CN101805443B - Method of catalyzing and synthesizing polylactic acid with halloysite nanotubes as catalyst - Google Patents
Method of catalyzing and synthesizing polylactic acid with halloysite nanotubes as catalyst Download PDFInfo
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- CN101805443B CN101805443B CN2010101488902A CN201010148890A CN101805443B CN 101805443 B CN101805443 B CN 101805443B CN 2010101488902 A CN2010101488902 A CN 2010101488902A CN 201010148890 A CN201010148890 A CN 201010148890A CN 101805443 B CN101805443 B CN 101805443B
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- polylactic acid
- lactide
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- synthesizing polylactic
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Abstract
The invention relates to a method of catalyzing and synthesizing polylactic acid with halloysite nanotubes as catalyst. The method is characterized in that lactide serves as a monomer, the halloysite nanotubes serve as the catalyst, ring-opening polymerization reaction is carried out on the anhydrous and anaerobic condition and the polylactic acid is obtained through the post-treatment. The ring-opening polymerization reaction continues 12 to 96h at constant temperature between 25 and 280 degrees centigrade or is a microwave irradiation reaction. The microwave irradiation power is 50 to 1000w and the microwave irradiation time is 20 to 120 min. The invention uses the halloysite nanotubes with low price and easy access as the catalyst. The reaction productivity is high (more than or equal to 90 percent). The biological safety of the obtained polylactic acid is high.
Description
Technical field
The present invention relates to technical field of polymer chemistry; Be a kind of preparation method of bio-medical degradable material POLYACTIC ACID, be specifically related to use the kaolinic halloysite nanotubes of natural mineral is used for the catalysis synthesis of polylactic acid with lactide opened loop as catalyzer the method that derives from.
Background technology
POLYACTIC ACID (PLA) is one type of degradable biomedical macromolecular material.POLYACTIC ACID has excellent biodegradability, biocompatibility and biological safety; Its degraded product lactic acid can be participated in carbohydrate metabolism in the human body; Noresidue; Safety non-toxic has extensive studies and application as medicine sustained release carrier, operating suture, tissue engineering bracket material and bone renovating material etc. at biomedical sector.The general employing bulk polymerization of POLYACTIC ACID is monomer with the rac-Lactide promptly, under the effect of catalyzer, makes the rac-Lactide ring-opening polymerization generate POLYACTIC ACID with the certain reaction condition.Rac-Lactide has L, L-rac-Lactide (LLA claims levorotatory lactide again), D, D-rac-Lactide (DLA claims the dextrorotation rac-Lactide again) and D, three kinds of steric isomers of L-rac-Lactide (DLLA claims Study of Meso-Lactide again).
In the reaction of rac-Lactide ring-opening polymerization synthesizing polylactic acid, generally acknowledge that the best catalyzer of catalytic efficiency (is stannous octoate (Kricheldorf H R, et al, Polylactones 48.Sn (Oct) at present
2-initiated polymerization of lactide:A mechanisticstudy, Macromolecules, 2000,33,702.), its reaction scheme is following:
But in above-mentioned polymerization process, the metal catalyst stannous octoate can't thoroughly be removed from the synthetic polymkeric substance, causes it residual inevitably in polymkeric substance; And show according to research: stannous octoate has cytotoxicity (Saunders I K, et al, Polylactones; 39.Zn lactate-catalyzed copolymerization of L-lactide with glycolide or-caprolactone, Macromol.Chem.Phys, 1998; 199,1081; Schwarch G, et ai, Ring openingpolymerization of D; L-lactide in the presence of zinc metal and zinc lactate.Polym.Int, 1998,46; 177.); This makes with this type of material particularly as the carrier of taking medicine for a long time, the property implanted medical material etc., to have serious potential safety hazard as medical material.
