WO2019011009A1 - 一种聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法 - Google Patents

一种聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法 Download PDF

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WO2019011009A1
WO2019011009A1 PCT/CN2018/080765 CN2018080765W WO2019011009A1 WO 2019011009 A1 WO2019011009 A1 WO 2019011009A1 CN 2018080765 W CN2018080765 W CN 2018080765W WO 2019011009 A1 WO2019011009 A1 WO 2019011009A1
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polypropylene carbonate
cellulose nanocrystal
oxygen
cellulose
propylene oxide
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French (fr)
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解孝林
李晓静
王勇
周兴平
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Huazhong University of Science and Technology
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Huazhong University of Science and Technology
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G64/00—Macromolecular compounds obtained by reactions forming a carbonic ester link in the main chain of the macromolecule
    • C08G64/20—General preparatory processes
    • C08G64/32—General preparatory processes using carbon dioxide
    • C08G64/34—General preparatory processes using carbon dioxide and cyclic ethers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L69/00—Compositions of polycarbonates; Compositions of derivatives of polycarbonates
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2201/00—Properties
    • C08L2201/06—Biodegradable
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2201/00—Properties
    • C08L2201/08—Stabilised against heat, light or radiation or oxydation

Definitions

  • the invention belongs to the field of degradable polymer materials, and more particularly to a preparation method for preparing a polypropylene carbonate/cellulose nanocrystal composite by in-situ polymerization.
  • PPC Polypropylene carbonate
  • PPC is a copolymerization product of carbon dioxide and propylene oxide
  • PPC has become a potential ideal replacement for food packaging, medical materials, mulch films, adhesives, and engineering plastics due to its full biodegradability, biocompatibility, and excellent oxygen barrier properties.
  • PPC has asymmetrical main chain structure and is completely amorphous plastic.
  • the glass transition temperature is only about 35 °C, and its thermal stability and mechanical properties are not ideal, which limits its large scale.
  • Marketization The modification of polypropylene carbonate has become an inevitable choice. Common methods include blend modification of other polymers, filler filling modification, and the like.
  • Cellulose nanocrystals can be used as a filler to fill modified polypropylene carbonate.
  • Cellulose nanocrystals are biodegradable materials with high crystallinity and high strength with a diameter of 5-20 nm and an aspect ratio of 1 to 100. Its excellent mechanical properties, good biocompatibility and regenerability make it an ideal reinforcing filler for degradable polymers.
  • cellulose nanocrystalline filled modified polypropylene carbonate composites are typically prepared by melt blending or solution blending (Composites Science and Technology 2013, 78: 63-68). Due to the large free energy of the surface of the cellulose nanocrystals, it is easy to entangle and agglomerate.
  • the cellulose nanocrystals are difficult to be uniformly dispersed in the polypropylene carbonate matrix.
  • the polypropylene carbonate/cellulose nanocrystalline composite prepared by the blending method has poor interfacial compatibility, and the excellent properties of the cellulose nanocrystals are difficult to be fully exerted.
  • an object of the present invention is to provide a method for preparing a polypropylene carbonate/cellulose nanocrystal composite material, wherein the overall process design and the various steps are critical to the preparation method.
  • the parameter conditions (such as the gas environment in which the reaction is carried out, the type and ratio of the reaction raw materials, the reaction temperature and time, etc.) are improved, and the filler cellulose nanocrystals can be effectively solved in the polypropylene carbonate matrix compared with the prior art.
  • the polymerization of the polypropylene carbonate/cellulose nanocrystal composite material is simple in operation and suitable for large-scale production.
  • a method for preparing a polypropylene carbonate/cellulose nanocrystal composite material which comprises the following steps:
  • the cellulose nanocrystals are carboxylated cellulose nanocrystals; and the cellulose nanocrystals are 0.5 to 10% by weight of the propylene oxide.
  • the catalyst is selected from the group consisting of a metal Schiff base complex catalyst and a metal porphyrin complex catalyst;
  • metal Schiff base complex catalyst has a structure as shown in formula (I):
  • R 1 is H, halogen, C 1 - C 20 alkyl group, C 1 - C 20 alkoxy group, fluorine-substituted C 1 - C 20 alkyl group, and fluorine-substituted aromatic group.
  • X is selected from the group consisting of Cl, N 3 , ClO 4 , BF 4 , NO 3 , CH 3 COO, CCl 3 COO, p-toluenesulfonate, o-nitrophenol oxygen, p-nitrophenol oxygen , m-nitrophenol oxygen, 2,4-dinitrophenol oxygen, 3,5-dinitrophenol oxygen, 2,4,6-trinitrophenol oxygen, 3,5-dichlorophenol oxygen, 3, Any one of 5-difluorophenol oxygen, 3,5-di-trifluoromethylphenol oxygen, and pentafluorophenol oxygen anion; M is selected from any one of Mg, Co, Zn, Cr, and Al. ;
  • the metalloporphyrin complex catalyst has a structure as shown in formula (II):
  • R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from the group consisting of H, halogen, C 1 -C 20 alkyl group, C 1 -C 20 alkoxy group, and fluorine.
  • X is selected from the group consisting of Cl, N 3 , ClO 4 , BF 4 , NO 3 , CH 3 COO, CCl 3 COO, and Benzosulfonate, o-nitrophenol oxygen, p-nitrophenol oxygen, m-nitrophenol oxygen, 2,4-dinitrophenol oxygen, 3,5-dinitrophenol oxygen, 2,4,6-three Any one of nitrophenol oxygen, 3,5-dichlorophenol oxygen, 3,5-difluorophenol oxygen, 3,5-di-trifluoromethylphenol oxygen, and pentafluorophenol oxygen anion; M selection Any one of Mg, Co, Zn, Cr, and Al;
  • the molar ratio of the catalyst to the propylene oxide is from 1:1000 to 1:8,000.
