acid amide polymers of the general type Formula (II).

B represents a mixture of B¹ and B², B¹ being selected from the groups

a and b are numbers from 2 to 4 and x and y are 1 or 2. B² is a divalent, linear, saturated, aliphatic radical with 3 to 12 carbon atoms, which is at least partially intermolecularly bound. The C atoms of B² can be partially replaced by O atoms, which makes the hydrophilic Character is enhanced.

The divalent radicals B² are part of bisamide bridges lead at least partially to crosslinking of polymer chains and are apparently required to form thermally reversible gels. The atomic ratio O / C in the remainder of B² is preferably 0: 1 to 1: 3 Molar ratio B¹ / B² is generally 9: 1 to 1: 9. It is advantageous if contains at least one of the radicals B¹ and B² oxygen, so that one  adequate balance between hydrophilic and hydrophobic groups is available. Generally the atomic ratio is Carbon / oxygen in the residue B 5: 1 to 10: 1.

To produce a gel-forming polymer, a polymer of the formula (III)

with a primary monoamine of the formula NH₂R, NH₂ (CH₂) _a O (CH₂) _x H, NH₂ (CH₂) _b N ((CH₂) _y H) ₂ or tetrahydrofurfurylamine and a diamine of the formula NH₂-B²-NH₂, wherein a and b are integers from 2 to 4, x and y are 1 or 2 and R represents an alkyl radical with 3 to 7 C atoms and B² is a divalent, linear, saturated, aliphatic radical with 3 to 12 C atoms, which can be partially replaced by O atoms, the molar ratio of primary monoamine / diamine is 1: 9 to 9: 1 and the amount of amine is sufficient to convert all methyl ester groups into amide groups.

Thermoreversible gels can be used in relation to the amines or Diamines are presented according to the same principles as the thermo-reversible ones "Copolymers". For example, a hydrophilic primary amine component such as Example 2-methoxyethylamine, with a hydrophobic diamine component, such as for example 1,6-diaminohexane, can be combined or vice versa hydrophobic primary amine, for example n-butylamine, with a hydrophilic Diamine, for example 1,5-diamino-3-oxapentane.

But it can also be a primary amine, which in the case of complete Implementation PMAGME would result in a thermo-reversible homopolymer be used with a diamine that is about the same Has a hydrophilic / hydrophobic balance like the amine used. An example  this is the combination of the primary amine 3-ethoxypropylamine with the Diamine 1,12-diamino-4,9-dioxadodecane.

The polymer of formula (III) can first be primary with at least 1 mol Add monoamine per ethyl ester grouping, stop the reaction and then not at least 1 mole of diamine per mole to the reaction product add converted ethyl ester grouping and after complete aminolysis isolate the resulting polymer.

Alternatively, the polymer of formula (III) can first be used with a deficit add diamine, at least 1 mol primary after the reaction has ended Add monoamine per unreacted ethyl ester grouping and after complete aminolysis isolate the resulting polymer.

Will Poly-MAGME with a diamine that has a hydrophilic / hydrophobic balance has, crosslinked and then the unreacted ester groups of Poly-MAGME aminolyzed with a hydrophilic / hydrophobic amine, so obtained gels with a discontinuous swelling behavior in water. The gels are swellable in water at a low temperature. When heating up Water is added and the partially dewatered gel shrinks. These gels can for temperature-controlled release of active substances u. serve.

The invention is illustrated by the following examples.

example 1

After that in Makromol. Chem. Rapid. Commun. specified procedure was the aminolysis of Poly-MAGME with a mixture of 5 mol 3-ethoxy-n-propylamine and 1 mol of n-hexylamine performed. An aqueous one Solution of the polymer obtained began to thermoreversible at about 20 ° C. tarnish.  

Example 2

The procedure of Example 1 was repeated; however, Poly-MAGME was added implemented pure 3-ethoxypropylamine. An aqueous solution of the obtained Polymers had a cloud point of 46 ° C (beginning of clouding: 46.5 ° C, about 6% residual optical transmission at 55 ° C, about 50% remaining optical transmittance at 49 ° C).

