DIBLOCK COPOLYMERS AND THEIR USE AS SURFACTANTS

Abstract

The present invention relates to the use of diblock copolymers as surfactants, and to a method for producing diblock copolymers, containing a hydrocarbon-containing block A and a polyether carbonate-containing block B, by attaching alkylene oxide and carbon dioxide to H-functional starters in the presence of a double metal cyanide catalyst, characterized in that the H-functional starter has an OH functionality of 1, and the H-functional starter is selected from one or more compounds of the group of monofunctional alcohols having 10 to 20 carbon atoms, and no further catalyst is used in addition to the DMC catalyst.

Claims

1. A process for the preparation of diblock copolymers which comprise, a hydrocarbon-containing block A and a polyethercarbonate-containing block B, comprising adding of alkylene oxide and carbon dioxide onto an H-functional starter substance in the presence of a double metal cyanide catalyst, wherein the H-functional starter substance has an OH-functionality of 1, the H-functional starter substance comprises a monofunctional alcohol having 10 to 20 carbon atoms, or a mixture of monofunctional alcohols having 10 to 20 carbon atoms: and no additional catalyst other than the DMC catalyst is present.

2. The process as claimed in claim 1, wherein the H-functional starter substance comprises an aliphatic monofunctional alcohol having 10 to 20 carbon atoms, or a mixture of aliphatic monofunctional alcohols having 10 to 20 carbon atoms.

3. The process as claimed in claim 1, wherein the H-functional starter substance has a structure corresponding to the general formula (I)
R.sup.1OH (I), wherein R.sup.1 represents a compound comprising an alkyl group, an alkenyl group or an alkynyl group.

4. The process as claimed in claim 1, wherein the H-functional starter substance comprises a monofunctional alcohol having 10 to 18 carbon atoms, or a mixture of monofunctional alcohols having 10 to 18 carbon atoms.

5. The process as claimed in claim 1, wherein the H-functional starter substance comprises a of decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, or mixtures thereof.

6. The process as claimed in claim 1, wherein the alkylene oxide comprises ethylene oxide or a mixture of at least two alkylene oxides containing ethylene oxide.

7. The process as claimed in claim 6, wherein the mixture of at least two alkylene oxides containing ethylene oxide is free of propylene oxide.

8. The process as claimed in any of claim 1, wherein the molar ratio of H-functional starter substance to alkylene oxide is 1.0:1.0 to 1.0:30.0.

9. The process as claimed in claim 1, comprising () initially charging the H-functional starter substance or a suspension medium and removing any water and/or other volatile compounds by elevated temperature and/or reduced pressure (drying), wherein the DMC catalyst is added to the H-functional starter substance or to the suspension medium before or after the drying, () adding a portion (based on the total amount of alkylene oxides used in the activation and copolymerization) of alkylene oxide to the mixture resulting from step () to achieve activation, wherein this addition of a portion of alkylene oxide may optionally be effected in the presence of CO.sub.2 and wherein the temperature peak (hotspot) which occurs due to the subsequent exothermic chemical reaction and/or a pressure drop in the reactor is then awaited in each case, and wherein step () for achieving activation may also be effected repeatedly, () adding alkylene oxide, carbon dioxide and optionally H-functional starter substance to the mixture resulting from step (), wherein at least one H-functional starter substance is added at least in one of steps () and ().

10. The process as claimed in claim 1, wherein the H-functional starter substance is metered into the reactor continuously during the reaction.

11. A surfactant comprising the diblock copolymer prepared by a process as claimed in claim 1.

12. Diblock copolymers comprising the reaction product of an alkylene oxide and carbon dioxide onto a H-functional starter substance in the presence of a double metal cyanide catalyst, wherein the H-functional starter substance has a hydroxyl functionality of 1, and comprises a monofunctional alcohol having 10 to 20 carbon atoms or a mixture of monofunctional alcohols having 10 to 20 carbon atoms; and no additional catalysts other than the double metal cyanide catalyst are present.

13. Diblock copolymers as claimed in claim 12, wherein the diblock copolymers have a polydispersity index of less than 2.00.

