Polymerization method of polycaprolactone

Abstract

The invention discloses a polymerization method of polycaprolactone, which comprises the following steps: by taking epsilon-caprolactone as a monomer and acetylacetone salt as a catalyst, adding an initiator, preparing polycaprolactone by adopting a bulk polymerization method under the conditions that the reaction temperature is 130-150 DEG C and the reaction time is 4-48 hours, and washing, precipitating and drying in vacuum to obtain the polycaprolactone, according to the technical scheme provided by the invention, acetylacetonate is used as a catalyst for polymerization preparation of epsilon-caprolactone, and the method has the advantages of high catalytic activity, mild conditions, simple process and the like.

Description

Technical Field

[0001] The present invention belongs to the field of synthesis technology, and particularly relates to a polymerization method of polycaprolactone. Background Art

[0002] Polycaprolactone is a biodegradable polymer with good mechanical properties, flexibility and biocompatibility. Therefore, it has a wide range of applications in many fields, such as manufacturing surgical sutures, scaffolds, biomedical materials and implants, bandages and dressings, etc.

[0003] At present, the synthesis of polycaprolactone is mainly catalyzed by Lewis acids or metal complexes, such as boron trifluoride, aluminum chloride, zinc oxide, etc., to achieve ring-opening polymerization of caprolactone under bulk conditions. Enzyme catalysts have high costs, harsh reaction conditions and side reactions during the reaction, which bring difficulties and challenges to subsequent production. Seeking a catalyst with high activity, low cost and simple reaction conditions has become a hot topic in the current field.

[0004] Chinese Patent CN202310432289.3 discloses a method for preparing polycaprolactone by metal trifluoromethanesulfonate catalysis, but the production of trifluoromethanesulfonic acid required for the reaction is complex and costly, and the reaction conditions are sensitive and easily deactivated. Chinese Patent CN201710081585.8 discloses a method for preparing polycaprolactone by metal halide catalysis, but it is difficult to separate and recycle the catalyst after the reaction, and metal halides will cause certain pollution to the environment.

[0005] Therefore, the current process for catalytic preparation of polycaprolactone still has deficiencies. Developing a polymerization method of polycaprolactone with fewer side reactions, high selectivity, and thus ensuring high purity of the reaction product is of great significance. Summary of the Invention

[0006] Aiming at the above deficiencies, the purpose of the present invention is to provide a polymerization method of polycaprolactone with high catalytic activity, few side reactions, high selectivity, mild conditions and simple process.

[0007] To this end, the first technical solution provided by the present invention is as follows:

[0008] A polymerization method of polycaprolactone, using ε-caprolactone as a monomer, acetylacetonate as a catalyst, adding an initiator, and under the conditions of a reaction temperature of 130 - 150 °C and a reaction time of 4 - 48 hours, polycaprolactone is prepared by bulk polymerization, and polycaprolactone is obtained through washing, precipitation and vacuum drying;

[0009] The molar ratio of the monomer to the initiator is 200 - 2000:1;

[0010] The molar ratio of the initiator to the catalyst is 1 - 5:1.

[0011] Further, in the above polymerization method of polycaprolactone, the initiator is one or any combination of butanediol, ethylene glycol, glycerol, PPG400, PEG400, and hexamethylenediamine.

[0012] Further, in the above polymerization method of polycaprolactone, the acetylacetonate is one of iron acetylacetonate, aluminum acetylacetonate, copper acetylacetonate, silver acetylacetonate, zinc acetylacetonate, tin acetylacetonate, nickel acetylacetonate, and lead acetylacetonate.

[0013] Further, in the above polymerization method of polycaprolactone, the molar ratio of the monomer to the initiator is 800 - 1500:1.

[0014] Further, in the above polymerization method of polycaprolactone, the molar ratio of the initiator to the catalyst is 2 - 4:1.

[0015] Further, in the above polymerization method of polycaprolactone, the reaction temperature is 135 - 140 °C.

[0016] Another object of the present invention is to provide a polycaprolactone obtained by polymerizing according to the polymerization method described in the first technical solution.

[0017] The polycaprolactone has a molecular weight of 50,000 - 80,000; the dispersity is 1.3 - 1.8.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) The method of the present invention has few side reactions and high selectivity, which can ensure the high purity of the reaction product, facilitating the subsequent separation and purification processes. This not only helps to improve the product quality but also reduces the production cost and improves the production efficiency.

