CN114479024A - Lactic acid/valeric acid copolymer, preparation method and stereocomplex thereof - Google Patents
Lactic acid/valeric acid copolymer, preparation method and stereocomplex thereof Download PDFInfo
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- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
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- C08G63/08—Lactones or lactides
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- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
- C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
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Abstract
The invention relates to the technical field of high polymer materials, in particular to a lactic acid/valeric acid copolymer, a preparation method and a stereocomplex thereof. The preparation method of the lactic acid/valeric acid copolymer comprises the following steps: and carrying out polymerization reaction by taking levorotatory lactide and levorotatory valerolactone as monomers to obtain the lactic acid/valeric acid copolymer, or carrying out polymerization reaction by taking dextrorotatory lactide and dextrorotatory valerolactone as monomers to obtain the lactic acid/valeric acid copolymer. According to the invention, the levorotatory (or dextrorotatory) valerolactone containing a flexible chain segment is introduced into the levorotatory (or dextrorotatory) lactide through a polymerization reaction, so that the toughness of the prepared lactic acid/valeric acid copolymer is improved, and the toughness of a polylactic acid stereocomplex formed by the lactic acid/valeric acid copolymer and dextrorotatory (or levorotatory) polylactic acid is further improved.
Description
Technical Field
The invention relates to the technical field of high polymer materials, in particular to a lactic acid/valeric acid copolymer, a preparation method and a stereocomplex thereof.
Background
Polylactic acid, also known as polylactide, is a polymeric material obtained by polymerizing lactic acid as a main raw material, and can be applied to the fields of injection molding, spinning, film blowing, stretch film forming, 3D printing and the like. Polylactic acid is low in price and is one of the most cost-effective biodegradable high polymer materials recognized at present.
Lactic acid, known as 2-hydroxypropionic acid or alpha-hydroxypropionic acid, is the simplest alpha-hydroxycarboxylic acid. Lactic acid has two optical isomers because it contains a chiral carbon atom in its molecule. The cyclic dimer-lactide obtained by dehydrating and polycondensing lactic acid also has chirality. Two chiral carbon atoms in the lactide molecule are both L-type or D-type, the obtained lactide is L-lactide or D-lactide, and the obtained polylactic acid also has different optical rotation.
The action force between polylactic acids having the same chemical structure but different optical rotation properties (e.g., poly-L-lactic acid and poly-D-lactic acid) is stronger than that between copolymers having the same optical rotation structure, and the co-crystallization can occur to form a stereocomplex crystal upon mixing. Compared with the levorotatory polylactic acid homopolymer and the dextrorotatory polylactic acid homopolymer, the polylactic acid stereo composite crystal has extremely high spherulite growth rate and short induction period, and the melting point of the formed copolymer is 50 ℃ higher than that of a homogeneous crystal material.
However, polylactic acid itself is hard and brittle, and its toughness is poor, and polylactic acid stereocomplex formed by stereocomplex polylactic acid is poor in toughness. In order to solve the above technical problems, patent document CN106366594A discloses a method for preparing a high-toughness polylactic acid blend containing a polylactic acid stereocomplex, wherein dextrolactic acid with high optical purity is used as a nucleating agent to react with levolactic acid in a solvent for a period of time at room temperature, so as to improve the toughness of the prepared polylactic acid blend. However, the toughness of the blends produced by this process is to be further improved.
Disclosure of Invention
In view of the above-mentioned disadvantages of the prior art, the present invention aims to provide a lactic acid/valeric acid copolymer, a preparation method and a stereocomplex thereof, so as to further improve the toughness of polylactic acid stereoblends.
In a first aspect, the present invention provides a method for preparing a lactic acid/valeric acid copolymer, comprising:
carrying out polymerization reaction by taking levorotatory lactide (also known as L-lactide) and levorotatory valerolactone (also known as L-3, 6-dipropyl-1, 4-dioxane-2, 5-diketone, L-valerolactone) as monomers to obtain the lactic acid/valeric acid copolymer;
or, taking D-lactide (also called D-lactide) and D-valerolactone (also called D-valerolactone) as monomers to carry out polymerization reaction, thus obtaining the lactic acid/valeric acid copolymer.
Optionally, the temperature of the polymerization reaction is 120-150 ℃, preferably 125-150 ℃; the polymerization time is 4 to 15 hours, preferably 5 to 15 hours.
Optionally, the mass percentage of the levolactide to the levovalerolactone is 50 wt% to 90 wt%: 50 wt% -10 wt%, preferably 50 wt% -80 wt%: 50 wt% -20 wt%, and the total amount of the two is 100%.