14. Diblock copolymers as claimed in claim 12, wherein the proportion of incorporated CO.sub.2 (% by weight) in the diblock copolymers, based on the portion of the polymer that was formed under CO.sub.2, is 1.0% to 30.0% by weight.

15. Diblock copolymers as claimed in claim 12, wherein the diblock copolymers have a number-average molecular weight of 200 g/mol to 3000 g/mol.

Description

EXAMPLES

[0141] The present invention is elucidated further by the examples which follow, but without being restricted thereto.

Test Methods

[0142] The HLB value of the diblock copolymers is determined by utilizing the correlation between phase inversion temperature (PIT) and HLB value. Here, the PIT is the temperature at which a water-in-oil emulsion becomes an oil-in-water emulsion. The PIT of the diblock copolymers is ascertained by way of measurements of the electrical conductivity as a function of the temperature made on an emulsion of water (47% by weight), octane (47% by weight) and the respective diblock copolymer (6% by weight). The PIT is identifiable by a characteristic drop in the conductivity. Due to the correlation between the PIT and HLB value, the HLB value of the diblock copolymers can be ascertained by means of a comparison with known nonionic surfactants.

[0143] The hydrolytic degradability of the inventive diblock copolymers and also of the comparative substances used (cf. table 1: hydrolytic degradation) was ascertained at 25 C. and also at 60 C. by the following general method: The degradation of the diblock copolymers was determined by storage of 5% by weight of the diblock copolymer in water at 25 C. and at 60 C. over a period of 30 days. A solution of 2.5 g of the diblock copolymer in 47.5 g of water having a pH of 3, 7 and 11 was prepared in each case for each diblock copolymer. In this case, the pH was adjusted for the pH of 3 by addition of a hydrochloric acid solution having a concentration of 10 mol/l of HCl (Merck Chemicals GmbH), the pH of 7 by addition of an aqueous solution having a concentration of 0.05 mol/l of the buffer phosphate buffer 7.4 (Merck Chemicals GmbH) and for the pH of 11 by addition of a sodium hydroxide solution having a concentration of 3 mol/l of NaOH (Merck Chemicals GmbH). There was a hydrolytic degradability of the diblock copolymers in solution if a reduction of the cloud point by at least 5% and a decrease in the surface tension by at least 10% are observed in the solutions within 30 days. The surface tension is measured here using a DCAT 11 du Noy ring tensiometer from Dataphysics Instruments GmbH. This measurement involves dipping a platinum ring having a diameter of 18.7 mm into the solution containing the diblock copolymer and withdrawing it again. When withdrawing the ring from this solution, part of the solution is carried along by the ring, which results in an increase in the force expended. The maximum measured force which is required to pull the ring out of the solution containing the diblock polymer is proportional to the surface tension. The cloud point is the temperature from which the solution containing the diblock copolymer separates into two phases and changes from a clear to a cloudy solution. Any observable hydrolytic degradability of the diblock copolymer is identified by an x in table 1, where represents a lack of hydrolytic degradation of the diblock copolymer.

[0144] In order to determine the temperature dependence of the emulsification characteristics of the diblock copolymers, a mixture of water (47% by weight), octane (47% by weight) and diblock copolymer (6% by weight) is prepared and admixed with butanol. This mixture consists of two phases at 25 C. and on increasing the temperature forms an emulsion as a third phase from the two phases. For this, the sample is heated in a water bath and the temperature range in which the emulsion remains stable is visually assessed. The temperature range thus ascertained is reported in table 1 as temperature dependence of the emulsification characteristics.

[0145] For the determination of the molar masses, the diblock copolymers are dissolved in methanol (approx. 1 mg/ml) and investigated in an HPLC/MS analysis. The HPLC is characterized by a Grom-Sil-120-OSD-4 HE column and a water/acetonitrile eluent gradient with 0.1% by weight of formic acid in each case. Under these conditions, the homologs of the diblock copolymers elute in a broad peak which is detected by a mass spectrometer (LTQ Orbitrab XL with ESI ionization). This analysis shows a spectrum of molar masses which can be assigned to the individual homologs. The intensity of the peaks is attributed to the frequency of the homologs in the sample and is used for the determination of the number-average molar mass M.sub.n (also referred to as molecular weight) and for the calculation of the polydispersity index (PDI).