[0020] 2) The polycaprolactone obtained by the technical solution provided by the present invention has a uniform molecular weight distribution, with a dispersity between 1.3 and 1.8 and a weight - average molecular weight in the range of 50,000 - 80,000, meeting the requirements for the molecular weight and distribution of polycaprolactone in practical applications. Description of the Drawings

[0021] Figure 1 is the infrared spectrum of the polycaprolactone prepared in Example 1;

[0022] Figure 2 is the nuclear magnetic resonance H spectrum of the polycaprolactone prepared in Example 1;

[0023] Figure 3 is the nuclear magnetic resonance C spectrum of the polycaprolactone prepared in Example 1; Detailed Embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Example 1

[0026] Using ε-caprolactone as the monomer, adding butanediol as the initiator and aluminum acetylacetonate as the catalyst, the molar ratio of the monomer to the initiator is 1000:1, and the molar ratio of the initiator to the catalyst is 3:1. At a reaction temperature of 140 °C and a reaction time of 48 hours, a crude polycaprolactone product is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 70,000, a dispersity (PDI) of 1.3, and a caprolactone conversion rate of 99.8%.

[0027] The infrared spectrum of the polycaprolactone prepared in Example 1 is referred to Figure 1 , and the nuclear magnetic resonance H spectrum is referred to Figure 2 , and the nuclear magnetic resonance C spectrum is referred to Figure 3 .

[0028] Example 2

[0029] Using ε-caprolactone as the monomer, adding ethylene glycol as the initiator and aluminum acetylacetonate catalyst, the molar ratio of the monomer to the initiator is 500:1, and the molar ratio of the initiator to the catalyst is 1:1. At a reaction temperature of 130 °C and a reaction time of 36 hours, a crude polycaprolactone product is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 66,000, a dispersity (PDI) of 1.4, and a caprolactone conversion rate of 99.9%.

[0030] Example 3

[0031] Using ε-caprolactone as the monomer, adding glycerol as the initiator and aluminum acetylacetonate catalyst, the molar ratio of the monomer to the initiator is 800:1, and the molar ratio of the initiator to the catalyst is 5:1. At a reaction temperature of 140 °C and a reaction time of 4 hours, a crude polycaprolactone product is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 80,000, a dispersity (PDI) of 1.5, and a caprolactone conversion rate of 99.7%.

[0032] Example 4

[0033] Using ε-caprolactone as the monomer, adding initiator PPG400 and zinc acetylacetonate catalyst, the molar ratio of the monomer to the initiator is 2000:1, and the molar ratio of the initiator to the catalyst is 4:1. At a reaction temperature of 150 °C and a reaction time of 48 hours, the crude polycaprolactone is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 80000, a dispersity (PDI) of 1.4, and a caprolactone conversion rate of 99.0%.

[0034] Example 5

[0035] Using ε-caprolactone as the monomer, adding initiator PPG1000 and iron acetylacetonate catalyst, the molar ratio of the monomer to the initiator is 1000:1, and the molar ratio of the initiator to the catalyst is 3:1. At a reaction temperature of 140 °C and a reaction time of 18 hours, the crude polycaprolactone is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 50000, a dispersity (PDI) of 1.6, and a caprolactone conversion rate of 99.4%.

[0036] Example 6

[0037] Using ε-caprolactone as the monomer, adding initiator hexanediol and copper acetylacetonate catalyst, the molar ratio of the monomer to the initiator is 1500:1, and the molar ratio of the initiator to the catalyst is 2:1. At a reaction temperature of 135 °C and a reaction time of 48 hours, the crude polycaprolactone is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 57000, a dispersity (PDI) of 1.8, and a caprolactone conversion rate of 99.5%.

[0038] Example 7

[0039] Using ε-caprolactone as the monomer, adding initiator diethylene glycol and tin acetylacetonate catalyst, the molar ratio of the monomer to the initiator is 1200:1, and the molar ratio of the initiator to the catalyst is 4:1. At a reaction temperature of 140 °C and a reaction time of 32 hours, the crude polycaprolactone is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 62000, a dispersity (PDI) of 1.3, and a caprolactone conversion rate of 99.4%.

