Method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation and its product

Abstract

The invention discloses a method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonate activation, wherein rare earth trifluoromethanesulfonate is used as an activator, polytetrahydrofuran containing terminal hydroxyl groups is used as an initiator, and ring-opening polymerization of α-amino acid-N-carboxylic anhydride is activated and initiated in an organic solvent to prepare polytetrahydrofuran-polyamino acid block copolymer. The method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonate activation disclosed by the invention directly prepares polytetrahydrofuran-polyamino acid block copolymer by a one-step method, and has high initiation efficiency and strong controllability; the prepared copolymer has adjustable molecular weight, variable composition, and narrow molecular weight distribution; in addition to preparing diblock copolymers and triblock copolymers, star-shaped block copolymers can also be prepared.

Description

Technical Field

[0001] The invention relates to the technical field of high molecular polymers, and in particular to a method for preparing polytetrahydrofuran-polyamino acid block copolymers by rare earth activation with trifluoromethanesulfonic acid and a product thereof. Background Art

[0002] Poly (amino acid) is a synthetic polymer with amino acid residues as the main chain structure, similar composition and properties to proteins, and good biocompatibility and degradability. The properties of poly (amino acid) can vary with the side groups, such as stimulus responsiveness, hydrophilicity or autocatalysis. It has broad prospects in the fields of engineering materials and biomedical fields such as drug delivery, biosensors, and tissue engineering, so it has attracted much attention (Prog. Polym. Sci., 2014, 39, 330-364). At present, the α-amino acid-N-carboxylic anhydride (NCA) ring-opening polymerization method is the most commonly used method for the controllable synthesis of poly (amino acid) (Chem. Soc. Rev., 2013, 42, 7373-7390).

[0003] Polytetrahydrofuran is a polymer obtained by cationic ring-opening polymerization of tetrahydrofuran. It is one of the important raw materials used to adjust the flexibility of spandex, polyurethane, and polyetherester elastomer materials. Polytetrahydrofuran has good flexibility, hydrolysis resistance, antibacterial, good biocompatibility, and stable chemical properties. Due to its unique properties, polytetrahydrofuran has broad application prospects in the fields of textiles, medical treatment, engineering, etc., especially in the preparation of high-performance elastic materials. It plays a pivotal role (Fine Chemical Raw Materials and Intermediates, 2008, 3, 34-37).

[0004] Polyamino acids can form secondary structures such as random coils, α-helices, and β-folds, so materials based on polyamino acids have good mechanical strength. The main chain of polytetrahydrofuran has good flexibility, and the block copolymers of the two can be used to prepare elastomers with polyamino acids as hard segments and polytetrahydrofuran as soft segments. The hydrophilicity of polyamino acids and the hydrophobicity of polytetrahydrofuran can also be used to prepare amphiphilic block copolymers to provide carriers for drug delivery. The synthesis of this polyether polyamino acid copolymer has important research and application value.

[0005] NCA is usually polymerized by amino groups, but commercially available polytetrahydrofuran only carries hydroxyl groups but does not contain amino groups. In order to obtain polytetrahydrofuran-polyamino acid block copolymers, Ling et al. designed a method to introduce amino groups into the ends of polytetrahydrofuran chains, that is, using a terminator to in situ convert the terminal oxonium ions of polytetrahydrofuran into protected amino groups during the polymerization of tetrahydrofuran, and then obtaining amino-terminated polytetrahydrofuran after deprotection. Subsequently, the macromolecular initiator was used to initiate polymerization to obtain polytetrahydrofuran-polyamino acid diblock copolymers (ZL 201911376690.X). This type of diblock copolymer can form micelles in aqueous solution or be used to stabilize water / oil emulsions, and has application prospects in the field of drug delivery. In addition, they also tried to convert the terminal hydroxyl groups of polytetrahydrofuran into oxyamine groups for the preparation of triblock polytetrahydrofuran-polyamino acid block copolymers. The micelles formed by these block copolymers can respond to chain scission under acidic conditions, and therefore can play a role in the fields of controlled drug release and precision medicine (Chin. J. Chem., 2021, 39, 2852-2856). However, the synthesis of these block copolymers requires end group conversion, which is cumbersome and requires many steps. The purification process in the intermediate steps will lead to the loss and waste of raw materials, lack of atom economy, and increase the difficulty of industrial production. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention discloses a method for preparing a polytetrahydrofuran-polyamino acid block copolymer by rare earth activation with trifluoromethanesulfonic acid. The polytetrahydrofuran-polyamino acid block copolymer is directly prepared by a one-step method, and the initiation efficiency is high and the controllability is strong. The prepared copolymer has an adjustable molecular weight, a variable composition and a narrow molecular weight distribution. In addition to preparing diblock copolymers and triblock copolymers, star-shaped block copolymers can also be prepared.