Got into since 21 century, nano material is because its good characteristic is widely used in the productive life field.Carbon nanotube has wherein become the focus of nano materials research in world today's scope owing to its peculiar structure and excellent physicochemical property.But the made of carbon nanotubes cost is higher, complicated process of preparation, and can not large batch ofly produce, cause its many application only to be confined to laboratory study.And halloysite nanotubes (Halloysite Nanotubes HNTs) is a kind of natural many walls nanotube that under natural condition, is curled and formed by kaolinic lamella, and its chemical constitution is identical with kaolinite, and chemical formula is Al
4[Si
4O
10] (OH)
8.nH
2O; External diameter is about 10-50nm, and internal diameter is about 5-20nm, and length is about 2-40 μ m; Halloysite nanotubes (HNTs) lamella is made up of silicon-oxy tetrahedron and alumina octahedral; Outer wall contains certain silicon hydroxyl, and the form with secondary valence bonds such as hydrogen bond and Van der Waals forces between the structural unit combines, and structure and surface properties are special.Compare with the preparation of carbon nanotube, the raw material natural kaolin cost of preparation halloysite nanotubes (HNTs) is low, and aboundresources, kind are many, and processing technology is simple relatively.
Kaolinite is the same with other clay mineral to be layer (chain) shape silicate minerals, Heat stability is good, even calcination during to 650-700 ℃, can the kaolinic tubular structure of considerable damage yet, make its still molecular sieve characteristic of type of having concurrently zeolite channels; And kaolinite the time can lose most of middle water and planar water in heating, and to more than 530 ℃ the time, the part coordinated water is also lost; Thereby produce a large amount of new electro-adsorption centers; Microvoid structure horn of plenty more simultaneously, and its surfaces externally and internally has multiple scission of link to produce, and makes its increased activity.Therefore, the halloysite nanotubes for preparing thus has unique catalysis and characterization of adsorption.At present, halloysite nanotubes (HNTs) has broad application prospects at aspects such as pottery, medicament slow release, absorption and preparation high performance composite.
Summary of the invention
Technical problem to be solved by this invention is the deficiency to above-mentioned prior art; Providing a kind of is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes; This method is used, and halloysite nanotubes cheap, that be easy to get is made catalyzer; Reaction yield is high, and the POLYACTIC ACID biological safety for preparing is high.
For solving technical problem proposed by the invention; The technical scheme that the present invention adopts is: a kind of is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes; It is characterized in that: be monomer with the rac-Lactide, halloysite nanotubes carries out ring-opening polymerization as catalyzer under the anhydrous and oxygen-free condition; Through aftertreatment, obtain POLYACTIC ACID again.
Press such scheme, described ring-opening polymerization is 25-280 ℃ of isothermal reaction 12-96h.
Press such scheme, described ring-opening polymerization is 140-180 ℃.
Press such scheme, described isothermal reaction temperature is preferably 140 ℃, and the described isothermal reaction time is preferably 48h.
Press such scheme, described ring-opening polymerization is the microwave exposure reaction, and microwave exposure power is 50-1000W; Microwave irradiation time is 20-120min.
Press such scheme, described halloysite nanotubes is natural many walls nanotube that a kind of kaolinite lamella curls and forms under natural condition, and chemical formula is Al
4[Si
4O
10] (OH)
8.nH
2O, external diameter is about 10-60nm, and internal diameter is about 5-20nm, and length is about 2-40 μ m.
Press such scheme, described halloysite nanotubes obtains through following treatment process: get the kaolin raw material through washing, filtration, oven dry, ball milling; Solid-liquid weight ratio according to the sodium hexametaphosphate solution of kaolin raw material: 0.2-1mol/L is 1: 5, adds the sodium hexametaphosphate solution of 0.2-1mol/L, mixes, and 80-100 ℃ is stirred 4-6h, and filtration, washing and drying obtain the s.t. sample; According to s.t. sample and weight percent is that the weight ratio of the polyacrylic acid solution of 1-5% is 1: 1; Adding weight percent is the polyacrylic acid solution of 1-5%; Mix, 90-100 ℃ is stirred 10-15h, promptly gets halloysite nanotubes through filtration, washing, drying and ball milling again.
Press such scheme, described rac-Lactide is one or more the mixing in Study of Meso-Lactide, levorotatory lactide, the dextrorotation rac-Lactide, is any proportioning during multiple mixing.
Press such scheme, described aftertreatment adds acetone for after carrying out ring-opening polymerization, adds entry then, again with the deposition vacuum-drying that obtains behind the filtering water.
Press such scheme, described anhydrous and oxygen-free condition is that vacuum tightness is the vacuum condition of 1-500Pa or the inert gas atmosphere of 100-101325Pa.