Example 3

An aqueous solution of 10 g / l was prepared from the polymer of Example 2. The solution was heated to 60 ° C and slowly cooled. The relative viscosity (η / c) was measured. The dependence on the temperature is shown in Fig. 1. In the range of 55 ° C to 25 ° C, the viscosity increases as the temperature drops, as expected. It is surprising that the viscosity decreases in the range from 65 ° C to 55 ° C with falling temperature.

Example 4

Following the procedure of Example 1, Poly-MAGME with tetrahydro furfurylamine implemented. An aqueous solution of the polymer obtained (5 g / l) was heated to 60 ° C. When the solution cooled to 50 ° C the decreased relative viscosity (η / c) from 3.75 (ml / g) to 2.5 ml / g.

Example 5

The polymer of Example 2 was dissolved in water with different levels of sodium chloride and sodium benzoate. With increasing concentration of sodium chloride the LCST decreased and with increasing concentration of sodium benzoate the LCST rose after it had only decreased with a 1% by weight solution. The dependence of the occurrence of the thermoreversible phase on the salt concentration is shown in FIG. 2.

Example 6

Example 1 was repeated, but the molar ratio used was Ethoxy-n-propylamine / hexylamine 15: 1. The aqueous solution prepared had a turbidity interval of 36 to 37 ° C.

Example 7

Poly-MAGME was mixed with a mixture of 5 moles of 3-ethoxypropylamine and 2 mol of 2-methoxyethylamine reacted. The polymer obtained gave one aqueous solution which clouded at 52 to 54 ° C. As the molar ratio to 5: 1 was increased, the cloud point became about 2 K to higher temperatures postponed.

Example 8 Preparation of poly- (N- (3-ethoxypropylcarbamoyl-methoxy-methyl) acrylamide)

A solution of 1.00 g (5.8 mmol) poly [methyl-2- (N-acryloylamino) -2- methoxyacetate] (PMAGME), 2.10 ml (17.4 mmol) of 3-ethoxypropylamine and 10 ml of ethyl acetate was heated at 70 ° C. After 15 hours the Polymer solution dropped into 200 ml of diethyl ether, the product being colorless precipitate failed. The resulting polymer was filtered off washed several times with diethyl ether and dried at 60 ° C in a vacuum. The yield was 0.99 g (70%). The "homopolymer" has a cloud point at 46 ° C.

Example 9 Preparation of poly (N- (isopropylcarbamoyl-methoxy-methyl) -acrylamide)

A solution of 0.50 g (2.9 mol) of poly [methyl-2- (N-acryloylamino) -2- methoxyacetate] (PMAGME) and 5 ml of isopropylamine was at 40 ° C under Reflux heated. After 15 h the polymer solution was in 200 ml of diethyl ether  added dropwise, the product precipitating out as a colorless precipitate. The the resulting polymer was filtered off and dissolved in 4 ml of acetone for purification and precipitated again in 200 ml of diethyl ether. The polymer was filtered off washed several times with diethyl ether and dried at 60 ° C in a vacuum. The yield was 0.34 g (45%). The "homopolymer" has a cloud point at 43 ° C.

Example 10 Preparation of poly (N- (3-ethoxypropylcarbamoyl-methoxy-methyl) -acrylamide) -co- (N- (n - hexylcarbamoyl-methoxy-methyl) acrylamide))

A solution of 1.00 g (5.8 mmol) poly [methyl-2- (N-acryloylamino) -2- methoxyacetate], 17.4 mmol amine mixture consisting of 14.5 mmol (1.74 ml) 3-ethoxypropylamine and 2.9 mmol (0.38 ml) hexylamine and 10 ml Ethyl acetate was heated at 70 ° C. After 20 hours the Polymer solution dropped into 200 ml of diethyl ether, the product being colorless precipitate failed. The polymer obtained was filtered off several times washed with diethyl ether and dried at 60 ° C in a vacuum. The Yield was 0.92 g. The turbidity temperature of the copolymer is 24 to 26 ° C.

