CN105384919A - Method for preparing polyester by catalyzing ring-opening polymerization of bis (trifluoromethanesulfonimide) salt - Google Patents

Abstract

The invention discloses a method for preparing polyester by ring-opening polymerization, belonging to the technical field of polymer material synthesis, using cyclic ester as a reaction monomer, bistrifluoromethanesulfonimide salt as a catalyst, and organic alcohol ROH as an initiator , carry out bulk polymerization, and obtain polyester after separation. The invention provides a method for preparing polyester with simple process, low cost and high reaction rate. The method has the advantages of fast reaction, controllable process, mild reaction condition and narrow molecular weight distribution.

Description

Method for preparing polyester by ring-opening polymerization catalyzed by bistrifluoromethanesulfonimide salt

technical field

The invention belongs to the technical field of polymer material synthesis, and refers to a method for preparing polyester by ring-opening polymerization catalyzed by bistrifluoromethanesulfonimide salt.

Background technique

The ring-opening polymerization of cyclic esters is considered to be one of the most controllable methods for the synthesis of aliphatic polyesters. The polymers synthesized by this method have the characteristics of controllable molecular weight and narrow molecular weight distribution. Using different catalytic/initiating systems to realize the ring-opening polymerization of cyclic esters to prepare biodegradable polyesters is an important way to develop environmentally friendly polymers. Biodegradable polyester has the characteristics of recyclability and degradability. It can not only solve the problem of white pollution in plastic applications, but also can promote economic growth while promoting economic growth compared with the large resource consumption and negative environmental impact of traditional industrial polymer materials. Conserve water, energy and raw material consumption while reducing waste emissions. This type of polyester is easy to gradually decompose into oligomers or monomers due to the easily hydrolyzed ester bonds in the polymer, and then further converted into carbon dioxide and water under the action of microorganisms, which can show a certain degree of biocompatibility. This has great application potential in the fields of biomedicine and tissue engineering.

In the past ten years, there have been many studies on the preparation of polyesters using metal compounds. Utilize metal zinc compound (J.Am.Chem.Soc.2003,125,11350-11359; J.Am.Chem.Soc.2001,123,3229-3238), metal aluminum compound (J.Am.Chem. Soc.2003,125,11291-11298) rare earth metal complexes (Angew.Chem.2006,118,2848-2850) prepare polylactide, although these polymerization systems have very high activity, but these catalytic systems are to air and water Highly sensitive and not suitable for industrial production. Among many metal complexes, metallic calcium complexes are more favored by researchers because metallic calcium is cheap and non-toxic. (Chem.Commun.2011, 47, 2276-2278) uses calcium tetrahydroborate complexes to catalyze the ring-opening polymerization of lactide. The preparation process of the catalyst is complicated and requires low temperature treatment.

In this patent, we use bistrifluoromethanesulfonimide salt as a catalyst to catalyze the ring-opening polymerization of cyclic esters. Bistrifluoromethanesulfonimide salt is a substance with good solubility in water and methanol, so there will be no catalyst residue in the process of obtaining the polymer. And this system adopts the method of bulk polymerization, no need to use additional solvent in the reaction system, which is more convenient for industrial production. In the bulk polymerization system, generally higher temperature is used for reaction, which makes the reaction system sensitive to air and water Greatly reduced.

Contents of the invention

The invention provides a method for preparing polyester with simple process, low cost and high reaction rate. The method has the advantages of rapid reaction, controllable process, mild reaction conditions and narrow molecular weight distribution.

Technical scheme of the present invention

The method for preparing polyester by ring-opening polymerization catalyzed by bistrifluoromethanesulfonimide salt provided by the invention uses cyclic ester as a reaction monomer, bistrifluoromethanesulfonimide salt as a catalyst, and organic alcohol ROH as an initiator Agent, bulk polymerization reaction, obtained polyester after separation.