[0146] The mole fraction of the carbonate incorporated in the polymer in the reaction mixture is determined by means of .sup.1H NMR (Bruker, DPX 400, 400 MHz; pulse program zg30, relaxation delay d1: 10 s, 64 scans) and calculated according to formula (VIII). Each sample was dissolved in deuterated chloroform. The relevant resonances in the .sup.1H NMR are based on TMS=0 ppm. The following abbreviations are used for formula (VIII): [0147] F(4.5)=area of the resonance at 4.5 ppm for cyclic ethylene carbonate (corresponds to 4 protons). [0148] F(4.3)=area of the resonance at 4.3 ppm for polyethylene glycol carbonate polyol (corresponds to 4 protons). [0149] F(4.24.3)=area of the resonance at 4.23.3 ppm for polyethylene glycol (corresponds to 4 protons) and two protons for dodecanol/hexadecanol. [0150] F(0.9)=area of the resonance at 0.9 ppm for dodecanol/hexadecanol (corresponds to 3 protons in the terminal methyl group).

[0151] Taking account of the relative intensities, the values for the polymer-bound carbonate (linear carbonate LC) in the reaction mixture were converted to mol % as per the following formula (VIII):

[00001]$\begin{array}{cc}\mathrm{LC}=\frac{0.25*F\left(4.3\right)}{\begin{array}{c}0.25*F\left(4.3\right)+\left[0.25*F\left(4.2-3.3\right)-0.67*F\left(0.9\right)\right]+\\ 0.25*F\left(4.5\right)+0.33*F\left(0.9\right)\end{array}}*100& \left(\mathrm{VIII}\right)\end{array}$

[0152] The proportion by weight (in % by weight) of polymer-bound carbonate (LC) in the reaction mixture was calculated by formula (IX),

[00002]$\begin{array}{cc}{\mathrm{LC}}^{}=\frac{0.25*F\left(4.3\right)*88}{D}*100.Math.\%& \left(\mathrm{IX}\right)\end{array}$

where the value of D (denominator D) is calculated by formula (X):

D=0.25*F(4.3)*88+0.25*F(4.5)*88+[0.25*F(4.23.3)0.67*F(0.9)]*44+0.33*F(0.9)*M (X)

[0153] The factor of 88 results from the sum of the molar masses of CO.sub.2 (molar mass 44 g/mol) and of ethylene oxide (molar mass 44 g/mol); the factor of 44 results from the molar mass of ethylene oxide. The factor M is 242 for hexadecanol and 186 for dodecanol.

[0154] The proportion by weight (in % by weight) of cyclic carbonate (CC) in the reaction mixture was calculated by formula (XI),

[00003]$\begin{array}{cc}C.Math.C^{}=\frac{0.2.Math.5^{*}.Math.F\left(4.5\right)*8.Math.8}{D}.Math.100.Math.\%& \left(\mathrm{XI}\right)\end{array}$

where the value of D is calculated by formula (X).

[0155] In order to calculate the composition based on the polymer component (consisting of polyether, which was constructed from ethylene oxide during the activation steps taking place under CO.sub.2-free conditions, and diblock copolymer, constructed from starter, ethylene oxide and carbon dioxide during the activation steps taking place in the presence of CO.sub.2 and during the copolymerization) from the values for the composition of the reaction mixture, the non-polymeric constituents of the reaction mixture (that is to say cyclic ethylene carbonate) were mathematically eliminated. The proportion by weight of the carbonate repeating units in the diblock copolymer was converted into a proportion by weight of carbon dioxide by means of the factor F=44/(44+44). The figure for the CO.sub.2 content in the diblock copolymer (incorporated CO.sub.2; see examples which follow and table 1) is normalized to the diblock copolymer molecule which has formed in the copolymerization and the activation steps.