  • the cocatalyst is a substance having a quaternary phosphonium salt structure, and preferably, the cocatalyst has a structure represented by the formula (III):
  • Y is Cl, N 3 , ClO 4 , BF 4 , NO 3 , CH 3 COO, CCl 3 COO, o-nitrophenol oxygen, p-nitrophenol oxygen, m-nitrophenol oxygen, 2 , 4-dinitrophenoloxy, 3,5-dinitrophenoloxy, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, 3,5-difluorophenoloxy, 3 Any one of 5-di-trifluoromethylphenol oxygen and pentafluorophenol oxygen anion;
  • the molar ratio of the catalyst to the cocatalyst is from 1:1 to 1:10.
  • the solvent is any one of N,N-dimethylformamide, dichloromethane, acetone, toluene, and tetrahydrofuran; the propylene oxide
  • the molar ratio to the solvent is from 1:1 to 1:5.
  • the stirring speed used in the stirring is 100 to 600 rpm/min.
  • the in-situ polymerization reaction is carried out under a carbon dioxide atmosphere having an initial carbon dioxide pressure of 1 to 3 MPa.
  • the solvent is one of N,N-dimethylformamide, dichloromethane, acetone, toluene, and tetrahydrofuran.
  • the number average molecular weight of the polypropylene carbonate is from 13.6 to 93.2 kg/mol
  • the polydispersity index of the polypropylene carbonate is from 1.08 to 1.2.
  • the cellulose nanocrystals are uniformly dispersed in the polypropylene carbonate matrix by using the in-situ polymerization to prepare the polypropylene carbonate/cellulose nanocrystal composite material compared with the prior art.
  • the dispersibility is good, and the agglomeration of the cellulose nanocrystals is effectively avoided, thereby improving the dimensional stability of the filler cellulose nanocrystals in the composite material; in the present invention, the cellulose nanocrystals and the propylene oxide are first uniformly mixed to obtain a dispersion liquid.
  • the present invention is carried out under a high pressure carbon dioxide atmosphere, and the initial gas pressure value of carbon dioxide is preferably 1 to 3 MPa.
  • the gas pressure value of carbon dioxide By controlling the gas pressure value of carbon dioxide, the influence of the carbon dioxide gas pressure being too low or too high on the activity of the catalyst can be avoided (for example, the catalyst is lost). live).
  • in-situ polymerization is carried out in the presence of a catalyst and a co-catalyst, and the catalyst can copolymerize propylene oxide and carbon dioxide; and the co-catalyst plays a key role in the catalytic activity of the catalyst.
  • the invention particularly utilizes a metal Schiff base complex catalyst or a metal porphyrin complex catalyst having a specific chemical formula (i.e., a metal Schiff base complex catalyst having the structure of Formula I, having a structure as shown in Formula II) a porphyrin complex catalyst) as a catalyst, and at the same time, a cocatalyst having a quaternary phosphonium salt structure (especially a substance having a quaternary phosphonium salt structure as shown in Formula III), between them, and other reaction materials thereof
  • the overall coordination between propylene oxide, cellulose nanocrystals, etc. causes the carboxyl group on the cellulose surface to initiate the copolymerization of carbon dioxide and propylene oxide to form polypropylene carbonate in situ to obtain polypropylene carbonate/cellulose.
  • the present invention also controls the ratio of each raw material in the in-situ polymerization reaction system, preferably, the cellulose nanocrystal is 0.5 to 10% by weight of propylene oxide, and the molar ratio of propylene oxide to solvent is 1:1 to 1: 5 (solvent can make cellulose nanocrystals more uniformly dispersed), the molar ratio of catalyst to propylene oxide is 1:1000 ⁇ 1:8000, and the molar ratio of catalyst to cocatalyst is 1:1 ⁇ 1:10.
  • the integral coordination between the reaction materials enables the in-situ polymerization reaction to be carried out efficiently, and the obtained cellulose nanocrystals in the obtained polypropylene carbonate/cellulose nanocrystal composite material can be uniformly dispersed in the matrix polypropylene carbonate, and is effectively controlled.
  • the number average molecular weight and polydispersity index of the polypropylene carbonate is effectively controlled.
  • the method has mild reaction conditions and good repeatability, and utilizes the good dispersion property of cellulose nanocrystals in an organic solvent to improve the dispersion uniformity of the cellulose nanocrystals as a filler in the polypropylene carbonate matrix, and can also improve the fiber.
  • the compatibility of the nanocrystals and the polypropylene carbonate significantly improves the mechanical properties and thermal stability of the polypropylene carbonate composite.
  • the technical scheme of the invention has simple operation, mild reaction conditions, good repeatability in the preparation process and low preparation cost. Moreover, the polypropylene carbonate/cellulose nanocrystalline composite material prepared by the invention has the following advantages:
  • Polypropylene carbonate/cellulose nanocrystalline composite material is a fully biodegradable polymer material with excellent biocompatibility
  • Polypropylene carbonate-coated cellulose nanocrystals can be well dispersed in an organic solvent and can not settle for a long time;
  • Cellulose nanocrystals can improve the mechanical properties and thermal stability of polypropylene carbonate matrix materials.
  • the present invention utilizes carboxylated cellulose nanocrystals (such as carboxylated oxidized by TEMPO).
  • carboxylated cellulose nanocrystals such as carboxylated oxidized by TEMPO.
  • the in-situ polymerization of carbon dioxide and epoxide is initiated by the carboxyl group on the surface of the cellulose nanocrystal by selecting a catalyst having a specific chemical structural formula (including, of course, a co-catalyst used in combination with the catalyst).
  • the product can be further optimized by controlling other reaction conditions and parameters such as the ratio of the catalyst to the monomer.
  • the invention controls the polymerization to obtain a polypropylene carbonate-coated cellulose nanocrystal, especially by controlling the kind of the catalyst and the cocatalyst, the ratio of the catalyst to the monomer, the reaction temperature and the reaction time, so that the prepared polypropylene carbonate/ In the cellulose nanocrystal composite material, the number average molecular weight of the polypropylene carbonate is from 13.6 to 93.2 kg/mol, and the polydispersity index of the polypropylene carbonate is from 1.08 to 1.2.