Optionally, the mass percentage of the D-lactide to the D-valerolactone is 50 wt% to 90 wt%: 50 wt% -10 wt%, preferably 50 wt% -80 wt%: 50 wt% -20 wt%, and the total amount of the two is 100%.
Optionally, in the polymerization process, the raw materials used further include an initiator and a catalyst.
Alternatively, the initiator may be an alcohol, and examples thereof include a monohydric alcohol, a polyhydric alcohol, etc., the monohydric alcohol may include methanol, ethanol, propanol, butanol, pentanol, hexanol, benzyl alcohol, phenethyl alcohol, phenylpropanol, phenylbutanol, phenylpentanol, phenylhexanol, etc., and the polyhydric alcohol may include ethylene glycol, glycerol, pentaerythritol, etc.
Optionally, the mass ratio of the initiator to the levorotatory lactide or the dextrorotatory lactide is 0.01-0.5: 50 to 90, preferably 0.05 to 0.5: 50-90.
Alternatively, the catalyst used is an organotin-based catalyst.
Optionally, the organotin-based catalyst includes one or more of stannous octoate, stannous chloride and butyltin. Examples of the butyltin include butylstannoic acid, tetrabutyltin, dibutyltin dilaurate and the like.
Optionally, the mass ratio of the catalyst to the levorotatory lactide or the dextrorotatory lactide is 0.01-0.5: 50 to 90, preferably 0.1 to 0.5: 50-90.
Optionally, a purification step is included after the polymerization reaction.
Optionally, the purifying comprises: the reaction product is dissolved with a solvent, followed by removing unreacted monomers with a precipitant, and then dried.
Alternatively, the solvent may be a halogenated alkane, and examples thereof include methyl chloride, methylene chloride, difluoromethane, and monoiodopropane.
Optionally, the mass ratio of the solvent to the reaction product is 5-15: 1, preferably 10 to 15: 1.
alternatively, the precipitant may be an alcohol, and examples thereof include ethanol, methanol, propanol, butanol, pentanol, and the like.
Optionally, drying to constant weight.
In a second aspect, the present invention provides a lactic acid/valeric acid copolymer prepared according to the preparation process as described above.
In another aspect, the present invention also provides a method for preparing a polylactic acid stereocomplex, comprising the steps of:
carrying out polymerization reaction by taking levorotatory lactide and levorotatory valerolactone as monomers to obtain a lactic acid/valeric acid copolymer, and then mixing the lactic acid/valeric acid copolymer with dextrorotatory polylactic acid to obtain a polylactic acid stereocomplex containing homogeneous crystals and heterogeneous crystals;
or, taking the dextro-lactide and the dextro-valerolactone as monomers to carry out polymerization reaction to obtain a lactic acid/valeric acid copolymer, and then mixing the lactic acid/valeric acid copolymer with the levorotatory polylactic acid to obtain the polylactic acid stereocomplex containing the homogeneous crystal and the heterogeneous crystal.
In the present invention, the mixing may be performed by solution mixing or melt mixing.
Optionally, the mass ratio of the lactic acid/valeric acid copolymer to the poly (D-lactic acid) or the poly (L-lactic acid) is 1-9: 9-1, preferably 2-8: 8-2.
In still another aspect, the present invention also provides a polylactic acid stereocomplex prepared according to the preparation method as described above.
As described above, the lactic acid/valeric acid copolymer, the preparation method and the polylactic acid stereocomplex thereof of the present invention have the following advantageous effects:
(1) according to the invention, the levorotatory (or dextrorotatory) valerolactone containing a flexible chain segment is introduced into the levorotatory (or dextrorotatory) lactide through a polymerization reaction, so that the toughness of the obtained lactic acid/valeric acid copolymer is improved, and the toughness of a stereocomplex formed by the lactic acid/valeric acid copolymer and the dextrorotatory (or levorotatory) polylactic acid is further improved.
(2) In the invention, the polarities of the lactide, the valerolactone and the polylactic acid are similar, the components have good compatibility, and the phase separation phenomenon does not exist in the processing process.
(3) The adopted raw materials of the poly-lactic acid with dextro-or levorotatory-elasticity have good biodegradability, and the prepared polylactic acid stereo complex has good biocompatibility.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. The parts referred to in the invention refer to parts by mass, unless otherwise specified.