[0040] Example 8

[0041] Using ε-caprolactone as the monomer, adding hexamethylenediamine as the initiator and silver acetylacetonate as the catalyst, the molar ratio of the monomer to the initiator is 800:1, and the molar ratio of the initiator to the catalyst is 3:1. At a reaction temperature of 140 °C and a reaction time of 24 hours, a crude polycaprolactone product is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 52000, a dispersity (PDI) of 1.5, and a caprolactone conversion rate of 99.2%.

[0042] Example 9

[0043] Using ε-caprolactone as the monomer, adding PEG400 as the initiator and iron acetylacetonate as the catalyst, the molar ratio of the monomer to the initiator is 1000:1, and the molar ratio of the initiator to the catalyst is 3:1. At a reaction temperature of 140 °C and a reaction time of 12 hours, a crude polycaprolactone product is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 70000, a dispersity (PDI) of 1.3, and a caprolactone conversion rate of 100%.

[0044] Example 10

[0045] Using ε-caprolactone as the monomer, adding PEG2000 as the initiator and aluminum acetylacetonate as the catalyst, the molar ratio of the monomer to the initiator is 500:1, and the molar ratio of the initiator to the catalyst is 4:1. At a reaction temperature of 140 °C and a reaction time of 12 hours, a crude polycaprolactone product is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 66000, a dispersity (PDI) of 1.3, and a caprolactone conversion rate of 99.3%.

[0046] Example 11

[0047] Using ε-caprolactone as the monomer, adding butanediol as the initiator and lead acetylacetonate as the catalyst, the molar ratio of the monomer to the initiator is 1000:1, and the molar ratio of the initiator to the catalyst is 3:1. At a reaction temperature of 140 °C and a reaction time of 16 hours, a crude polycaprolactone product is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is measured by gel permeation chromatography (GPC) to have a weight-average molecular weight (M) of 51000, a dispersity (PDI) of 1.3, and a caprolactone conversion rate of 99.0%.

[0048] Example 12

[0049] Using ε-caprolactone as the monomer, adding initiator 1,4-butanediol and nickel acetylacetonate catalyst, the molar ratio of the monomer to the initiator is 200:1, the molar ratio of the initiator to the catalyst is 1:1. At a reaction temperature of 140 °C and a reaction time of 42 hours, the crude polycaprolactone is obtained. It is washed three times with absolute ethanol, the precipitate is collected, and dried at 0.1 KPa and 60 °C for 3 h to obtain polycaprolactone. The product is determined by gel permeation chromatography (GPC) to have a weight-average molecular weight (Mw) of 70,000, a polydispersity index (PDI) of 1.3, and a caprolactone conversion rate of 99.6%.

Claims

1. A method for the polymerization of polycaprolactone, characterized in that: Using ε-caprolactone as a monomer, acetylacetonate as a catalyst, adding an initiator, and preparing polycaprolactone by bulk polymerization at a reaction temperature of 130 to 150° C. and a reaction time of 4 to 48 hours, and then washing, precipitating and vacuum drying to obtain polycaprolactone; The molar ratio of the monomer to the initiator is 200 to 2000:1; The molar ratio of the initiator to the catalyst is 1 to 5:

1.

2. The method for polymerizing polycaprolactone according to claim 1, characterized in that: The initiator is one of butanediol, ethylene glycol, glycerol, PPG400, PEG400, hexamethylenediamine or any combination thereof.

3. The method for polymerizing polycaprolactone according to claim 1, characterized in that: The acetylacetonate is one of iron acetylacetonate, aluminum acetylacetonate, copper acetylacetonate, silver acetylacetonate, zinc acetylacetonate, tin acetylacetonate, nickel acetylacetonate and lead acetylacetonate.

4. The method for polymerizing polycaprolactone according to claim 1, characterized in that: The molar ratio of the monomer to the initiator is 800-1500:

1.

5. The method for polymerizing polycaprolactone according to claim 1, characterized in that: The molar ratio of the initiator to the catalyst is 2-4:

1.

6. The method for polymerizing polycaprolactone according to claim 1, characterized in that: The reaction temperature is 135-140°C.

7. A polycaprolactone, characterized in that: Obtained by the polymerization method described in any one of claims 1 to 6.

8. The polycaprolactone according to claim 7, characterized in that: The molecular weight of the polycaprolactone is 50,000-80,000.

9. The polycaprolactone according to claim 7, characterized in that: The dispersion degree of the polycaprolactone is 1.3-1.8.

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