  • Example 1 is a transmission electron micrograph of a polypropylene carbonate-coated cellulose nanocrystal prepared in Example 1 (the scale bar represents 0.5 ⁇ m in the drawing).
  • thermogravimetric analysis curve of the polypropylene carbonate-coated cellulose nanocrystals prepared in Example 3. It can be seen from the figure that the thermal decomposition temperature of the polypropylene carbonate-coated cellulose nanocrystals is significantly higher than that of the cellulose nanocrystals and the polypropylene carbonate.
  • Example 4 is a scanning electron micrograph of a polypropylene carbonate/cellulose nanocrystal prepared in Example 4.
  • the white dots in the figure represent cellulose nanocrystals coated with polypropylene carbonate; it can be seen from the figure that the polypropylene carbonate-coated cellulose nanocrystals can be uniformly dispersed in the polypropylene carbonate matrix.
  • the preparation method of the polypropylene carbonate/cellulose nanocrystal composite material of the present invention is a method for preparing a polypropylene carbonate by using an in-situ copolymerization method; and a preparation method of the polypropylene carbonate/cellulose nanocrystal composite material, which may specifically include the following step:
  • step (3) introducing carbon dioxide into the propylene oxide and cellulose nanocrystal dispersion obtained in the step (2), and in situ polymerization at 20 to 120 ° C for 5 to 25 hours under a sealed high pressure condition, and then cooling to At room temperature, the carbon dioxide in the autoclave is released to obtain a polypropylene carbonate-coated cellulose nanocrystal mixture;
  • the polypropylene carbonate-coated cellulose nanocrystal solution of the step (4) is precipitated with methanol and dried to further remove the catalyst and the unreacted monomer, thereby preparing a polypropylene carbonate/cellulose nanocrystal composite. material.
  • the catalyst used in the step (1) may be selected from a metal Schiff base complex catalyst or a metal porphyrin complex catalyst, and the metal Schiff base complex catalyst has a structure represented by the formula (I); a metal porphyrin complex catalyst Has the structure shown in formula (II):
  • R 1 , R 2 , R 3 , R 4 , R 5 , R 6 are each independently selected from the group consisting of: H, halogen, C 1 -C 20 alkyl, C 1 -C 20 alkoxy, fluoro substituted alkane One of the fluoro-substituted aryl groups.
  • R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from the group consisting of hydrogen and halogen; preferably, X is selected from the group consisting of Cl, N 3 , ClO 4 , BF 4 , NO 3 , CH 3 COO, CCl 3 COO, p-toluenesulfonate, o-nitrophenol oxygen, p-nitrophenol oxygen, m-nitrophenol oxygen, 2,4-dinitrophenol oxygen, 3,5-dinitrophenol Oxygen, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, 3,5-difluorophenoloxy, 3,5-di-trifluoromethylphenoloxy or pentafluorophenol oxygen anion One of them.
  • X is selected from the group consisting of Cl, N 3 , ClO 4 , BF 4 , and NO 3 ;
  • M is one selected from the group consisting of Mg, Co, Zn, Cr, and Al, and more preferably M is selected from the group consisting of Co and Al. .
  • the cocatalyst used in the step (1) is a substance having a quaternary phosphonium salt structure selected from one of the formula (III).
  • Y is Cl, N 3 , ClO 4 , BF 4 , NO 3 , CH 3 COO, CCl 3 COO, o-nitrophenol oxygen, p-nitrophenol oxygen, m-nitrophenol oxygen, 2, 4-dinitrophenoloxy, 3,5-dinitrophenoloxy, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, 3,5-difluorophenoloxy, 3, One of 5-di-trifluoromethylphenol oxygen or pentafluorophenol oxygen anion; more preferably, Y in formula (III) is Cl, N 3 , ClO 4 , BF 4 , NO 3 , CH 3 COO, CCl 3 COO.
  • the autoclave was uniformly mixed under an ice bath condition at 400 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 2 MPa of carbon dioxide is passed into the propylene oxide and cellulose nanocrystal dispersion (the pressure of carbon dioxide refers to the initial equilibrium pressure after the carbon dioxide in the dispersion has dissolved; that is, the specific pressure of carbon dioxide is introduced into the high pressure reactor.
  • the pressure in the dispersion reaches saturation, the carbon dioxide pressure in the autoclave will remain stable, maintaining a stable carbon dioxide pressure corresponding to the initial equilibrium pressure), and releasing the high pressure reaction after 12 hours of in situ polymerization at 20 °C.
  • Carbon dioxide in the kettle obtaining a mixture of cellulose nanocrystals coated with polypropylene carbonate, diluting the polypropylene carbonate coated cellulose nanocrystal mixture with dichloromethane, and then coating the polypropylene carbonate coated cellulose
  • the nanocrystalline solution was precipitated with methanol and dried to obtain a polypropylene carbonate/cellulose nanocrystal composite.
  • the cellulose nanocrystal content is 0.5% by weight
  • the number average molecular weight of the polypropylene carbonate is 13.6 kg/mol
  • the polydispersity index of the polypropylene carbonate is 1.08.
  • FIG. 1 A transmission electron micrograph of the polypropylene carbonate-modified cellulose nanocrystals prepared in Example 1 is shown in Fig. 1.
  • the autoclave was uniformly mixed under ice bath conditions at 100 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 3 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and polymerized in situ at 120 ° C for 20 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with N,N-dimethylformamide, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol, Drying to produce a polypropylene carbonate/cellulose nanocrystalline composite.
  • the cellulose nanocrystal content is 1% by weight, the number average molecular weight of the polypropylene carbonate is 19.1 kg/mol, and the polydispersity index of the polypropylene carbonate is 1.10.