The invention provides a preparation method of a lactic acid/valeric acid copolymer, which comprises the following steps:
taking levo-lactide and levo-valerolactone as monomers, and carrying out polymerization reaction for 4-15h at the temperature of 120-150 ℃ under the action of an alcohol initiator and an organic tin catalyst, wherein the mass percentage of the levo-lactide to the levo-valerolactone is 50-90 wt%: 50 wt% -10 wt%, preferably 50 wt% -80 wt%: 50-20 wt%, the total amount of the monomers is 100%; the mass ratio of the alcohol initiator to the levorotatory lactide is 0.01-0.5: 50 to 90, preferably 0.05 to 0.5: 50-90; the organic tin catalyst comprises one or more of stannous octoate, stannous chloride and butyltin, and the mass ratio of the organic tin catalyst to the levorotatory lactide is 0.01-0.5: 50 to 90, preferably 0.1 to 0.5: 50-90;
dissolving the reaction product by using halogenated alkane, wherein the mass ratio of the halogenated alkane to the reaction product is 5-15: 1, preferably 10 to 15: 1; removing unreacted monomers by using excessive alcohol, and drying to obtain a lactic acid/valeric acid copolymer;
or, taking the dextro-lactide and the dextro-valerolactone as monomers to carry out polymerization reaction, and carrying out polymerization reaction for 4-15h at the temperature of 120-150 ℃ under the action of an alcohol initiator and an organic tin catalyst, wherein the mass percentage of the dextro-lactide to the dextro-valerolactone is 50-90 wt%: 50 wt% -10 wt%, preferably 50 wt% -80 wt%: 50-20 wt%, the total amount of the monomers is 100%; the mass ratio of the alcohol initiator to the dextro-lactide is 0.01-0.5: 50 to 90, preferably 0.05 to 0.5: 50-90; the organic tin catalyst comprises one or more of stannous octoate, stannous chloride and butyltin, and the mass ratio of the organic tin catalyst to the dextro-lactide is 0.01-0.5: 50 to 90, preferably 0.1 to 0.5: 50-90;
dissolving the reaction product by using halogenated alkane, wherein the mass ratio of the halogenated alkane to the reaction product is 5-15: 1, preferably 10 to 15: 1; subsequently, unreacted monomers were removed with an excess of alcohol, followed by drying to obtain a lactic acid/valeric acid copolymer.
The invention also provides a preparation method of the polylactic acid stereocomplex, which comprises the following steps:
taking levo-lactide and levo-valerolactone as monomers, and carrying out polymerization reaction for 4-15h at the temperature of 120-150 ℃ under the action of an alcohol initiator and an organic tin catalyst, wherein the mass percentage of the levo-lactide to the levo-valerolactone is 50-90 wt%: 50 wt% -10 wt%, preferably 50 wt% -80 wt%: 50-20 wt%, the total amount of the monomers is 100%; the mass ratio of the alcohol initiator to the levorotatory lactide is 0.01-0.5: 50 to 90, preferably 0.05 to 0.5: 50-90; the organic tin catalyst comprises one or more of stannous octoate, stannous chloride and butyltin, and the mass ratio of the organic tin catalyst to the levorotatory lactide is 0.01-0.5: 50 to 90, preferably 0.1 to 0.5: 50-90;
dissolving the reaction product by using halogenated alkane, wherein the mass ratio of the halogenated alkane to the reaction product is 5-15: 1, preferably 10 to 15: 1; removing unreacted monomers by using excessive alcohol, and drying to obtain a lactic acid/valeric acid copolymer;
mixing lactic acid/valeric acid copolymer and poly (D-lactic acid) according to the mass ratio of 1-9: 9-1, and obtaining polylactic acid stereocomplex of homogeneous stereocrystals and heterogeneous stereocrystals;
or, taking the dextro-lactide and the dextro-valerolactone as monomers, and carrying out polymerization reaction for 4-15h at the temperature of 120-150 ℃ under the action of an alcohol initiator and an organic tin catalyst to obtain the lactic acid/valeric acid copolymer, wherein the mass percentage of the levo-lactide to the levo-valerolactone is 50-90 wt%: 50 wt% -10 wt%, preferably 50 wt% -80 wt%: 50-20 wt%, the total amount of the monomers is 100%; the mass ratio of the alcohol initiator to the dextro-lactide is 0.01-0.5: 50 to 90, preferably 0.05 to 0.5: 50-90; the organic tin catalyst comprises one or more of stannous octoate, stannous chloride and butyltin, and the mass ratio of the organic tin catalyst to the dextro-lactide is 0.01-0.5: 50 to 90, preferably 0.1 to 0.5: 50-90;
dissolving the reaction product by using halogenated alkane, wherein the mass ratio of the halogenated alkane to the reaction product is 5-15: 1, preferably 10 to 15: 1; removing unreacted monomers by using excessive alcohol, and drying to obtain a lactic acid/valeric acid copolymer;
mixing lactic acid/valeric acid copolymer and L-polylactic acid according to the mass ratio of 1-9: 9-1 to obtain the polylactic acid stereocomplex containing the homogeneous stereocrystals and the heterogeneous stereocrystals.