[0156] Rheological measurements for the determination of the zero shear rate viscosities were carried out using a Bohlin Gemini 200 HR nano rheometer instrument (Malvern Instruments) using the cone geometry. The zero shear rate viscosity was ascertained at 25 C. in an aqueous solution containing 45% to 60% by weight of the measured diblock copolymer. This involved measuring the viscosity as a function of the shear rate in a shear rate range from 0.00014 Hz to 50 Hz. The results of the zero shear rate viscosities are reported in table 2.

Raw Materials Used

[0157] 1-Hexadecanol (Sigma-Aldrich)

[0158] 1-Dodecanol (Sigma-Aldrich)

[0159] Ethylene oxide (Linde AG)

[0160] Marlipal 24/90diblock copolymer made from a C.sub.12-C.sub.14 alcohol mixture and ethylene oxide (Sasol)

[0161] Lutensol AT 13diblock copolymer made from a C.sub.16-C.sub.18 alcohol mixture and ethylene oxide (BASF SE)

Example 1: Preparation of a Diblock Copolymer (DBC-1) Using 1-hexadecanol as H-Functional Starter Substance

[0162] Step ():

[0163] A 2 liter pressure reactor with gas metering device was initially charged with 200 mg of dried DMC catalyst (prepared according to example 6 of WO-A 01/80994) and 242.40 g of 1-hexadecanol. The suspension was then heated to 130 C. and a constant nitrogen stream and a reduced pressure of 100 mbar were applied for 30 min.

[0164] Step ():

[0165] The reactor was subsequently charged with 50 bar of CO.sub.2 at 130 C. and 10 g of ethylene oxide (EO) were metered into the reactor all at once. Activation of the catalyst was perceptible by a temperature peak (hotspot) and by a pressure drop to the starting pressure (50 bar). The procedure was repeated once more.

[0166] Step ():

[0167] After activation had occurred, the temperature was adjusted to 100 C. and 586.0 g of ethylene oxide were metered into the reactor within 3 h. The progress of the reaction was monitored via the CO.sub.2 consumption, with the pressure in the reactor being held constant at 50 bar by means of continuously controlled further metered addition. After completion of EO addition, stirring was continued at the pressure indicated above until no further consumption of CO.sub.2 was observed (approximately 1 hour). The product was subsequently removed from the reactor and freed of volatile components on a rotary evaporator.

[0168] The diblock copolymer thus prepared features the following properties:

[0169] Incorporated CO.sub.2 (% by weight) based on the portion of the polymer that was formed under CO.sub.2: 6.1% by weight;

[0170] The selectivity c/l was 1.16 and the polydispersity was 1.02.

Example 2: Preparation of a Diblock Copolymer (DBC-2) Using 1-dodecanol as H-Functional Starter Substance

[0171] Step ():

[0172] A 2 liter pressure reactor with gas metering device was initially charged with 200 mg of dried DMC catalyst (prepared according to example 6 of WO-A 01/80994) and 144.10 g of 1-dodecanol. The suspension was then heated to 130 C. and a constant nitrogen stream and a reduced pressure of 100 mbar were applied for 30 min.

[0173] Step ():

[0174] The reactor was subsequently charged with 50 bar of CO.sub.2 at 130 C. and 10 g of ethylene oxide were metered into the reactor all at once. Activation of the catalyst was perceptible by a temperature peak (hotspot) and by a pressure drop to the starting pressure (50 bar). The procedure was repeated once more.

[0175] Step ():

[0176] After activation had occurred, the temperature was adjusted to 100 C. and 504.6 g of ethylene oxide were metered into the reactor within 3 h. The progress of the reaction was monitored via the CO.sub.2 consumption, with the pressure in the reactor being held constant at 50 bar by means of continuously controlled further metered addition. After completion of EO addition, stirring was continued at the pressure indicated above until no further consumption of CO.sub.2 was observed (approximately 1 hour). The product was subsequently removed from the reactor and freed of volatile components on a rotary evaporator.

[0177] The diblock copolymer thus prepared features the following properties:

[0178] Incorporated CO.sub.2 (% by weight) based on the portion of the polymer that was formed under CO.sub.2: 5.0% by weight;

[0179] The selectivity al was 1.4 and the polydispersity was 1.03.