  • the cellulose nanocrystal content was 1.5% by weight, the number average molecular weight of the polypropylene carbonate was 34.1 kg/mol, and the polydispersity index of the polypropylene carbonate was 1.09.
  • the thermogravimetric analysis curve of the polypropylene carbonate coated cellulose nanocrystal prepared in Example 3 is shown in Fig. 3.
  • the cellulose nanocrystal content is 2% by weight, the number average molecular weight of the polypropylene carbonate is 32.1 kg/mol, and the polydispersity index of the polypropylene carbonate is 1.12.
  • the scanning electron micrograph of the polypropylene carbonate/cellulose nanocrystal composite prepared in Example 4 is shown in FIG. 4 .
  • 3 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and polymerized in situ at 40 ° C for 25 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with N,N-dimethylformamide, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol, Drying to produce a polypropylene carbonate/cellulose nanocrystalline composite.
  • the cellulose nanocrystal content is 4% by weight, the number average molecular weight of the polypropylene carbonate is 31.5 kg/mol, and the polydispersity index of the polypropylene carbonate is 1.14.
  • the autoclave was uniformly mixed under ice bath conditions at 500 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 2 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and the polymerization was carried out in situ at 120 ° C for 25 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with N,N-dimethylformamide, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol, Drying to produce a polypropylene carbonate/cellulose nanocrystalline composite.
  • the cellulose nanocrystal content is 5 wt%
  • the number average molecular weight of the polypropylene carbonate is 93.2 kg/mol
  • the polydispersity index of the polypropylene carbonate is 1.2
  • the autoclave was uniformly mixed under an ice bath condition at 400 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 3 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and polymerized in situ at 110 ° C for 20 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with N,N-dimethylformamide, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol, Drying to produce a polypropylene carbonate/cellulose nanocrystalline composite.
  • the cellulose nanocrystal content is 5% by weight, the number average molecular weight of the polypropylene carbonate is 92.7 kg/mol, and the polydispersity index of the polypropylene carbonate is 1.18.
  • the autoclave was uniformly mixed under ice bath conditions at 500 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 2 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and polymerized in situ at 100 ° C for 16 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with toluene, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol and dried to obtain a polypropylene carbonate.
  • /Cellulose nanocrystalline composite The cellulose nanocrystal content is 5 wt%, the number average molecular weight of the polypropylene carbonate is 91.8 kg/mol, and the polydispersity index of the polypropylene carbonate is 1.16.
  • the autoclave was uniformly mixed under an ice bath condition at 600 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 3 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and polymerized in situ at 100 ° C for 18 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with toluene, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol and dried to obtain a polypropylene carbonate.
  • /Cellulose nanocrystalline composite The cellulose nanocrystal content is 5 wt%, the number average molecular weight of the polypropylene carbonate is 91.0 kg/mol, and the polydispersity index of the polypropylene carbonate is 1.12.
  • the autoclave was uniformly mixed under an ice bath condition at 600 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 2 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and polymerized in situ at 90 ° C for 20 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate-coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with toluene, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol and dried to obtain a polypropylene carbonate.
  • the cellulose nanocrystal content is 5 wt%
  • the number average molecular weight of the polypropylene carbonate is 90.8 kg/mol
  • the polydispersity index of the polypropylene carbonate is 1.15.
  • the autoclave was uniformly mixed under an ice bath condition at 600 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 2 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and polymerized in situ at 85 ° C for 21 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with N,N-dimethylformamide, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol, Drying to produce a polypropylene carbonate/cellulose nanocrystalline composite.
  • the cellulose nanocrystal content is 5 wt%
  • the number average molecular weight of the polypropylene carbonate is 92.4 kg/mol
  • the polydispersity index of the polypropylene carbonate is 1.20.
  • the autoclave was uniformly mixed under an ice bath condition at 600 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 3 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and polymerized in situ at 80 ° C for 20 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with toluene, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol and dried to obtain a polypropylene carbonate.
  • /Cellulose nanocrystalline composite The cellulose nanocrystal content is 5 wt%, the number average molecular weight of the polypropylene carbonate is 91.4 kg/mol, and the polydispersity index of the polypropylene carbonate is 1.16.
  • the autoclave was uniformly mixed under ice bath conditions at 500 rpm/min to obtain a propylene oxide and cellulose nanocrystal dispersion.
  • 3 MPa of carbon dioxide was passed into the propylene oxide and cellulose nanocrystal dispersion, and the polymerization was carried out in situ at 90 ° C for 22 hours, then cooled to room temperature, and the carbon dioxide in the autoclave was released to obtain a polypropylene carbonate-coated a cellulose nanocrystal mixture, the polypropylene carbonate coated cellulose nanocrystal mixture is diluted with toluene, and then the polypropylene carbonate coated cellulose nanocrystal solution is precipitated with methanol and dried to obtain a polypropylene carbonate.
  • the cellulose nanocrystal content is 4% by weight
  • the number average molecular weight of the polypropylene carbonate is 30.8 kg/mol
  • the polydispersity index of the polypropylene carbonate is 1.12.
  • the polypropylene carbonate/cellulose nanocrystalline composite material prepared in the above examples has greatly improved mechanical properties and thermal stability. It can be seen from the transmission electron micrograph of Fig. 1 that the cellulose nanocrystals are coated with polypropylene carbonate and uniformly dispersed; the heat loss analysis curve 3 shows that the heat of the polypropylene carbonate coated cellulose nanocrystals The decomposition temperature is significantly higher than that of ordinary cellulose nanocrystals and polypropylene carbonates, indicating that the cellulose carbonate-coated cellulose has strong interfacial interaction between cellulose nanocrystals and polypropylene carbonate, and can be very good. Dispersion, its mechanical and thermal properties must be greatly improved. It can be seen from the scanning electron micrograph of Fig.