The present invention will be described in detail below with reference to specific exemplary embodiments. It should also be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention, and that numerous insubstantial modifications and adaptations of the invention described above will occur to those skilled in the art. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.
Example 1
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing a lactic acid/valeric acid copolymer: heating 50 parts of L-3, 6-dipropyl-1, 4-dioxane-2, 5-diketone (L-valerolactone) to a molten state, sequentially adding 0.1 part of n-hexanol and 0.3 part of stannous octoate into the molten L-valerolactone, and reacting at 130 ℃ for 20min, wherein the reaction system is viscous liquid; adding 50 parts of L-lactide preheated to a molten state into the viscous liquid system, stirring to uniformly mix, and continuously reacting for 8 hours at 130 ℃ to obtain a reaction product;
adding dichloromethane with the mass 10 times of that of the reaction product into the reaction product to dissolve the dichloromethane, precipitating the reaction product by using excessive ethanol to remove unreacted L-lactide and L-valerolactone monomers, and drying the reaction product in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain a lactic acid/valeric acid copolymer;
s2, synthesizing poly D-lactic acid: heating 100 parts of D-lactide to a molten state, sequentially adding 0.1 part of hexanol and 0.3 part of stannous octoate into the molten D-lactide, and reacting for 8 hours at 130 ℃;
adding dichloromethane with the mass 10 times of that of the reaction product into the reaction product to dissolve the reaction product, precipitating the reaction product by using excessive ethanol to remove unreacted lactide monomer, and drying the reaction product in a vacuum oven at the temperature of 55 ℃ and the pressure of-0.095 Pa to constant weight to obtain poly D-lactic acid;
s3, mixing: dissolving the lactic acid/valeric acid copolymer obtained in the step S1 and the poly D-lactic acid obtained in the step S2 with dichloromethane in an amount which is 10 times the mass of the lactic acid/valeric acid copolymer respectively to obtain a lactic acid/valeric acid copolymer solution and a poly D-lactic acid solution, and mixing the lactic acid/valeric acid copolymer solution and the poly D-lactic acid solution according to a mass ratio of 5: 5 under electromagnetic stirring for 4 hours, and drying in a vacuum oven at-0.095 Pa and 55 ℃ to constant weight to obtain the polylactic acid stereocomplex containing the homogeneous crystal and the heterogeneous crystal.
Example 2
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing a lactic acid/valeric acid copolymer: heating 20 parts of L-3, 6-dipropyl-1, 4-dioxane-2, 5-diketone (L-valerolactone) to a molten state, sequentially adding 0.1 part of n-hexanol and 0.3 part of stannous octoate into the molten L-valerolactone, and reacting at 130 ℃ for 20min, wherein the reaction system is viscous liquid; adding 80 parts of L-lactide preheated to a molten state into the viscous liquid system, stirring to uniformly mix, and continuously reacting for 8 hours at 130 ℃ to obtain a reaction product;
adding dichloromethane with the mass 10 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted L-lactide and L-valerolactone monomers, and drying the mixture in a vacuum oven under the conditions of-0.1 Pa and 60 ℃ to constant weight to obtain a lactic acid/valeric acid copolymer;
s2, synthesizing poly D-lactic acid: heating 100 parts of D-lactide to a molten state, sequentially adding 0.1 part of hexanol and 0.3 part of stannous octoate into the molten D-lactide, and reacting for 8 hours at 130 ℃;
adding dichloromethane with the mass of 10 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted lactide monomer, and drying the mixture in a vacuum oven under the conditions of-0.1 Pa and 60 ℃ to constant weight to obtain poly D-lactic acid;
s3, mixing: dissolving the lactic acid/valeric acid copolymer obtained in the step S1 and the poly D-lactic acid obtained in the step S2 with dichloromethane in an amount which is 10 times the mass of the lactic acid/valeric acid copolymer respectively to obtain a lactic acid/valeric acid copolymer solution and a poly D-lactic acid solution, and mixing the lactic acid/valeric acid copolymer solution and the poly D-lactic acid solution according to a mass ratio of 5: 5 mixing for 4 hours under electromagnetic stirring, and drying in a vacuum oven under the conditions of-0.1 Pa and 60 ℃ to constant weight to obtain the polylactic acid stereocomplex containing the homogeneous stereocrystal and the heterogeneous stereocrystal.