Example 5: Preparation of a Diblock Copolymer (DBC-3) Using 1-dodecanol as H-Functional Starter Substance

[0180] Step ():

[0181] A 2 liter pressure reactor with gas metering device was initially charged with 160 mg of dried DMC catalyst (prepared according to example 6 of WO-A 01/80994) and 142.6 g of 1-dodecanol. The suspension was then heated to 130 C. and a constant nitrogen stream and a reduced pressure of 100 mbar were applied for 30 min.

[0182] Step ():

[0183] The reactor was subsequently charged with 5 bar of N.sub.2 and 10 g of ethylene oxide were metered into the reactor all at once. Activation of the catalyst was perceptible by a temperature peak (hotspot) and by a pressure drop to the starting pressure (5 bar). The reactor was subsequently charged with 20 bar of CO.sub.2.

[0184] Step ():

[0185] After activation had occurred, the temperature was adjusted to 100 C. and 454.6 g of ethylene oxide were metered into the reactor within 4 h. The progress of the reaction was monitored via the CO.sub.2 consumption, with the pressure in the reactor being held constant at 50 bar by means of continuously controlled further metered addition. After completion of EO addition, stirring was continued at the pressure indicated above until no further consumption of CO.sub.2 was observed (approximately 1 hour). The product was subsequently removed from the reactor and freed of volatile components on a rotary evaporator.

[0186] The diblock copolymer thus prepared features the following properties:

[0187] Incorporated CO.sub.2 (% by weight) based on the portion of the polymer that was formed under CO.sub.2: 2.9% by weight;

[0188] The selectivity c/l was 0.86 and the polydispersity was 1.03.

Example 6: Preparation of a Diblock Copolymer (DBC-4) Using 1-dodecanol as H-Functional Starter Substance

[0189] Step ():

[0190] A 2 liter pressure reactor with gas metering device was initially charged with 159 mg of dried DMC catalyst (prepared according to example 6 of WO-A 01/80994) and 144.46 g of 1-dodecanol. The suspension was then heated to 130 C. and a constant nitrogen stream and a reduced pressure of 100 mbar were applied for 30 min.

[0191] Step ():

[0192] The reactor was subsequently charged with 50 bar of CO.sub.2 at 130 C. and 10 g of ethylene oxide were metered into the reactor all at once. Activation of the catalyst was perceptible by a temperature peak (hotspot) and by a pressure drop to the starting pressure (50 bar). The procedure was repeated once more.

[0193] Step ():

[0194] After activation had occurred, the temperature was adjusted to 100 C. and 454.6 g of ethylene oxide were metered into the reactor within 4 h. The progress of the reaction was monitored via the CO.sub.2 consumption, with the pressure in the reactor being held constant at 50 bar by means of continuously controlled further metered addition. After completion of EO addition, stirring was continued at the pressure indicated above until no further consumption of CO.sub.2 was observed (approximately 1 hour). The product was subsequently removed from the reactor and freed of volatile components on a rotary evaporator.

[0195] The diblock copolymer thus prepared features the following properties:

[0196] Incorporated CO.sub.2 (% by weight) based on the portion of the polymer that was formed under CO.sub.2: 6.9% by weight;

[0197] The selectivity al was 0.79 and the polydispersity was 1.01.

Example 7: Preparation of a Diblock Copolymer (DBC-5) Using 1-dodecanol as H-Functional Starter Substance

[0198] Step ():

[0199] A 2 liter pressure reactor with gas metering device was initially charged with 163 mg of dried DMC catalyst (prepared according to example 6 of WO-A 01/80994) and 144.88 g of 1-dodecanol.

[0200] The suspension was then heated to 130 C. and a constant nitrogen stream and a reduced pressure of 100 mbar were applied for 30 min.

[0201] Step ():

[0202] The reactor was subsequently charged with 50 bar of CO.sub.2 at 130 C. and 10 g of ethylene oxide were metered into the reactor all at once. Activation of the catalyst was perceptible by a temperature peak (hotspot) and by a pressure drop to the starting pressure (50 bar). The procedure was repeated once more.