The lactone described in the above method for preparing polyester is butyrolactone, valerolactone, caprolactone; Carbonate is trimethylene carbonate, dimethyl carbonate, diethyl carbonate; Lactide is ethyl lactide, lactide. Wherein the lactone δ-valerolactone, ε-caprolactone; the carbonate is trimethylene carbonate; the lactide is L-lactide. The best lactones are δ-valerolactone and ε-caprolactone; the carbonate is trimethylene carbonate; the lactide is L-lactide.

The bistrifluoromethanesulfonimide salt is calcium bistrifluoromethanesulfonimide, magnesium bistrifluoromethanesulfonimide, lithium bistrifluoromethanesulfonimide, bistrifluoromethanesulfonylimide Aluminum Amine, Zinc Bistrifluoromethanesulfonimide, Copper Bistrifluoromethanesulfonimide, Sodium Bistrifluoromethanesulfonimide, Potassium Bistrifluoromethanesulfonimide. The most preferred is calcium bistrifluoromethanesulfonimide.

The organic alcohol ROH, wherein R is an alkyl group or a phenyl group. The said alkyl group is straight chain, branched chain or cyclic chain having 1 to 22 carbon atoms. Described organic alcohol is methanol, ethanol, pentaerythritol, butynol, phenylpropanol, benzyl alcohol. The most preferred organic alcohol is benzyl alcohol.

The reaction temperature of the method is 40-120°C, the reaction time is 1-24 hours, and the molar ratio of the monomer, bistrifluoromethanesulfonimide salt, and organic alcohol is (30:1:1)～ (200:1:1).

In the above method for preparing polyester, the general structural formula of the monomer L-lactide is:

The structural general formula of described monomer trimethylene carbonate is:

The structural general formula of described monomer δ-valerolactone is:

The general structural formula of the monomer ε-caprolactone is:

The general structural formula of the calcium salt of described two trifluoromethanesulfonimides is:

The structural general formula of described poly L-lactide is:

The general structural formula of described polytrimethylene carbonate is:

The structural general formula of described polyvalerolactone is:

The structural general formula of described polycaprolactone is:

Wherein n, m, x, y represent different degrees of polymerization respectively, for example: if the reacted lactide in the monomer fed is 1, then n=1, if the reacted lactide in the monomer fed is There are 2 lactides, then n=2...and so on. The same goes for m,x,y.

In the preparation method of the polyester, the structure of the polymer is identified by hydrogen spectroscopy, and the molecular weight and dispersion properties of the polymer are determined by size exclusion chromatography.

In the preparation method of L-polylactide, the molar ratio of monomer L-lactide, bistrifluoromethanesulfonimide calcium, benzyl alcohol is (30:1:1)～(200:1: 1). The reaction temperature is 120° C., and the reaction time is 1 to 24 hours. After the reaction is over, polylactide is obtained.

In the preparation method of polytrimethylene carbonate, the molar ratio of monomer trimethylene carbonate, bistrifluoromethanesulfonimide calcium, benzyl alcohol is (30:1:1)～(200:1 : 1). The bulk reaction temperature of polytrimethylene carbonate is 60° C., and the reaction time is 1 to 24 hours. After the reaction, polytrimethylene carbonate was obtained.

In the preparation method of polyvalerolactone, the molar ratio of monomer δ-valerolactone, bistrifluoromethanesulfonimide calcium, benzyl alcohol is (30:1:1)～(200:1:1 ). The bulk reaction temperature of polyvalerolactone is 120° C., and the reaction time is 1 to 24 hours. After the reaction ends, polyvalerolactone is obtained.

In the preparation method of polycaprolactone, the molar ratio of monomer ε-caprolactone, bistrifluoromethanesulfonimide calcium, benzyl alcohol is (30:1:1)～(200:1:1 ). The bulk reaction temperature of the polycaprolactone is 120° C., and the reaction time is 1 to 24 hours. After the reaction is over, polycaprolactone is obtained.

Beneficial effects of the present invention

1. Using bistrifluoromethanesulfonimide calcium catalyst system, compared with the metal residues brought by metal catalysts such as organotin salts, organozinc salts and organoaluminum salts, it is determined to obtain better cytotoxicity. The solution is that the synthesized polyester has higher biological safety and can be better applied in the field of medical materials.