Example 3
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing a lactic acid/valeric acid copolymer: heating 50 parts of L-3, 6-dipropyl-1, 4-dioxane-2, 5-diketone (L-valerolactone) to a molten state, sequentially adding 0.3 part of n-hexanol and 0.3 part of stannous octoate into the molten L-valerolactone, and reacting at 130 ℃ for 40min, wherein the reaction system is in a viscous liquid state; adding 50 parts of L-lactide preheated to a molten state into the viscous liquid system, stirring to uniformly mix, and continuously reacting for 8 hours at 130 ℃ to obtain a reaction product;
adding dichloromethane with the mass 10 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted L-lactide and L-valerolactone monomers, and drying the mixture in a vacuum oven under the conditions of-0.1 Pa and 60 ℃ to constant weight to obtain a lactic acid/valeric acid copolymer;
s2, synthesizing poly D-lactic acid: heating 100 parts of D-lactide to a molten state, sequentially adding 0.1 part of hexanol and 0.3 part of stannous octoate into the molten D-lactide, and reacting for 8 hours at 130 ℃;
adding dichloromethane with the mass of 10 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted lactide monomer, and drying the mixture in a vacuum oven under the conditions of-0.1 Pa and 60 ℃ to constant weight to obtain poly D-lactic acid;
s3, mixing: dissolving the lactic acid/valeric acid copolymer obtained in the step S1 and the poly D-lactic acid obtained in the step S2 with dichloromethane in an amount which is 10 times the mass of the lactic acid/valeric acid copolymer respectively to obtain a lactic acid/valeric acid copolymer solution and a poly D-lactic acid solution, and mixing the lactic acid/valeric acid copolymer solution and the poly D-lactic acid solution according to a mass ratio of 5: 5 mixing for 4 hours under electromagnetic stirring, and drying in a vacuum oven under the conditions of-0.1 Pa and 60 ℃ to constant weight to obtain the polylactic acid stereocomplex containing the homogeneous stereocrystal and the heterogeneous stereocrystal.
Example 4
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing a lactic acid/valeric acid copolymer: heating 30 parts of L-3, 6-dipropyl-1, 4-dioxane-2, 5-diketone (L-valerolactone) to a molten state, sequentially adding 0.01 part of ethylene glycol and 0.01 part of stannous chloride into the molten L-valerolactone, and reacting at 150 ℃ for 40min, wherein the reaction system is in a viscous liquid state; adding 70 parts of L-lactide preheated to a molten state into the viscous liquid system, stirring to uniformly mix, and continuously reacting for 4 hours at 150 ℃ to obtain a reaction product;
adding dichloromethane with the mass 10 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted L-lactide and L-valerolactone monomers, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain a lactic acid/valeric acid copolymer;
s2, synthesizing poly D-lactic acid: heating 100 parts of D-lactide to a molten state, sequentially adding 0.01 part of hexanol and 0.01 part of stannous octoate into the molten D-lactide, and reacting for 4 hours at 150 ℃;
adding dichloromethane with the mass 10 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted lactide monomer, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain poly D-lactic acid;
s3, mixing: dissolving the lactic acid/valeric acid copolymer obtained in the step S1 and the poly D-lactic acid obtained in the step S2 with dichloromethane in an amount which is 10 times the mass of the lactic acid/valeric acid copolymer respectively to obtain a lactic acid/valeric acid copolymer solution and a poly D-lactic acid solution, and mixing the lactic acid/valeric acid copolymer solution and the poly D-lactic acid solution according to a mass ratio of 5: 5 under electromagnetic stirring for 4 hours, and drying in a vacuum oven at-0.095 Pa and 55 ℃ to constant weight to obtain the polylactic acid stereocomplex containing the homogeneous crystal and the heterogeneous crystal.