[0203] Step ():

[0204] After activation had occurred, the temperature was adjusted to 100 C. and 459.6 g of ethylene oxide were metered into the reactor within 9 h. The progress of the reaction was monitored via the CO.sub.2 consumption, with the pressure in the reactor being held constant at 50 bar by means of continuously controlled further metered addition. After completion of EO addition, stirring was continued at the pressure indicated above until no further consumption of CO.sub.2 was observed (approximately 1 hour). The product was subsequently removed from the reactor and freed of volatile components on a rotary evaporator.

[0205] The diblock copolymer thus prepared features the following properties:

[0206] Incorporated CO.sub.2 (% by weight) based on the portion of the polymer that was formed under CO.sub.2: 8.2% by weight;

[0207] The selectivity al was 1.07 and the polydispersity was 1.01.

TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3* Example 4* Example 5 Example 6 Example 7 Diblock copolymer DBC-1 DBC-2 Lutensol AT Marlipal 24/90 DBC-3 DBC-4 DBC-5 Polydispersity index 1.02 1.03 1.02 1.07 1.03 1.01 1.01 Molecular weight M.sub.n (g/mol) 701 750 735 616 792 762 680 Incorporated CO.sub.2 (% by weight).sup.1) 6.1 5.0 0 0 2.9 6.9 8.2 HLB value 12.9 15.0 12 13.4 16.5 14.9 14.3 Hydrolytic pH 3 degradation at pH 7 25 C. .sup.2) pH 11 Hydrolytic pH 3 x x x x x degradation at pH 7 60 C. .sup.2) pH 11 x x x x x Cloud point 60 C. 88 C. 77 C. 82 C. 76 C. 80 C. 69 C. Temperature dependence of the 32-71 C. 41-72 C. 48-71 C. 49-70 C. 45-80 C. 32-72 C. 45-85 C. emulsification characteristics .sup.1)Incorporated CO.sub.2 (% by weight) based on the portion of the polymer that was formed under CO.sub.2. .sup.2) x: diblock copolymer is hydrolytically degraded, : diblock copolymer is not hydrolytically degraded. *Comparative example

[0208] The results in table 1 show that the diblock copolymers of the inventive process have a high HLB value and at the same time a low PDI. The diblock copolymers from examples 1 to 7 are stable at room temperature in the ranges of pH 3, 7 and 11 and in the neutral pH range are also stable at 60 C. In contrast to the diblock copolymers from comparative examples 3 and 4, however, the diblock copolymers from inventive examples 1, 2 and 5 to 7 can be degraded at 60 C. by the modification of the pH.

[0209] In the case of the diblock copolymer from inventive example 1, there is already formation of the emulsion (third phase) in a temperature range from 32 C. to 71 C. The corresponding diblock copolymer from comparative example 3, which does not comprise any polyethercarbonate-containing block, forms an emulsion in a narrower temperature range from 48 C. to 71 C. The emulsion formed in inventive example 2, with a temperature range from 41 C. to 72 C., is likewise more stable in a broader temperature range than corresponding comparative example 3, with a range from 48 C. to 71 C. The emulsification characteristics of the diblock copolymers obtained with the inventive process are therefore less temperature dependent than in the case of the diblock copolymers from comparative examples 3 and 4. The same applies to the diblock copolymers of examples 5 to 7, which compared to comparative example 4 exhibit a broader temperature range for the formation of the emulsion. The emulsification characteristics of examples 5 to 7 are therefore likewise less temperature dependent than in the case of the diblock copolymer of comparative example 4.

[0210] The zero shear rate viscosities measured for examples 2, 4 and 5 to 7 are given in table 2. The inventive examples have significantly lower zero shear rate viscosities in the water/diblock copolymer mixtures than comparative example 4.

TABLE-US-00002 TABLE 2 Zero shear rate viscosity .sub.0 in Proportion of Pa .Math. s for water/diblock copolymer mixtures diblock copolymer 45% by 50% by 55% by 60% by in the mixture weight weight weight weight Example 2 0.1627 0.2711 0.3262 0.3306 Example 4* 77 890 108 600 35 050 13 690 Example 5 0.2114 0.3961 0.4537 0.5447 Example 6 0.1523 0.2821 0.3094 0.4436 Example 7 0.3359 0.6268 0.7371 0.7083 *Comparative example