2. This process can control the synthesis of target molecular weight product polyester according to the demand, the product yield is high, there is no monomer residue, and the color is white.

3. The polymerization method of bulk polymerization is adopted, and no additional solvent needs to be added in the reaction system, which is convenient for industrial production.

Description of drawings

Figure 1. Preparation method of poly-L-lactide

Figure 2. Preparation method of polytrimethylene carbonate

Figure 3. Hydrogen spectrum of polylactide

Figure 4. Hydrogen spectrum of polytrimethylene carbonate

detailed description

The technical solutions of the present invention are described below with specific examples, but the protection scope of the present invention is not limited thereto. L-lactide is used as an example for lactide; trimethylene carbonate is used as an example for carbonate; δ-valerolactone and ε-caprolactone are used as examples for lactone.

Example 1

In a 10ml polymerization tube, add L-lactide (0.432g, 3mmol), calcium bistrifluoromethanesulfonimide (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), at 120°C Stir mechanically under the conditions for 24 hours. After the reaction is completed, the reaction is terminated. The obtained crude product is slowly dropped into cold methanol, and a polymer is precipitated. The polymer is obtained by centrifugal drying, and finally identified by hydrogen spectrum.

Example 2

In a 10ml polymerization tube, add L-lactide (0.720g, 5mmol), calcium bistrifluoromethanesulfonyl imide (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), at 120°C Under the condition of mechanical stirring for 24 hours, after the reaction was finished, the reaction was terminated, and the obtained crude product was slowly dropped into cold methanol, and a polymer was precipitated, and the polymer was obtained by centrifugal drying, and finally identified by hydrogen spectrum (accompanying drawing 3).

Example 3

In a 10ml polymerization tube, add L-lactide (2.880g, 20mmol), calcium bistrifluoromethanesulfonyl imide (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), at 120°C Stir mechanically under the conditions for 24 hours. After the reaction is completed, the reaction is terminated. The obtained crude product is slowly dropped into cold methanol, and a polymer is precipitated. The polymer is obtained by centrifugal drying, and finally identified by hydrogen spectrum.

Example 4

In a 10ml polymerization tube, add trimethylene carbonate (0.306g, 3mmol), bistrifluoromethanesulfonimide calcium (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), at 50°C Stir mechanically under the conditions for 24 hours. After the reaction is completed, the reaction is terminated. The obtained crude product is slowly dropped into cold methanol, and a polymer is precipitated. The polymer is obtained by centrifugal drying, and finally identified by hydrogen spectrum.

Example 5

In a 10ml polymerization tube, add trimethylene carbonate (0.510g, 5mmol), bistrifluoromethanesulfonimide calcium (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), at 50°C Under the condition of mechanical stirring for 24 hours, after the reaction was finished, the reaction was terminated, and the obtained crude product was slowly dropped into cold methanol, and a polymer was precipitated, and the polymer was obtained by centrifugal drying, which was finally identified by hydrogen spectrum (accompanying drawing 4).

Example 6

In a 10ml polymerization tube, add trimethylene carbonate (2.040g, 20mmol), bistrifluoromethanesulfonimide calcium (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), at 50°C Stir mechanically under the conditions for 24 hours. After the reaction is completed, the reaction is terminated. The obtained crude product is slowly dropped into cold methanol, and a polymer is precipitated. The polymer is obtained by centrifugal drying, and finally identified by hydrogen spectrum.

Example 7

In a 10ml polymerization tube, add δ-valerolactone (270μL, 3mmol), calcium bistrifluoromethanesulfonimide (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), and set After the reaction was completed, the reaction was terminated, and the obtained crude product was slowly dropped into cold methanol, and a polymer was precipitated, and the polymer was obtained by centrifugal drying, which was finally identified by hydrogen spectrum.

Example 8

In a 10ml polymerization tube, add δ-valerolactone (450μL, 5mmol), calcium bistrifluoromethanesulfonimide (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), and condition After the reaction was completed, the reaction was terminated, and the obtained crude product was slowly dropped into cold methanol, and a polymer was precipitated, and the polymer was obtained by centrifugal drying, which was finally identified by hydrogen spectrum.