  • the cellulose nanocrystals coated with the polypropylene carbonate can be uniformly dispersed in the polypropylene carbonate. It can be seen that the dispersion of cellulose nanocrystals in the matrix is good, and the agglomeration between the particles is effectively avoided, so that the dimensional stability of the filler cellulose nanocrystals in the composite material is correspondingly improved.
  • the various reagents used in the present invention are commercially available or can be prepared by themselves using the preparation methods described in the prior art.
  • the carboxylated cellulose nanocrystals used in the present invention can be subjected to carboxylation treatment of commercially available cellulose nanocrystals by a conventional method in the prior art, and the carboxylation treatment can be carried out by a conventional treatment process, cellulose nanocrystals.
  • the carboxyl grafting of the surface has no effect on the addition ratio of the cellulose nanocrystals and the subsequent polymerization reaction, as long as the carboxyl group is present; for example, the treatment process of the TEMPO oxidized cellulose nanocrystal can be referred to the reference Biomacromolecules 2004, 5, 1983. -1989.

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Abstract

本发明公开了一种聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，包括以下步骤：(1)在保护性气体的保护下，将纤维素纳米晶、环氧丙烷、催化剂、助催化剂、以及溶剂混合均匀得到环氧丙烷/纤维素纳米晶分散液；(2)向该分散液中通入二氧化碳，然后在密封环境下于20～120℃下进行原位聚合反应5～25小时，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物；(3)用溶剂稀释并用甲醇沉淀，然后干燥，即得到聚丙撑碳酸酯/纤维素纳米晶复合材料。本发明通过对该制备方法关键的整体流程工艺设计、以及各个步骤的参数条件进行改进，能够有效解决填料纤维素纳米晶在聚丙撑碳酸酯基体中易团聚、分散不均匀的问题。

Description

一种聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法 【技术领域】
本发明属于可降解聚合物材料领域，更具体地，涉及一种通过原位聚合制备聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法。
【背景技术】
传统的高分子材料在给人类社会带来巨大物质财富的同时，也带来了“白色污染”。开发生物可降解高分子材料是实现环境和资源可持续发展的必然趋势。聚丙撑碳酸酯(PPC)是二氧化碳与环氧丙烷的共聚产物，是一种可生物降解高分子材料。因其完全生物可降解性、生物相容性、优良的阻氧隔湿性等优点，PPC已成为食品包装、医用材料、地膜、胶黏剂以及工程塑料的潜在的理想替代品。然而，作为脂肪族的聚碳酸酯，PPC的主链结构不对称，属于完全非结晶塑料，玻璃化温度仅35℃左右，其热稳定性、力学性能等综合性能不够理想，限制了其大规模市场化。聚丙撑碳酸酯的改性成为必然选择，常用的方法包括采用其它聚合物的共混改性，填料填充改性等。
纤维素纳米晶作为一种填料可用于填充改性聚丙撑碳酸酯，纤维素纳米晶是一种直径为5～20nm、长径比为1～100的结晶度高、强度大的生物可降解材料，其优良的力学性能、良好的生物相容性及可再生的特点使其成为可降解聚合物理想的增强填料。目前，纤维素纳米晶填充改性的聚丙撑碳酸酯复合材料通常采用熔融共混或溶液共混法制备(Composites Science and Technology 2013,78：63-68)。由于纤维素纳米晶表面自由能大，极易缠结和发生团聚，共混过程中，纤维素纳米晶很难在聚丙撑碳酸酯基体中均匀分散。共混法制得的聚丙撑碳酸酯/纤维素纳米晶复合材料界面相容性差，纤维素纳米晶的优良特性难以得到充分发挥。
【发明内容】
针对现有技术的以上缺陷或改进需求，本发明的目的在于提供一种聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其中通过对该制备方法关键的整体流程工艺设计、以及各个步骤的参数条件(如反应所处气体环境、反应原料的种类及配比、反应温度及时间等)进行改进，与现有技术相比能够有效解决填料纤维素纳米晶在聚丙撑碳酸酯基体中易团聚、分散不均匀的问题，改善聚丙撑碳酸酯的力学和热学性能，并提高了聚丙撑碳酸酯/纤维素纳米晶复合材料中填料纤维素纳米晶的尺寸稳定性，并且该方法是利用原位聚合制备聚丙撑碳酸酯/纤维素纳米晶复合材料，操作简单，适合规模化生产。
为实现上述目的，按照本发明，提供了一种聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，包括以下步骤：