Example 11 Preparation of poly- (N- (n-butylcarbamoyl-methoxy-methyl) -acrylamide) -co- (N- (2-methox-yethyl-methoxy-methyl) -acrylamide))

A solution of 1.00 g (5.8 mmol) poly [methyl-2- (N-acryloylamino) -2- methoxyacetate], 17.4 mmol amine mixture consisting of 8.7 mmol (0.86 ml) n-butylamine and 8.7 mmol (0.74 ml) 2-methoxyethylamine and 10 ml Ethyl acetate was refluxed at 70 ° C. After 15 h the solvent and the excess amine are removed in vacuo Polymer taken up in acetone and the polymer solution in 200 ml of diethyl ether added dropwise, the product precipitating out as a colorless precipitate. After this  The polymer was decanted off at 60 ° C. in vacuo dried. The yield was 0.85 g. The turbidity temperature of the copolymer is 32 to 44 ° C.

Example 12

Preparation of poly [methyl-2-2 crosslinked with 1,12-diamino-4,9-dioxadodecane (N-acryloylamino) -2-methoxyacet) -co- (N-3-ethoxypropyl-methoxy-methyl- acrylamide), by two-stage aminolysis, only with 3-ethoxypropylamine was incompletely aminolyzed.

A) Incomplete aminolysis of PMAGME with 3-ethoxypropylamine

A solution of 1.00 g (5.8 mmol) poly [methyl-2- (N-acryloylamino) -2- methoxyacetate], 0.70 ml (5.8 mmol) of 3-ethoxypropylamine and 5 ml of THF heated at 60 ° C. The reaction was stopped after 4 h and the solution in Diethyl ether was added dropwise, the polymer precipitating out as a colorless precipitate. The product was filtered off, washed several times with diethyl ether and at 60 ° C dried in vacuo. A white powder is obtained. The yield was 1.35 g. Ester fraction: 30% (1 H-NMR, 90 MHz, IR (KBr))

B) Aminolysis of the incompletely aminolyzed product with 1,12-diamino-4,9-dioxadodecane

A solution of 0.30 g (1.34 mmol) poly [(methyl-2- (N-acryloylamino) -2-methoxyacetate) -co-N- (3-ethoxypropylcarbamoyl-methoxy-methyl) -acrylam-id], 0.043 ml of 1,12-diamino-4,9-dioxadodecane and 1 ml of THF is heated at 40 ° C. under reflux for 20 h. After the solvent has been decanted off, the resulting gel is placed in 10 ml of THF in order to remove excess amine. The solvent is then decanted off and the gel is dried in vacuo at 60.degree.
Degree of swelling (water): Q _w (20 ° C) = 3.0; Q _w (80 ° C) = 1.7

Example 13

Preparation of poly- (N- (3--) with 1,12-diamino-4,9-dioxadodecane ethoxypropylcarbamoyl-methoxy-methyl) acrylamide) by two-stage Aminolysis, incomplete until 1,12-diamino-4,9-dioxadodecane was aminolyzed.

A) Incomplete aminolysis of PMAGME with 1,12-diamino-4,9-dioxadodecane

A solution of 0.42 g (2.43 mmol) poly [methyl-2- (N-acryloylamino) -2- methoxyacetate], 0.077 ml (0.36 mmol) 1,12-diamino-4,9-dioxadodecane and 2 ml of THF was heated at 60 ° C under reflux. After 1 1/2 hours is a gel emerged. To ensure that the diamine used is implemented as completely as possible To achieve, further THF was added and a further 3 h at 60 ° C. Reflux heated. The solvent was then decanted off and the gel added 60 ° C dried in vacuo. A light yellow, glass-like product is obtained. Percentage of esters: 60% (IR (KBr))

B) Aminolysis of the incompletely aminolyzed product with 3-ethoxypropylamine

A solution of 0.35 g (1.75 mmol) of poly- [methyl-2- (N-acryloylamino) -2-methoxyacetate] crosslinked with 1.12-diamino-4,9-dioxadodecane], 0.44 ml of 3- Ethoxypropylamine and 5 ml THF was heated at 60 ° C under reflux for 30 h. The solvent was then decanted off and the gel was placed several times in 10 ml of THF in order to separate off the excess amine. The gel was then dried at 60 ° C in a vacuum. A light yellow, glass-like product is obtained.
Degree of swelling (water): Q _w (20 ° C) = 3.8
Q _w (80 ° C) = 2.1.