Example 9

In a 10ml polymerization tube, add δ-valerolactone (1.80mL, 20mmol), calcium bistrifluoromethanesulfonimide (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 1mmol), and condition After the reaction was completed, the reaction was terminated, and the obtained crude product was slowly dropped into cold methanol, and a polymer was precipitated, and the polymer was obtained by centrifugal drying, which was finally identified by hydrogen spectrum.

Example 10

In a 10ml polymerization tube, add ε-caprolactone (318.3μL, 3mmol), bistrifluoromethanesulfonimide calcium (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), at 80°C Stir mechanically under the conditions for 24 hours. After the reaction is completed, the reaction is terminated. The obtained crude product is slowly dropped into cold methanol, and a polymer is precipitated. The polymer is obtained by centrifugal drying, and finally identified by hydrogen spectrum.

Example 11

In a 10ml polymerization tube, add ε-caprolactone (530.5μL, 5mmol), bistrifluoromethanesulfonimide calcium (0.053g, 1.0mmol), benzyl alcohol (10.3μL, 1mmol), and condition After the reaction was completed, the reaction was terminated, and the obtained crude product was slowly dropped into cold methanol, and a polymer was precipitated, and the polymer was obtained by centrifugal drying, which was finally identified by hydrogen spectrum.

Example 10

In a 10ml polymerization tube, add ε-caprolactone (2.12mL, 20mmol), bistrifluoromethanesulfonimide calcium (0.053g, 0.1mmol), benzyl alcohol (10.3μL, 0.1mmol), at 80°C Stir mechanically under the conditions for 24 hours. After the reaction is completed, the reaction is terminated. The obtained crude product is slowly dropped into cold methanol, and a polymer is precipitated. The polymer is obtained by centrifugal drying, and finally identified by hydrogen spectrum.

Claims (8)

1. a method for polyester is prepared in ring-opening polymerization, it is characterized in that: utilize cyclic ester as reaction monomers, and two fluoroform sulfimide salt, as catalyzer, utilizes organic alcohol roh as initiator, carries out bulk polymerization and obtains polyester.

2. prepare the method for polyester as claimed in claim 1, it is characterized in that, described cyclic ester comprises lactone, carbonic ether, lactide.

3. prepare the method for polyester as claimed in claim 2, it is characterized in that, described lactone is butyrolactone, valerolactone, caprolactone; Described carbonic ether is trimethylene carbonate, dimethyl carbonate, diethyl carbonate; Described lactide is glycollide, rac-Lactide.

4. prepare the method for polyester as claimed in claim 3, it is characterized in that, described lactone is δ-valerolactone, 6-caprolactone; Described carbonic ether is trimethylene carbonate; Described lactide is L-rac-Lactide.

5. prepare the method for polyester as claimed in claim 1, it is characterized in that, the R in described organic alcohol roh is alkyl or phenyl, and described alkyl is have the straight chain of 1 to 22 carbon atom, side chain or closed chain.

6. prepare the method for polyester as claimed in claim 5, it is characterized in that, described Organic Alcohol is methyl alcohol, ethanol, tetramethylolmethane, butynol, phenylpropyl alcohol, phenylcarbinol.

7. the method preparing polyester as described in claim 1 to 6 any one, it is characterized in that, described two fluoroform sulfimide salt are two fluoroform sulfimide calcium, two fluoroform sulfimide magnesium, two fluoroform sulfimide lithium, two fluoroform sulfimide aluminium, two fluoroform sulfimide zinc, two fluoroform sulfimide copper, two fluoroform sulfimide sodium, two fluoroform sulfimide potassium.

8. the method preparing polyester as described in claim 1 to 6 any one, it is characterized in that, described method temperature of reaction is 40 ~ 120 DEG C, reaction times is 1 ~ 24 hour, and the mol ratio of described monomer, two fluoroform sulfimide salt, Organic Alcohol is (30: 1: 1) ~ (200: 1: 1).