(1)在保护性气体的保护下，将纤维素纳米晶、环氧丙烷、催化剂、助催化剂、以及溶剂混合得到环氧丙烷/纤维素纳米晶混合液；接着，将所述环氧丙烷/纤维素纳米晶混合液在冰浴条件下进行搅拌，得到混合均匀的环氧丙烷/纤维素纳米晶分散液；
(2)向所述步骤(1)得到的所述环氧丙烷/纤维素纳米晶分散液中通入二氧化碳，然后在密封环境下于20～120℃下进行原位聚合反应5～25小时，使得所述环氧丙烷/纤维素纳米晶分散液在二氧化碳气氛下进行原位聚合反应得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物；
(3)用溶剂稀释所述步骤(2)得到的所述聚丙撑碳酸酯包覆的纤维素纳米晶混合物，得到聚丙撑碳酸酯包覆的纤维素纳米晶溶液；接着，对该聚丙撑碳酸酯包覆的纤维素纳米晶溶液用甲醇沉淀，然后干燥，即得到聚丙撑碳酸酯/纤维素纳米晶复合材料。
作为本发明的进一步优选，所述步骤(1)中，所述纤维素纳米晶为羧基化纤维素纳米晶；所述纤维素纳米晶为所述环氧丙烷的0.5～10wt％。
作为本发明的进一步优选，所述步骤(1)中，所述催化剂选自金属席夫碱配合物催化剂、以及金属卟啉配合物催化剂中的任意一种；
其中，所述金属席夫碱配合物催化剂具有如式(I)所示结构：
Figure PCTCN2018080765-appb-000001
该式(I)中，R 1为H、卤素、C 1-C 20的烷基、C 1-C 20的烷氧基、氟取代的C 1-C 20的烷基、以及氟取代的芳基中的任意一种；X选自Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO、对甲基苯磺酸根、邻硝基苯酚氧、对硝基苯酚氧、间硝基苯酚氧、2，4-二硝基苯酚氧、3，5-二硝基苯酚氧、2，4，6-三硝基苯酚氧、3，5-二氯苯酚氧、3，5-二氟苯酚氧、3，5-二-三氟甲基苯酚氧、以及五氟酚氧负离子中的任意一种；M选自Mg、Co、Zn、Cr、以及Al中的任意一种；
所述金属卟啉配合物催化剂具有如式(II)所示结构：
Figure PCTCN2018080765-appb-000002
该式(II)中，R 2、R 3、R 4、R 5、R 6各自独立的选自H、卤素、C 1-C 20 的烷基、C 1-C 20的烷氧基、氟取代的C 1-C 20的烷基、以及氟取代的芳基中的任意一种；X选自Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO、对甲基苯磺酸根、邻硝基苯酚氧、对硝基苯酚氧、间硝基苯酚氧、2，4-二硝基苯酚氧、3，5-二硝基苯酚氧、2，4，6-三硝基苯酚氧、3，5-二氯苯酚氧、3，5-二氟苯酚氧、3，5-二-三氟甲基苯酚氧、以及五氟酚氧负离子中的任意一种；M选自Mg、Co、Zn、Cr、以及Al中的任意一种；
此外，所述催化剂与所述环氧丙烷的摩尔比为1:1000～1:8000。
作为本发明的进一步优选，所述步骤(1)中，所述助催化剂为具有季鏻盐结构的物质，优选的，所述助催化剂具有如式(III)所示结构：
Figure PCTCN2018080765-appb-000003
该式(III)中，Y为Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO、邻硝基苯酚氧、对硝基苯酚氧、间硝基苯酚氧、2，4-二硝基苯酚氧、3，5-二硝基苯酚氧、2，4，6-三硝基苯酚氧、3，5-二氯苯酚氧、3，5-二氟苯酚氧、3，5-二-三氟甲基苯酚氧、以及五氟酚氧负离子中的任意一种；
所述催化剂与所述助催化剂的摩尔比为1:1～1:10。
作为本发明的进一步优选，所述步骤(1)中，所述溶剂为N，N-二甲基甲酰胺、二氯甲烷、丙酮、甲苯、以及四氢呋喃中的任意一种；所述环氧丙烷与所述溶剂的摩尔比为1:1～1:5。
作为本发明的进一步优选，所述步骤(1)中，所述搅拌所采用的搅拌速度为100～600rpm/min。
作为本发明的进一步优选，所述步骤(2)中，所述原位聚合反应是在初始二氧化碳的压力为1～3MPa的二氧化碳气氛下进行的。
作为本发明的进一步优选，所述步骤(3)中，所述溶剂为N，N-二甲基甲酰胺、二氯甲烷、丙酮、甲苯、以及四氢呋喃中的一种。
作为本发明的进一步优选，所述步骤(3)得到的所述聚丙撑碳酸酯/纤维素纳米晶复合材料中，所述聚丙撑碳酸酯的数均分子量为13.6～93.2kg/mol，所述聚丙撑碳酸酯的多分散性指数为1.08～1.2。
通过本发明所构思的以上技术方案，与现有技术相比，由于采用原位聚合反应制备聚丙撑碳酸酯/纤维素纳米晶复合材料，使得纤维素纳米晶均匀地分散在聚丙撑碳酸酯基体中，分散性好，有效避免纤维素纳米晶的团聚，从而提高复合材料中填料纤维素纳米晶的尺寸稳定性；本发明具体是先将纤维素纳米晶与环氧丙烷混合均匀得到分散液，再向该分散液中加入二氧化碳，在催化剂(优选还可包括助催化剂)的作用下，纤维素表面的羧基引发二氧化碳和环氧丙烷发生共聚合反应原位生成聚丙撑碳酸酯，得到聚丙撑碳酸酯/纤维素纳米晶复合材料；该复合材料的界面相容性好，纤维纳米晶均匀地分散在聚丙撑碳酸酯基体中，并且，由于纤维素纳米晶自身热学力学性能良好，可显著提升聚丙撑碳酸酯基体的力学和热学性能。
本发明是在高压二氧化碳气氛下进行的，二氧化碳的初始气压值优选为1～3MPa，通过控制二氧化碳的气压值，能够避免二氧化碳气压力过低或者过高对催化剂活性的影响(例如，使催化剂失活)。
本发明是在催化剂、以及助催化剂存在的条件下，进行原位聚合反应，催化剂能够使环氧丙烷和二氧化碳发生共聚合；而助催化剂对催化剂发挥其催化反应活性具有关键作用。本发明尤其通过利用具有特定化学式的金属席夫碱配合物催化剂或金属卟啉配合物催化剂(即具有如式I所示结构的金属席夫碱配合物催化剂、具有如式II所示结构的金属卟啉配合物催化剂)作为催化剂，并同时利用具有季鏻盐结构的助催化剂(尤其是如式III 所示结构的具有季鏻盐结构的物质)，通过它们之间、以及它们与其他反应原料(如环氧丙烷、纤维素纳米晶等)之间的整体配合，使得纤维素表面的羧基引发二氧化碳和环氧丙烷发生共聚合反应原位生成聚丙撑碳酸酯，得到聚丙撑碳酸酯/纤维素纳米晶复合材料。本发明尤其还通过控制原位聚合反应体系中各个原料物质的配比，优选使得纤维素纳米晶为环氧丙烷的0.5～10wt％，环氧丙烷与溶剂的摩尔比为1:1～1:5(溶剂能够使纤维素纳米晶分散得更加均匀)，催化剂与环氧丙烷的摩尔比为1:1000～1:8000，催化剂与助催化剂的摩尔比为1:1～1:10，利用各个反应原料之间的整体配合，使得原位聚合反应能够有效进行，得到的聚丙撑碳酸酯/纤维素纳米晶复合材料中填料纤维素纳米晶能够均匀分散于基体聚丙撑碳酸酯内，并且有效控制聚丙撑碳酸酯的数均分子量及多分散性指数。