Claims (16)

1. Acrylic acid amide polymers of the general formula I characterized in that the radical A consists of the same or different radicals which are selected from the radicals where a and b are numbers from 2 to 4 and x and y are 1 or 2, and up to 93 mol% of the radicals A can be replaced by groups of the formula -NHR, where R is an alkyl radical with 3 to 7 carbon atoms represents. 2. Polymer according to claim 1, characterized in that R represents (CH₂) _a (CH₂) ₃H or (CH₂) _a CH (CH₃) ₂, where a is an integer from 0 to 3. 3. Aqueous solution containing 0.1 to 50% by weight of the polyacrylic acid amide Polymers according to Claim 1 and optionally up to 15% by weight of one water-soluble salt of an element of the first or second main group. 4. Use of the polyacrylic acid amide polymers according to claim 1 for thermoreversible light barriers.   5. Use of the polyacrylic acid amide polymer according to claim 1 for thermoreversible thickener. 6. Acrylic acid amide polymer of the general formula (II) characterized in that B is a mixture of B¹ and B², B¹ being selected from the groups where a, b, x and y have the meaning given in claim 1 and B² is a divalent, linear, saturated, aliphatic radical having 3 to 12 carbon atoms, which can be partially replaced by O atoms and B² is at least partially bound intermolecularly is. 7. Polymer according to claim 6, characterized in that the Atomic ratio O / C in the rest B² is 0: 1 to 1: 3. 8. Polymer according to claim 6, characterized in that the molar ratio B¹ / B² is 9: 1 to 1: 9. 9. Polymer according to claim 6, characterized in that at least one the radicals B¹ and B² contain oxygen.   10. Polymer according to claim 9, characterized in that the Atomic ratio C / O in (B¹ + B²) is 5: 1 to 10: 1. 11. Polymer according to claim 5, characterized in that the (C₃-C₇) - alkyl group has the structure (CH₂) _a (CH₂) ₃H or (CH₂) _a CH (CH₃) ₂, where a is an integer from 0 to 3 is. 12. Aqueous gel containing at least one polymer according to claim 6. 13. Use of a gel according to claim 12 for irrigation systems. 14. A process for the preparation of a polymer according to claim 6, characterized in that a polymer of the formula (III) with a primary monoamine of the formula NH₂R, NH₂ (CH₂) _a O (CH₂) _x H, NH₂ (CH₂) _b N ((CH₂) _y H) ₂ or tetrahydrofurfurylamine and a diamine of the formula NH₂-B²-NH₂, where a and b are integers from 2 to 4, x and y are 1 or 2 and R has the meaning given in claim 1 and B² is a divalent, linear, saturated, aliphatic radical having 3 to 12 carbon atoms, which is in part represented by O -Atoms can be replaced, the molar ratio of primary monoamine / diamine is 1: 9 to 9: 1 and the amount of amine is sufficient to convert all methyl ester groups into amide groups. 15. The method according to claim 14, characterized in that one Polymer of formula (III) initially with at least 1 mol of primary monoamine per Ethyl ester group added, the reaction is stopped and then to Reaction product at least 1 mole of diamine per mole of unreacted Ethyl ester group is added and after complete aminolysis resulting polymer isolated. 16. The method according to claim 14, characterized in that one Polymer of formula (III) first mixed with a deficit of diamine, one after completion of the reaction at least 1 mole of primary monoamine per non converted ethyl ester grouping is added and after complete Aminolysis isolated the resulting polymer.