Example 5
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing a lactic acid/valeric acid copolymer: heating 50 parts of L-3, 6-dipropyl-1, 4-dioxane-2, 5-diketone (L-valerolactone) to a molten state, sequentially adding 0.5 part of benzyl alcohol and 0.5 part of dibutyltin dilaurate into the molten L-valerolactone, and reacting at 120 ℃ for 40min, wherein the reaction system is in a viscous liquid state; adding 50 parts of L-lactide preheated to be molten into the viscous liquid system, stirring to uniformly mix, and continuously reacting for 12 hours at 120 ℃ to obtain a reaction product;
adding dichloromethane with the mass 15 times of that of the reaction product into the reaction product to dissolve the dichloromethane, then using ethanol to precipitate and remove unreacted L-lactide and L-valerolactone monomers, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain a lactic acid/valeric acid copolymer;
s2, synthesizing poly D-lactic acid: heating 100 parts of D-lactide to a molten state, sequentially adding 0.5 part of hexanol and 0.5 part of stannous octoate into the molten D-lactide, and reacting for 12 hours at 120 ℃;
adding dichloromethane with the mass 15 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted lactide monomer, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain poly D-lactic acid;
s3, mixing: respectively dissolving the lactic acid/valeric acid copolymer obtained in the step S1 and the poly D-lactic acid obtained in the step S2 with dichloromethane in an amount which is 15 times the mass of the lactic acid/valeric acid copolymer to obtain a lactic acid/valeric acid copolymer solution and a poly D-lactic acid solution, and mixing the lactic acid/valeric acid copolymer solution and the poly D-lactic acid solution according to a mass ratio of 5: 5 under electromagnetic stirring for 4 hours, and drying in a vacuum oven at-0.095 Pa and 55 ℃ to constant weight to obtain the polylactic acid stereocomplex containing the homogeneous crystal and the heterogeneous crystal.
Example 6
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing a lactic acid/valeric acid copolymer: heating 30 parts of D-3, 6-dipropyl-1, 4-dioxane-2, 5-diketone (D-valerolactone) to a molten state, sequentially adding 0.01 part of ethylene glycol and 0.01 part of stannous chloride into the molten D-valerolactone, and reacting at 150 ℃ for 40min, wherein the reaction system is in a viscous liquid state; adding 70 parts of D-lactide preheated to a molten state into the viscous liquid system, stirring to uniformly mix, and continuously reacting for 4 hours at 150 ℃ to obtain a reaction product;
adding dichloromethane with the mass 5 times of that of the reaction product into the reaction product to dissolve the dichloromethane, then using ethanol to precipitate and remove unreacted D-lactide and D-valerolactone monomers, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain a lactic acid/valeric acid copolymer;
s2, synthesizing poly-L-lactic acid: heating 100 parts of L-lactide to a molten state, sequentially adding 0.01 part of hexanol and 0.01 part of stannous octoate into the molten D-lactide, and reacting for 4 hours at 150 ℃;
adding dichloromethane with the mass 5 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted lactide monomer, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain poly L-lactic acid;
s3, mixing: dissolving the lactic acid/valeric acid copolymer obtained in the step S1 and the poly D-lactic acid obtained in the step S2 with dichloromethane in an amount 5 times the mass of the lactic acid/valeric acid copolymer respectively to obtain a lactic acid/valeric acid copolymer solution and a poly L-lactic acid solution, and mixing the lactic acid/valeric acid copolymer solution and the poly L-lactic acid solution in a mass ratio of 5: 5 under electromagnetic stirring for 4 hours, and drying in a vacuum oven at-0.095 Pa and 55 ℃ to constant weight to obtain the polylactic acid stereocomplex containing the homogeneous crystal and the heterogeneous crystal.
Example 7
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing a lactic acid/valeric acid copolymer: heating 50 parts of D-3, 6-dipropyl-1, 4-dioxane-2, 5-diketone (D-valerolactone) to a molten state, sequentially adding 0.5 part of benzyl alcohol and 0.5 part of dibutyltin dilaurate into the molten D-valerolactone, and reacting at 120 ℃ for 40min, wherein the reaction system is in a viscous liquid state; adding 50 parts of D-lactide preheated to a molten state into the viscous liquid system, stirring to uniformly mix, and continuously reacting for 12 hours at 120 ℃ to obtain a reaction product;
adding dichloromethane with the mass 15 times of that of the reaction product into the reaction product to dissolve the dichloromethane, then using ethanol to precipitate and remove unreacted D-lactide and D-valerolactone monomers, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain a lactic acid/valeric acid copolymer;
s2, synthesizing poly-L-lactic acid: heating 100 parts of L-lactide to a molten state, sequentially adding 0.5 part of hexanol and 0.5 part of stannous octoate into the molten D-lactide, and reacting for 12 hours at 120 ℃;
adding dichloromethane with the mass 15 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted lactide monomer, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain poly L-lactic acid;
s3, mixing: dissolving the lactic acid/valeric acid copolymer obtained in the step S1 and the poly D-lactic acid obtained in the step S2 with 15 times of dichloromethane by mass respectively to obtain a lactic acid/valeric acid copolymer solution and a poly L-lactic acid solution, and mixing the lactic acid/valeric acid copolymer solution and the poly L-lactic acid solution according to a mass ratio of 5: 5 under electromagnetic stirring for 4 hours, and drying in a vacuum oven at-0.095 Pa and 55 ℃ to constant weight to obtain the polylactic acid stereocomplex containing the homogeneous crystal and the heterogeneous crystal.