[0007] The specific technical solutions are as follows:

[0008] The invention discloses a method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonate activation. The method comprises taking rare earth trifluoromethanesulfonate as an activator and polytetrahydrofuran containing terminal hydroxyl groups as an initiator, activating and initiating the ring-opening polymerization of alpha-amino acid-N-carboxylic anhydride in an organic solvent, and preparing the polytetrahydrofuran-polyamino acid block copolymer.

[0009] The present invention aims at the problems in the prior art that the polymerization efficiency of α-amino acid-N-carboxylic anhydride directly initiated by the terminal hydroxyl group of polytetrahydrofuran is low, polytetrahydrofuran that has not initiated polymerization will remain in the system (the residue is difficult to separate and remove from the polytetrahydrofuran-polyamino acid block copolymer), and the polymerization reaction is uncontrollable. For the first time, it is proposed to use rare earth trifluoromethanesulfonate as an activator, and the rare earth element is coordinated with the terminal hydroxyl group of polytetrahydrofuran to activate the hydroxyl group, thereby initiating the polymerization of α-amino acid-N-carboxylic anhydride. According to experiments, the method can directly prepare polytetrahydrofuran-polyamino acid block copolymer by a one-step method, with high initiation efficiency, and no residual polytetrahydrofuran is detected in the product; the controllability is extremely strong, and the molecular weight of the product is close to the theoretical value, so the molecular weight of the product can be accurately regulated by regulating the feed ratio of the raw materials; and the molecular weight distribution of the product is narrow.

[0010] The structural formula of the rare earth trifluoromethanesulfonate is RE(OSO2CF3)3;

[0011] RE represents a rare earth element, which is selected from one or more of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.

[0012] The method disclosed in the present invention has good universality, and the rare earth trifluoromethanesulfonate composed of the rare earth elements listed above has good activation performance for the hydroxyl-terminated polytetrahydrofuran in the present invention.

[0013] The polytetrahydrofuran containing terminal hydroxyl groups has a structural formula as shown in the following formula (I) or the following formula (II):

[0014]

[0015] R 1 With R 2 independently selected from hydrogen or a group inert to the ring-opening polymerization of α-amino acid-N-carboxylic anhydride;

[0016] m is a natural number selected from 1 to 4;

[0017] n1 and n2 represent the number of repeating units and are positively correlated with the number average molecular weight of the polytetrahydrofuran containing terminal hydroxyl groups.

[0018] R 1 With R 2 The group does not participate in the reaction, so in addition to H, a group that is inert to the ring-opening polymerization of α-amino acid-N-carboxylic anhydride can also be selected, and the specific group can be selected from the types of groups that meet the above conditions known in the art, without special requirements.

[0019] Specifically:

[0020] R 1 With R 2Independently selected from one or more of hydrogen, C1-C12 saturated aliphatic hydrocarbon groups, halogen-substituted C1-C12 saturated aliphatic hydrocarbon groups, C1-C12 unsaturated aliphatic hydrocarbon groups, halogen-substituted C1-C12 unsaturated aliphatic hydrocarbon groups, and aromatic hydrocarbon groups.

[0021] The aromatic hydrocarbon group is selected from 4-methylene-phenyl and / or 4-methylene-biphenyl.

[0022] In formula (I), when R 1 When H is selected, it is polytetrahydrofuran with double terminal hydroxyl groups; the final product prepared by activating it is a triblock copolymer.