本方法反应条件温和，重复性好，利用纤维素纳米晶在有机溶剂中的分散性能良好的特点，提高纤维素纳米晶作为填料在聚丙撑碳酸酯基体中的分散均匀性，而且还能提高纤维素纳米晶和聚丙撑碳酸酯的相容性，显著提高聚丙撑碳酸酯复合材料的力学性能和热稳定性能。
本发明的技术方案操作简单、反应条件温和，制备过程重复性好，制备成本低。并且，利用本发明制备得到的聚丙撑碳酸酯/纤维素纳米晶复合材料具有以下优点：
(1)聚丙撑碳酸酯/纤维素纳米晶复合材料为全生物降解高分子材料，生物相容性优良；
(2)纤维素纳米晶在聚丙撑碳酸酯基体中分散均匀，无团聚现象存在；
(3)聚丙撑碳酸酯包覆的纤维素纳米晶可以在有机溶剂中良好分散，能够长时间不沉降；
(4)纤维素纳米晶能改善聚丙撑碳酸酯基体材料的力学性能和热稳定性。
现有技术中绝大部分的催化体系在羧基存在的条件下会失去活性，不 能满足原位聚合的需求；本发明则是利用羧基化的纤维素纳米晶(如经过TEMPO氧化过的羧基化的纤维素纳米晶)作为反应原料，并通过选择具有特定化学结构式的催化剂(当然也包括与催化剂配合使用的助催化剂)，利用纤维素纳米晶表面的羧基引发二氧化碳和环氧化物的原位聚合反应，从而使得原位聚合反应能够顺利进行；此外，通过控制催化剂与单体的配比等其他反应条件及参数，可进一步优化产物。本发明尤其通过控制催化剂和助催化剂的种类、催化剂与单体的配比、反应温度和反应时间来控制聚合得到聚丙撑碳酸酯包覆的纤维素纳米晶，使得制备得到的聚丙撑碳酸酯/纤维素纳米晶复合材料中，聚丙撑碳酸酯的数均分子量为13.6～93.2kg/mol，所述聚丙撑碳酸酯的多分散性指数为1.08～1.2。
【附图说明】
图1是实施例1制备的聚丙撑碳酸酯包覆的纤维素纳米晶的透射电镜图(图中比例尺代表0.5μm)。
图2是实施例2制备的聚丙撑碳酸酯包覆的纤维素纳米晶的红外光谱图。从图中可以看到聚丙撑碳酸酯包覆的纤维素纳米晶在1740cm -1(C＝0)，1246cm -1(C-O)表现出聚丙撑碳酸酯的特征红外吸收峰。
图3是实施例3制备的聚丙撑碳酸酯包覆的纤维素纳米晶的热失重分析曲线。从图中可以看出聚丙撑碳酸酯包覆的纤维素纳米晶的热分解温度明显高于纤维素纳米晶和聚丙撑碳酸酯。
图4是实施例4制备的聚丙撑碳酸酯/纤维素纳米晶的扫描电镜图。图中白色的点代表的是被聚丙撑碳酸酯包覆的纤维素纳米晶；从图中可以看到聚丙撑碳酸酯包覆的纤维素纳米晶能均匀分散在聚丙撑碳酸酯基体中。
【具体实施方式】
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。此外，下面所描述的 本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。
本发明聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，是采用原位共聚合方法制备得到聚丙撑碳酸酯；聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，具体可包括如下步骤：
(1)在保护性气体(如氮气或惰性气体)的保护下，将纤维素纳米晶(尤其是羧基化纤维素纳米晶)、环氧丙烷、催化剂、助催化剂、溶剂加入到高压反应釜，得到环氧丙烷和纤维素纳米晶混合液；
(2)将高压反应釜置于冰浴条件(如0～10℃温度)下，在搅拌作用下，将步骤(1)得到的环氧丙烷和纤维素纳米晶混合液混合均匀，得到环氧丙烷和纤维素纳米晶分散液；
(3)向步骤(2)得到的环氧丙烷和纤维素纳米晶分散液中通入二氧化碳，在密封的高压条件下，在20～120℃下原位聚合反应5～25小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物；
(4)将步骤(3)得到的聚丙撑碳酸酯包覆的纤维素纳米晶混合物用溶剂稀释，以除去催化剂和未反应的单体；
(5)将步骤(4)的聚丙撑碳酸酯包覆的纤维素纳米晶溶液用甲醇沉淀、干燥，进一步除去催化剂和未反应的单体，从而制得聚丙撑碳酸酯/纤维素纳米晶复合材料。
其中，步骤(1)所采用的催化剂可选自金属席夫碱配合物催化剂或金属卟啉配合物催化剂，金属席夫碱配合物催化剂具有式(I)所示结构；金属卟啉配合物催化剂具有式(II)所示结构：
Figure PCTCN2018080765-appb-000004
R 1，R 2，R 3，R 4，R 5，R 6各自独立的选自：H，卤素，C 1-C 20的烷基，C 1-C 20的烷氧基，氟取代的烷基，氟取代的芳基中的一种。更优选的R 1，R 2，R 3，R 4，R 5，R 6各自独立的选自氢、卤素；优选的，X选自Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO、对甲基苯磺酸根、邻硝基苯酚氧、对硝基苯酚氧、间硝基苯酚氧、2，4-二硝基苯酚氧、3，5-二硝基苯酚氧、2，4，6-三硝基苯酚氧、3，5-二氯苯酚氧、3，5-二氟苯酚氧、3，5-二-三氟甲基苯酚氧或五氟酚氧负离子中的一种。更优选的X选自Cl、N 3、ClO 4、BF 4、NO 3；M选自Mg，Co，Zn，Cr，Al中的一种，更优选的M选自Co，Al中的一种。
此外，步骤(1)所采用的助催化剂为季鏻盐结构的物质，选自式(III)中的一种，
Figure PCTCN2018080765-appb-000005
式(III)中，Y为Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO、邻硝基苯酚氧、对硝基苯酚氧、间硝基苯酚氧、2，4-二硝基苯酚氧、3，5-二硝基苯酚氧、2，4，6-三硝基苯酚氧、3，5-二氯苯酚氧、3，5-二氟苯酚氧、3，5-二-三氟甲基苯酚氧或五氟酚氧负离子中的一种；更优选式(III)中Y为Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO。
以下为具体实施例：
实施例1