The present invention is used for the rac-Lactide ring-opening polymerization with halloysite nanotubes as catalyzer and prepares POLYACTIC ACID; Can in the rac-Lactide ring-opening polymerization, bear certain template action; Make polyreaction towards certain orientation, thereby the polymkeric substance that finally obtains is had with the 3 D stereo nanostructure of halloysite nanotubes for " nuclear ".
Beneficial effect of the present invention: expensive micromolecule catalyst that (1), the present invention use cheapness, are easy to get, stable halloysite nanotubes substitutes synthetic such as sad four tin etc. are as the catalyzer of rac-Lactide ring-opening polymerization; Reaction yield high (>=90%); It is residual that the POLYACTIC ACID for preparing does not have metallic compound; Biological safety is high, and is suitable to medicine controlled release carrier and tissue engineering material.(2), when the present invention adopts microwave exposure to make rac-Lactide generation ring-opening polymerization, save time, energy-conservation.Compare with conventional heat polymerization, microwave heating can reduce energy waste significantly as a kind of intramolecularly type of heating, and also there is non-thermal effect in chemical reaction, can play the effect that promotes reaction.
Description of drawings
Fig. 1 is the sem photograph of halloysite nanotubes.
Fig. 2 is the particle diameter and the size distribution figure of halloysite nanotubes.
Fig. 3 is the hydrogen nuclear magnetic resonance spectrogram of the polylactic acid polymer that obtains of embodiment 6.
Embodiment
Through embodiment the present invention is elaborated below, but should not be regarded as limitation of the present invention.
(1) purification of halloysite nanotubes catalyzer and sign:
Get kaolin raw material 10g, through washing, filtration, oven dry, ball milling; Solid-liquid weight ratio according to the sodium hexametaphosphate solution of kaolin raw material: 0.2-1mol/L is 1: 5, adds the 0.2-1mol/L sodium hexametaphosphate solution, mixes, and 80-100 ℃ is stirred 4-6h, and filtration, washing and drying obtain the s.t. sample; According to s.t. sample and weight percent is that the weight ratio of the polyacrylic acid solution of 1-5% is 1: 1; Adding weight percent is the polyacrylic acid solution of 1-5%; Mix; 90-100 ℃ is stirred 10-15h, after disposing, promptly gets the halloysite nanotubes catalyzer through filtration, washing, drying and ball milling again.
Adopt the pattern of scanning electron microscopic observation gained halloysite nanotubes, the result sees accompanying drawing 1; Adopt the size and the distribution of sizes of the ZS90 type laser particle analyzer mensuration halloysite nanotubes particle of Britain Ma Erwen company, the result sees accompanying drawing 2.
(2) with the halloysite nanotubes be the catalyst synthesizing polylactic acid
The halloysite nanotubes that adopts above-mentioned processing to obtain among the following embodiment 1-6 is made catalyzer; Adopt commercially available halloysite nanotubes among the embodiment 7.
All adopt day island proper Tianjin LC-20AD of company type gel chromatograph among the embodiment 1-7; Be standard specimen with the monodisperse polystyrene and proofread and correct through pervasive value; THF is as solvent; Adopt μ-Styragel packed column, under 40 ℃ temperature, measure the weight-average molecular weight and the molecular weight distributing index PDI of polymkeric substance.
Embodiment 1:
The 15 gram rac-Lactides of in reaction kettle, packing into, by lactide monomer: the halloysite nanotubes catalyst weight adds 15 milligrams of halloysite nanotubes than=1000: 1; Reaction kettle is vacuumized, use the nitrogen replacement repetitive operation then three times, close reactor drum under the vacuum, reaction kettle is slowly heated, 160 ℃ of isothermal reactions 48 hours, stopped reaction is chilled to room temperature with reaction kettle then; Add the polymkeric substance that acetone obtains with solubilizing reaction, add deionized water then, polymer precipitation is separated out, the filtering water places 40 ℃ of vacuum-dryings of vacuum drying oven 48 hours with deposition at last again, obtains white powder solid POLYACTIC ACID, productive rate 92%.The weight-average molecular weight of polymer poly lactic acid is 2.0 * 10
4-6.0 * 10
4, PDI≤1.50.