[0023] When R 1 When the group is selected from the group inert to the ring-opening polymerization of α-amino acid-N-carboxylic anhydride, such as the above-mentioned saturated or unsaturated aliphatic hydrocarbon group with or without halogen substitution, aromatic hydrocarbon group, etc., it is polytetrahydrofuran with one terminal hydroxyl group; the final product prepared by activating it is a diblock copolymer.

[0024] In formula (II), m is selected from a natural number of 1 to 4, but the specific value depends on R 2 Groups, exemplified by the following:

[0025] When R 2 When selected from H or -CH3, m = 1; when R 2 When selected from -CH2-, m = 2; when R 2 Selected from When m=3, when R 2 Selected from When m is selected from 3 or 4, the final product prepared by activating the same is a star-shaped block copolymer.

[0026] Formula (II) can be selected from 2,2′-[[2-ethyl-2-[(oxiranylmethoxy)methyl]-1,3-dipropyl]bis(oxymethylene)] three-arm polytetrahydrofuran (m=3), the structural formula of which is as follows:

[0027]

[0028] Or 3,3-di(2-ethoxy)-1,5-pentanediether four-arm polytetrahydrofuran (m=4), the structural formula is as follows:

[0029]

[0030] n3 and n4 represent the number of repeating units.

[0031] Preferably, the number average molecular weight of the polytetrahydrofuran containing terminal hydroxyl groups is 1000-10000 g / mol. It has been found through experiments that the use of the above number average molecular weight can ensure high activity of the terminal hydroxyl groups in the polytetrahydrofuran chain during the polymerization process.

[0032] The α-amino acid-N-carboxylic anhydride has a structural formula as shown in the following formula (III):

[0033]

[0034] In the formula, R 3 , R 4 Independently selected from hydrogen, C1~C9 saturated aliphatic hydrocarbon group, C1~C9 unsaturated aliphatic hydrocarbon group, aromatic hydrocarbon group, C1~C6 carboxyalkyl group with protected carboxyl group (such as -R-COOR), and C1~C6 aminoalkyl group with protected amino group (such as R-NH-Prot).

[0035] Specifically, it can be selected from one or more of ε-benzyloxycarbonyllysine NCA, ε-trifluoroacetyllysine NCA, γ-methylglutamate NCA, γ-ethylglutamate NCA, γ-benzylglutamate NCA, β-benzylaspartate NCA, methionine NCA, alanine NCA, phenylalanine NCA, leucine NCA, isoleucine NCA, valine NCA, glycine NCA, sarcosine NCA, and N-substituted glycine NCA.

[0036] ε-Benzyloxycarbonyllysine NCA

[0037] ε-Trifluoroacetyl lysine NCA

[0038] γ-Methyl-Glutamate NCA

[0039] γ-Ethyl Glutamate NCA γ-Benzyl Glutamate NCA β-Benzyl Aspartate NCA Methionine NCA

[0040] Alanine NCA

[0041] Phenylalanine NCA

[0042] Leucine NCA

[0043] Isoleucine NCA

[0044] Valine NCA

[0045] Glycine NCA

[0046] Sarcosine NCA

[0047] N-substituted glycine NCA

[0048] (R 5 Selected from C2-C9 saturated aliphatic hydrocarbon group, C2-C9 unsaturated aliphatic hydrocarbon group, aromatic hydrocarbon group, C1-C6 carboxyalkyl group with protected carboxyl group, C1-C6 aminoalkyl group with protected amino group)

[0049] The selection of the organic solvent is very important, and it needs to be a good solvent for polytetrahydrofuran, α-amino acid-N-carboxylic anhydride monomer and polymerization product. It is preferably selected from one or more of tetrahydrofuran, methyltetrahydrofuran, dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, dimethyl sulfoxide, cyclopentane, nitrobenzene, benzonitrile, N-methylpyrrolidone, toluene, dichloromethane and chloroform. It has been found through experiments that the use of a preferred organic solvent can ensure the equal activity of the terminal hydroxyl groups in the polytetrahydrofuran chain during the polymerization process.

[0050] In the reaction system, the concentration of α-amino acid-N-carboxylic anhydride is 0.1-2 mmol / mL, where the concentration is calculated based on the total volume of all raw materials (including organic solvent, initiator, activator and monomer) in the reaction system.