Comparative example 1
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing poly L-lactic acid: heating 100 parts of L-lactide to a molten state, sequentially adding 0.1 part of hexanol and 0.3 part of stannous octoate into the molten D-lactide, and reacting at 130 ℃ for 8 hours to obtain poly L-lactic acid;
s2, synthesizing poly D-lactic acid: heating 100 parts of D-lactide to a molten state, sequentially adding 0.1 part of hexanol and 0.3 part of stannous octoate into the molten D-lactide, and reacting at 130 ℃ for 8 hours to obtain poly D-lactic acid;
adding dichloromethane with the mass 10 times of that of the reaction product into the reaction product to dissolve the reaction product, then using ethanol to precipitate and remove unreacted lactide monomer, and drying the mixture in a vacuum oven at the temperature of 55 ℃ under the pressure of-0.095 Pa to constant weight to obtain poly D-lactic acid;
s3, mixing: dissolving the poly L-lactic acid obtained in the step S1 and the poly D-lactic acid obtained in the step S2 with dichloromethane in an amount which is 10 times the mass of the poly L-lactic acid and the poly D-lactic acid respectively to obtain a poly L-lactic acid solution and a poly D-lactic acid solution, and mixing the poly L-lactic acid solution and the poly D-lactic acid solution in a mass ratio of 5: 5 under electromagnetic stirring for 4 hours, and drying in a vacuum oven under the conditions of-0.095 Pa and 55 ℃ to constant weight to obtain the polylactic acid stereocomplex containing the homogeneous stereocrystal.
Comparative example 2
The preparation method of the polylactic acid stereocomplex comprises the following specific steps:
s1, synthesizing D-polylactic acid: vacuum baking and degassing a 500mL reaction bottle with two air vents, repeatedly filling nitrogen for three times, adding 100g D-lactide, 3.00g diethylene glycol monomethyl ether and 0.50g stannous octoate, using toluene as a solvent, sealing the system, heating to 120 ℃, stirring and reacting for 24 hours to obtain a white crystalline polymer, adding chloroform for dissolution, using excessive ethanol for precipitation to obtain a white solid, and drying at-0.095 Pa and 55 ℃ to constant weight to obtain D-polylactic acid;
s2, mixing: respectively blending the D-polylactic acid and the L-polylactic acid obtained in the step S1 by using 15 times of dichloromethane by mass to obtain a dextrorotatory polylactic acid solution and a levorotatory polylactic acid solution, and mixing the dextrorotatory polylactic acid solution and the levorotatory polylactic acid solution according to a mass ratio of 1: 9 under electromagnetic stirring, pouring into a smooth culture dish, volatilizing at room temperature to form a film, and drying under vacuum at-0.095 Pa and 55 ℃ to constant weight to obtain the polylactic acid stereocomplex.
Performance detection
The melting temperature of the stereocomplex polylactic acid obtained in examples 1 to 7 and comparative examples 1 to 2 was measured by a Differential Scanning Calorimeter (DSC), and the results are shown in Table 1;
notched impact strength of the polylactic acid stereocomplex prepared in examples 1 to 7 and comparative examples 1 to 2 was measured according to the notched impact strength measurement method for cantilever beams in GB/T1843-2008. determination of Plastic Izod impact Strength, and the results are shown in Table 1.
TABLE 1 test results
As can be seen from Table 1, the melting temperature and notched impact strength of the polylactic acid stereocomplex prepared in examples 1-7 were significantly improved as compared with those of comparative examples 1-2, and the results show that the high temperature resistance and toughness of the polylactic acid stereocomplex were significantly improved according to the present invention.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. A method for preparing a lactic acid/valeric acid copolymer is characterized by comprising the following steps: carrying out polymerization reaction by taking levorotatory lactide and levorotatory valerolactone as monomers to obtain the lactic acid/valeric acid copolymer;
or, the lactic acid/valeric acid copolymer is obtained by polymerization reaction with dextro-lactide and dextro-valerolactone as monomers.