Embodiment 2:
The 15 gram rac-Lactides of in reaction kettle, packing into, by lactide monomer: the halloysite nanotubes catalyst weight adds 150 milligrams of halloysite nanotubes than=100: 1; Reaction kettle is vacuumized, use the nitrogen replacement repetitive operation then three times, close reactor drum under the vacuum, reaction kettle is slowly heated, temperature of reaction is reacted 72 hours stopped reaction then for following 140 ℃, and reaction kettle is chilled to room temperature; Add the polymkeric substance that acetone obtains with solubilizing reaction, add deionized water then, polymer precipitation is separated out, the filtering water places vacuum drying oven with deposition at last again, 40 ℃ of vacuum-dryings 48 hours, obtains white powder solid POLYACTIC ACID, productive rate 95%.The weight-average molecular weight of polymer poly lactic acid is 4.0 * 10
4-9.0 * 10
4, PDI≤1.40.
Embodiment 3:
The 15 gram rac-Lactides of in reaction kettle, packing into, by lactide monomer: the halloysite nanotubes catalyst weight adds 150 milligrams of halloysite nanotubes than=100: 1; Reaction kettle is vacuumized, use the nitrogen replacement repetitive operation then three times, close reactor drum under the vacuum, reaction kettle is slowly heated, 160 ℃ are reacted 72 hours stopped reaction then under steady temperature, and reaction kettle is chilled to room temperature; Add the polymkeric substance that acetone obtains with solubilizing reaction, add deionized water then, polymer precipitation is separated out, the filtering water places vacuum drying oven with deposition at last again, 40 ℃ of vacuum-dryings 48 hours, obtains pale yellow powder shape solid, productive rate 94%.The polymkeric substance weight-average molecular weight is 1.0 * 10
4-1.5 * 10
4, PDI≤1.20.
Embodiment 4:
The 15 gram rac-Lactides of in reaction kettle, packing into, by lactide monomer: the halloysite nanotubes catalyst weight adds 30 milligrams of halloysite nanotubes than=500: 1; Reaction kettle is vacuumized, use the nitrogen replacement repetitive operation then three times, close reactor drum under the vacuum, reaction kettle is slowly heated, the following 200 ℃ of reactions of temperature of reaction 24 hours, stopped reaction is chilled to room temperature with reaction kettle then; Add the polymkeric substance that acetone obtains with solubilizing reaction, add deionized water then, polymer precipitation is separated out; The filtering water placed vacuum drying oven with deposition at last again, 40 ℃ of vacuum-dryings 48 hours; Obtain the white powder solid, productive rate 92%, the polymkeric substance weight-average molecular weight is 1.8 * 10
4-2.0 * 10
4, PDI≤1.50.
Embodiment 5:
In Glass tubing, pack into 15 the gram rac-lactides; Press lactide monomer: the halloysite nanotubes catalyst weight is than=100: 1; Add 150 milligrams of halloysite nanotubes, in vacuum tightness be under the vacuum condition of 1Pa with the microwave exposure power width of cloth of 50W according to 60min, the question response mixture is chilled to room temperature; Add the polymkeric substance that acetone obtains with solubilizing reaction; Add deionized water then, polymer precipitation is separated out, again the filtering water; At last deposition is placed 40 ℃ of vacuum-dryings of vacuum drying oven 48 hours; Obtain white powder solid POLYACTIC ACID, productive rate 90%, the weight-average molecular weight 10.5 * 10 of polymer poly lactic acid
4, PDI=1.42.
Embodiment 6:
In Glass tubing, pack into 15 the gram left racemization rac-Lactide; Press lactide monomer: the halloysite nanotubes catalyst weight is than=100: 1; Add 150 milligrams of halloysite nanotubes; In vacuum tightness be under the vacuum condition of 50Pa through the microwave exposure power width of cloth of 150W according to 30 minutes, the question response mixture is chilled to room temperature; Add the polymkeric substance that acetone obtains with solubilizing reaction; Add deionized water then, polymer precipitation is separated out, again the filtering water; At last deposition is placed 40 ℃ of vacuum-dryings of vacuum drying oven 48 hours; Obtain the white powder solid, productive rate 93%, the hydrogen nuclear magnetic resonance spectrogram of resulting polymers is seen accompanying drawing 3.Can be known by accompanying drawing 3: this polymkeric substance is a POLYACTIC ACID.The weight-average molecular weight 2.1 * 10 of polymer poly lactic acid
4, PDI=1.39.