[0051] The molar ratio of α-amino acid-N-carboxylic anhydride to the hydroxyl group in the initiator is 10 to 500:1, preferably 10 to 100:1.

[0052] The molar ratio of the activator to the hydroxyl group in the initiator is 0.01 to 100:1, preferably 0.5 to 10:1.

[0053] The temperature of the ring-opening polymerization is -10 to 100° C., and the time is 1 hour to 10 days.

[0054] The present invention also discloses a polytetrahydrofuran-polyamino acid block copolymer prepared according to the above method, wherein the number average molecular weight range is adjustable, about 2000-80000 g / mol; the molecular weight distribution of the product is narrow, and PDI is less than 1.40; and in the copolymer, the ratio of the tetrahydrofuran block to the amino acid block can be adjusted, and a diblock copolymer, a triblock copolymer and a star-shaped block copolymer can be prepared.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The invention discloses a one-step method for preparing a polytetrahydrofuran-polyamino acid block copolymer. The method uses rare earth trifluoromethanesulfonate as an activator and polytetrahydrofuran containing terminal hydroxyl groups as an initiator. The method has high initiation efficiency and no polytetrahydrofuran residue is detected in the product. The method has extremely strong controllability and a narrow molecular weight distribution of the copolymerization product. The proportion of the polyamino acid segment in the copolymer can be regulated by adjusting the ratio of the monomer to the terminal hydroxyl polytetrahydrofuran. The prepared polytetrahydrofuran-polyamino acid block copolymer has good degradability and biocompatibility, can form assemblies such as vesicles, micelles and emulsions, and has great application prospects in the biomedical field and chemical production. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is the H NMR spectrum of the product prepared in Comparative Example 1;

[0058] Figure 2 This is the H NMR spectrum of the product prepared in Example 1. DETAILED DESCRIPTION

[0059] The present invention is further described in detail below in conjunction with examples and comparative examples, but the embodiments of the present invention are not limited thereto.

[0060] The molecular weight and structure of polytetrahydrofuran-polyamino acid block copolymers were determined by gel permeation chromatography (SEC) and nuclear magnetic resonance spectroscopy ( 1 H NMR) determination.

[0061] Molecular weight and molecular weight distribution were determined in SEC (Waters 2414) (hexafluoroisopropanol as mobile phase, 35° C., flow rate 0.8 mL / min).

[0062] The NMR spectra were measured on a Bruker Avance DMX 400 instrument using deuterated dimethyl sulfoxide (DMSO-d6) or deuterated chloroform (CDCl3) as solvent and tetramethylsilane as internal standard.

[0063] Comparative Example 1

[0064] Add 0.1626 g (0.16 mmol, Mn=1000 g / mol) of double-terminated hydroxyl polytetrahydrofuran and 0.1933 g (1.67 mmol) of sarcosine NCA into a reaction bottle and dissolve them in 3 mL of DMAc. Place the reaction bottle in a 60° C. oil bath for 48 hours, precipitate in n-hexane and dry to obtain a reaction product.

[0065] The product's H NMR spectrum (CDCl3) is as follows Figure 1 shown. Figure 1The signal of sarcosine polymerization is contained in the product, indicating that sarcosine NCA is initiated. The signal of hydroxymethyl at the end of the polytetrahydrofuran raw material chain can be observed at 3.60ppm, indicating that there is still polytetrahydrofuran that has not been initiated in the product after polymerization. The GPC molecular weight of the product is 13.1kg / mol, which is far higher than the theoretical value (1.7kg / mol).

[0066] This indicates that without the addition of rare earth trifluoromethanesulfonate, terminal hydroxyl polytetrahydrofuran cannot completely initiate the polymerization of sarcosine NCA, and the polymerization controllability is very poor.

[0067] Example 1

[0068] Add 0.0524g (0.0842mmol) of lutetium trifluoromethanesulfonate, 0.9662g (8.40mmol) of sarcosine NCA and 0.3361g (0.168mmol, Mn=2000g / mol) of polytetrahydrofuran with one methyl group and one hydroxyl group at one end into a reaction bottle, and dissolve it with 17mL of DMAc. Place the reaction bottle in a 60°C oil bath for 48h, precipitate in ether, and dry the precipitate to obtain a polytetrahydrofuran-polysarcosine diblock copolymer with a number average molecular weight of 5.7kg / mol and a molecular weight distribution of 1.28.