2. The preparation method according to claim 1, wherein the mass percentage of the levo-lactide to the levo-valerolactone is 50 wt% to 90 wt%: 50 wt% -10 wt%, and the total amount of the two is 100%;
or the mass percentage of the D-lactide to the D-valerolactone is 50 wt% -90 wt%: 50 wt% -10 wt%, and the total amount of the two is 100%.
3. The preparation method as claimed in claim 1, wherein the temperature of the polymerization reaction is 120-150 ℃, and the time of the polymerization reaction is 4-15 h;
and/or in the polymerization reaction process, the adopted raw materials also comprise an initiator and a catalyst;
and/or, after the polymerization reaction, further comprises a purification step.
4. The method according to claim 3, wherein the initiator is alcohol;
and/or the catalyst adopts an organic tin catalyst;
and/or the mass ratio of the initiator to the levorotatory lactide or the dextrorotatory lactide is 0.01-0.5: 50-90;
and/or the mass ratio of the catalyst to the levorotatory lactide or the dextrorotatory lactide is 0.01-0.5: 50-90;
and/or, the purifying comprises: the reaction product is dissolved with a solvent, followed by removing unreacted monomers with a precipitant, and then dried.
5. The method according to claim 4, wherein the organic tin catalyst comprises one or more of stannous octoate, stannous chloride and butyl tin.
6. The method according to claim 4, wherein the solvent is a halogenated alkane;
and/or the mass ratio of the solvent to the reaction product is 5-15: 1;
and/or, the precipitant is alcohol;
and/or drying to constant weight.
7. A lactic acid/valeric acid copolymer produced by the process according to any one of claims 1 to 6.
8. A preparation method of polylactic acid stereocomplex is characterized by comprising the following steps: carrying out polymerization reaction by taking levorotatory lactide and levorotatory valerolactone as monomers to obtain a lactic acid/valeric acid copolymer, and then mixing the lactic acid/valeric acid copolymer with dextrorotatory polylactic acid to obtain a polylactic acid stereocomplex containing homogeneous crystals and heterogeneous crystals;
or, taking the dextro-lactide and the dextro-valerolactone as monomers to carry out polymerization reaction to obtain a lactic acid/valeric acid copolymer, and then mixing the lactic acid/valeric acid copolymer with the levorotatory polylactic acid to obtain the polylactic acid stereocomplex containing the homogeneous crystal and the heterogeneous crystal.
9. The method according to claim 8, wherein the mass ratio of the lactic acid/valeric acid copolymer to the poly (D-lactic acid) or poly (L-lactic acid) is 1-9: 9-1.
10. The stereocomplex polylactic acid obtained by the production method according to claim 8 or 9.
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| PCT/CN2022/121605 WO2023165120A1 (en) | 2022-03-01 | 2022-09-27 | Lactic acid/pentanoic acid copolymer, preparation method and stereocomplex thereof |
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| US20090018646A1 (en) * | 2007-07-10 | 2009-01-15 | Zhao Jonathon Z | Coating Employing an Anti-Thrombotic Conjugate |
| US20100166863A1 (en) * | 2008-12-31 | 2010-07-01 | Industrial Technology Research Institute | Biodegradable copolymer hydrogels |
| JP2020189905A (en) * | 2019-05-21 | 2020-11-26 | 東レ株式会社 | Manufacturing method of polyester copolymer |
| CN113861640A (en) * | 2021-09-25 | 2021-12-31 | 浙江大学衢州研究院 | Method for improving crystallization capacity of polylactic acid copolymer material based on stereo-composition |
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| US20090018646A1 (en) * | 2007-07-10 | 2009-01-15 | Zhao Jonathon Z | Coating Employing an Anti-Thrombotic Conjugate |
| US20100166863A1 (en) * | 2008-12-31 | 2010-07-01 | Industrial Technology Research Institute | Biodegradable copolymer hydrogels |
| JP2020189905A (en) * | 2019-05-21 | 2020-11-26 | 東レ株式会社 | Manufacturing method of polyester copolymer |
| CN113861640A (en) * | 2021-09-25 | 2021-12-31 | 浙江大学衢州研究院 | Method for improving crystallization capacity of polylactic acid copolymer material based on stereo-composition |
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