Embodiment 7:
15 gram arbitrary proportion blended rac-lactide and the left racemization rac-Lactides of in Glass tubing, packing into; Press lactide monomer: the halloysite nanotubes catalyst weight is than=100: 1; Add 150 milligrams of halloysite nanotubes; Vacuum tightness be 50Pa vacuum condition after the microwave exposure power width of cloth of 150W according to 30 minutes, the question response mixture is chilled to room temperature; Add the polymkeric substance that acetone obtains with solubilizing reaction, add deionized water then, polymer precipitation is separated out; Filtering water again; At last deposition is placed vacuum drying oven,, obtain white powder solid POLYACTIC ACID 40 ℃ of vacuum-dryings 48 hours; Productive rate 92%, the weight-average molecular weight 2.3 * 10 of polymer poly lactic acid
4, PDI=1.36.
Among the foregoing description 1-4, rac-Lactide can be any one or the multiple mixing in Study of Meso-Lactide, levorotatory lactide, the dextrorotation rac-Lactide, is any proportioning during multiple mixing; The pressure of inert gas atmosphere is that normal pressure is 101325Pa.
Each concrete raw material that the present invention is cited, and the bound of each raw material, interval value, and the bound of processing parameter (like temperature, time etc.), interval value can both realize the present invention, do not enumerate embodiment one by one at this.
Claims (8)
1. one kind is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes; It is characterized in that: with rac-Lactide and halloysite nanotubes by weight (25-1000): 1 mixes; Under the anhydrous and oxygen-free condition, carry out ring-opening polymerization then,, obtain POLYACTIC ACID again through aftertreatment; Described halloysite nanotubes is natural many walls nanotube that a kind of kaolinite lamella curls and forms under natural condition, and chemical formula is Al
4[Si
4O
10] (OH)
8.nH
2O, external diameter are 10-60nm, and internal diameter is 5-20nm, and length is 2-40 μ m.
2. according to claim 1 is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes, it is characterized in that: described ring-opening polymerization is 25-280 ℃ of isothermal reaction 12-96h.
3. according to claim 2 is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes, it is characterized in that: described ring-opening polymerization is 140-180 ℃.
4. according to claim 2 is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes, it is characterized in that: described isothermal reaction temperature is 140 ℃, and the described isothermal reaction time is 48h.
5. according to claim 1 is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes, it is characterized in that: described ring-opening polymerization is the microwave exposure reaction, and microwave exposure power is 50-1000W, and microwave irradiation time is 20-120min.
6. according to claim 1 is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes; It is characterized in that: described rac-Lactide is one or more the mixing in Study of Meso-Lactide, levorotatory lactide or the dextrorotation rac-Lactide, is any proportioning during multiple mixing.
7. according to claim 1 is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes, it is characterized in that: described aftertreatment adds acetone for after carrying out ring-opening polymerization, adds entry then, again with the deposition vacuum-drying behind the filtering water.
8. according to claim 1 is the method for catalyst synthesizing polylactic acid with the halloysite nanotubes, it is characterized in that: described anhydrous and oxygen-free condition is that vacuum tightness is the vacuum condition of 1-500Pa or the inert gas atmosphere of 100-101325Pa.
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| CN102190781A (en) * | 2011-05-11 | 2011-09-21 | 华中师范大学 | Catalytic synthesis process of poly(epsilon-caprolactone) with calcined kaolin as catalyst |
| CN109692633A (en) * | 2017-10-23 | 2019-04-30 | 天津城建大学 | Fire-retardant carbon nanotube-galapectite aerogel composite and preparation method thereof |
| CN111116885B (en) * | 2019-12-24 | 2021-02-23 | 中国地质大学（武汉） | Method for preparing polycaprolactone by ionic liquid modified kaolin through microwave catalysis |
| CN113388099B (en) * | 2021-04-09 | 2022-06-24 | 中国地质大学（武汉） | Preparation method and application of modified HNTs (HNTs) loaded tin-based catalyst |
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