[0069] The H NMR spectrum (DMSO-d6) of the product is as follows Figure 2 shown. Figure 2 The signals in the spectrum are clearly assigned, proving the structure of the polymerized product, and there is no signal of hydroxymethyl in the hydrogen spectrum (compared with Figure 1 The signal at 3.60 ppm indicates that the hydroxy-terminated polytetrahydrofuran completely initiated the polymerization of sarcosine NCA.

[0070] The molecular weight of the product is close to the theoretical value, indicating that the polymerization of sarcosine NCA initiated by adding rare earth trifluoromethanesulfonate to activate the terminal hydroxyl groups is well controllable.

[0071] Example 2

[0072] The preparation process is basically the same as that in Example 1, except that the initiator is replaced with a double-terminated hydroxyl polytetrahydrofuran having Mn=4000 g / mol (0.084 mmol), the molar ratio of the monomer to the hydroxyl group in the initiator is 50:1, and the molecular weight of the obtained polytetrahydrofuran-polysarcosine triblock copolymer is 11.8 kg / mol, and the molecular weight distribution is 1.32.

[0073] Example 3

[0074] The preparation process is basically the same as that of Example 1, except that:

[0075] The monomer was replaced with ε-trifluoroacetyl lysine NCA monomer;

[0076] The initiator was replaced with double-terminated hydroxyl polytetrahydrofuran with Mn=2000 g / mol (0.168 mmol), the molar ratio of the monomer to the hydroxyl group in the initiator was 100:1, and the molecular weight of the obtained polytetrahydrofuran-polyamino acid triblock copolymer was 43.8 kg / mol, and the molecular weight distribution was 1.29.

[0077] Example 4

[0078] The preparation process is basically the same as that of Example 1, except that the activator is replaced by an equimolar amount of scandium trifluoromethanesulfonate. The molecular weight of the obtained polytetrahydrofuran-polyamino acid block copolymer is 5.6 kg / mol, and the molecular weight distribution is 1.34.

[0079] Example 5

[0080] The preparation process is basically the same as that of Example 1, except that:

[0081] The activator was replaced with an equimolar amount of yttrium trifluoromethanesulfonate;

[0082] The monomer was replaced with an equimolar amount of γ-benzylglutamate, NCA;

[0083] The molecular weight of the obtained polytetrahydrofuran-polyamino acid block copolymer was 13.1 kg / mol, and the molecular weight distribution was 1.31.

[0084] Example 6

[0085] The preparation process is basically the same as that of Example 1, except that:

[0086] The activator was replaced with 0.84 mmol of lanthanum trifluoromethanesulfonate, and the molar ratio of the activator to the hydroxyl group in the initiator was 5:1;

[0087] The monomer was replaced with an equimolar amount of methionine NCA;

[0088] The molecular weight of the obtained polytetrahydrofuran-polyamino acid block copolymer was 9.2 kg / mol, and the molecular weight distribution was 1.33.

[0089] Example 7

[0090] The preparation process is basically the same as that of Example 1, except that:

[0091] The reaction solvent was replaced with an equal volume of tetrahydrofuran;

[0092] The monomer was replaced with ε-benzyloxycarbonyl lysine NCA, and the molar ratio of the monomer to the hydroxyl group in the initiator was 100:1;

[0093] The reaction temperature was replaced with 25 °C and the reaction time was replaced with 5 days;

[0094] The molecular weight of the obtained polytetrahydrofuran-polyamino acid block copolymer was 28.2 kg / mol, and the molecular weight distribution was 1.27.

[0095] Example 9

[0096] The preparation process is basically the same as that of Example 1, except that:

[0097] The reaction solvent was replaced with an equal volume of tetrahydrofuran;

[0098] The monomer was replaced with N-ethylglycine NCA, and the molar ratio of monomer to initiator was 50:1;

[0099] 2,2′-[[2-ethyl-2-[(oxiranylmethoxy)methyl]-1,3-dipropyl]bis(oxymethylene)] three-arm polytetrahydrofuran (Mn=4000 g / mol, 0.1 mmol) was used as the initiator;

[0100] The polymerization temperature was changed to 40°C;

[0101] The molecular weight of the obtained polytetrahydrofuran-polyamino acid block copolymer was 8.4 kg / mol, and the molecular weight distribution was 1.32.

[0102] The applicant declares that the present invention illustrates the detailed method of the present invention through the above embodiments, but the present invention is not limited to the above detailed method.

Claims

1. A method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation, characterized in that: The polytetrahydrofuran-polyamino acid block copolymer is prepared by using rare earth trifluoromethanesulfonate as an activator and polytetrahydrofuran containing terminal hydroxyl groups as an initiator to activate and initiate the ring-opening polymerization of α-amino acid-N-carboxylic anhydride in an organic solvent.

2. The method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation according to claim 1, characterized in that: The structural formula of the rare earth trifluoromethanesulfonate is RE(OSO2CF3)3; RE represents a rare earth element, which is selected from one or more of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.

3. The method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation according to claim 1, characterized in that: The polytetrahydrofuran containing terminal hydroxyl groups has a structural formula as shown in the following formula (I) or the following formula (II): R 1 With R 2 Independently selected from one or more of hydrogen, C1-C12 saturated aliphatic hydrocarbon group, halogen-substituted C1-C12 saturated aliphatic hydrocarbon group, C1-C12 unsaturated aliphatic hydrocarbon group, halogen-substituted C1-C12 unsaturated aliphatic hydrocarbon group, and aromatic hydrocarbon group; m is a natural number selected from 1 to 4; n1 and n2 represent the number of repeating units, and are positively correlated with the number average molecular weight of the polytetrahydrofuran containing terminal hydroxyl groups. The number average molecular weight of the polytetrahydrofuran containing terminal hydroxyl groups is 1000 to 10000 g / mol.

4. The method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation according to claim 1, characterized in that: The α-amino acid-N-carboxylic anhydride has a structural formula as shown in the following formula (III): In the formula, R 3 , R 4 Independently selected from hydrogen, C1-C9 saturated aliphatic hydrocarbon group, C1-C9 unsaturated aliphatic hydrocarbon group, aromatic hydrocarbon group, C1-C6 carboxyalkyl group with protected carboxyl group, and C1-C6 aminoalkyl group with protected amino group.

5. The method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation according to claim 4, characterized in that: The α-amino acid-N-carboxylic acid anhydride is selected from one or more of ε-benzyloxycarbonyllysine NCA, ε-trifluoroacetyllysine NCA, γ-methylglutamate NCA, γ-ethylglutamate NCA, γ-benzylglutamate NCA, β-benzylaspartate NCA, alanine NCA, phenylalanine NCA, leucine NCA, isoleucine NCA, valine NCA, glycine NCA, sarcosine NCA, and N-substituted glycine NCA.

6. The method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation according to claim 1, characterized in that: The organic solvent is selected from one or more of tetrahydrofuran, methyltetrahydrofuran, dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, dimethyl sulfoxide, sulfolane, nitrobenzene, benzonitrile, N-methylpyrrolidone, toluene, dichloromethane and chloroform.

7. The method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation according to claim 1, characterized in that: In the reaction system, the concentration of α-amino acid-N-carboxylic anhydride is 0.1-2 mmol / mL; The molar ratio of α-amino acid-N-carboxylic anhydride to the hydroxyl group in the initiator is 10 to 500:1; The molar ratio of the hydroxyl group in the activator to the initiator is 0.01 to 100:

1.

8. The method for preparing polytetrahydrofuran-polyamino acid block copolymer by rare earth trifluoromethanesulfonic acid activation according to claim 1, characterized in that: The temperature of the ring-opening polymerization is -10 to 100° C., and the time is 1 hour to 10 days.

9. A polytetrahydrofuran-polyamino acid block copolymer prepared by the method according to any one of claims 1 to 8, characterized in that: Molecular weight distribution PDI<1.40.

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