在氮气保护的条件下，分别将40mg羧酸化纤维素纳米晶，0.04mmol具有式II所示结构的催化剂(其中，R 2＝H，R 3＝CH 3，R 4＝Cl，R 5＝OCH 2CH 3，R 6＝H，M＝Co，X＝邻硝基苯酚氧)，0.04mmol具有式III所示结构的助催化剂(其中，Y＝邻硝基苯酚氧)，40mmol环氧丙烷，40mmol二氯甲烷加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以400rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中(二氧化碳的压力是指分散液中的二氧化碳已经溶解了以后的初始平衡压力；即，向高压反应釜内通入特定压力的二氧化碳，当分散液中溶解的二氧化碳达到饱和时，高压反应釜内的二氧化碳气压将保持稳定，保持稳定的二氧化碳气压即对应初始平衡压力)，在20℃下原位聚合反应12小时后，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合 物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用二氯甲烷稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为0.5wt％，其聚丙撑碳酸酯的数均分子量为13.6kg/mol，聚丙撑碳酸酯的多分散性指数为1.08。
实施例1制得的聚丙撑碳酸酯改性纤维素纳米晶的透射电镜图片见图1。
实施例2
在氮气保护的条件下，分别将80mg羧酸化纤维素纳米晶，0.02mmol具有式II所示结构的催化剂(其中，R 2＝H，R 3＝CH 2CH 3，R 4＝CF 2CF 3，R 5＝OCH 2CH 2CH 3，R 6＝C 6F 5，M＝Al，X＝对硝基苯酚氧)，0.2mmol具有式III所示结构的助催化剂(其中，Y＝对硝基苯酚氧)，40mmol环氧丙烷，200mmolN，N-二甲基甲酰胺加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以100rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在120℃下原位聚合反应20小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用N，N-二甲基甲酰胺稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为1wt％，其聚丙撑碳酸酯的数均分子量为19.1kg/mol，聚丙撑碳酸酯的多分散性指数为1.10。
实施例2制得的聚丙撑碳酸酯改性纤维素纳米晶的红外图谱见图2。
实施例3
在氮气保护的条件下，分别将120mg羧酸化纤维素纳米晶，0.01mmol具有式I所示结构的催化剂(其中，R 1＝H，M＝Co，X＝Cl)，0.04mmol具 有式III所示结构的助催化剂(其中，Y＝Cl)，40mmol环氧丙烷，80mmol四氢呋喃加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在25℃下原位聚合反应18小时后，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用四氢呋喃稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为1.5wt％，其聚丙撑碳酸酯的数均分子量为34.1kg/mol，聚丙撑碳酸酯的多分散性指数为1.09。实施例3制备的聚丙撑碳酸酯包覆的纤维素纳米晶的热失重分析曲线见图3
实施例4
在氮气保护的条件下，分别将160mg羧酸化纤维素纳米晶，0.01mmol具有式I所示结构的催化剂(其中，R 1＝Cl，M＝Zn，X＝BF 4)，0.06mmol具有式III所示结构的助催化剂(其中，Y＝BF 4)，40mmol环氧丙烷，100mmol丙酮加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以100rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在25℃下原位聚合反应20小时后，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用丙酮稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为2wt％，其聚丙撑碳酸酯的数均分子量为32.1kg/mol，聚丙撑碳酸酯的多分散性指数为1.12。实施例4制备得到的聚丙撑碳酸酯/纤维素纳米晶复合材料其扫描电镜图如图4所示。
实施例5
在氮气保护的条件下，分别将200mg羧酸化纤维素纳米晶，0.01mmol具有式I所示结构的催化剂(其中，R 1＝CH 2CH 3，M＝Mg，X＝N 3)，0.08mmol具有式III所示结构的助催化剂(其中，Y＝N 3)，40mmol环氧丙烷，100mmol丙酮加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以200rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在20℃下原位聚合反应25小时，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用丙酮稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为2.5wt％，其聚丙撑碳酸酯的数均分子量为32.6kg/mol，聚丙撑碳酸酯的多分散性指数为1.14。
实施例6
在氮气保护的条件下，分别将240mg羧酸化纤维素纳米晶，0.01mmol具有式I所示结构的催化剂(其中，R 1＝OCH 2CH 3，M＝Al，X＝NO 3)，0.01mmol具有式III所示结构的助催化剂(其中，Y＝NO 3)，40mmol的环氧丙烷，80mmol丙酮加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在50℃下原位聚合反应20小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用丙酮稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为3wt％，其聚丙撑碳酸酯的数均分子量为33.6kg/mol，聚丙撑碳酸酯的多分散性指数为1.12。
实施例7
在氮气保护的条件下，分别将280mg羧酸化纤维素纳米晶，0.01mmol具有式I所示结构的催化剂(其中，R 1＝CF 3，M＝Cr，X＝ClO 4)，0.04mmol具有式III所示结构的助催化剂(其中，Y＝ClO 4)，40mmol环氧丙烷，80mmol丙酮加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以500rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在25℃下原位聚合反应18小时后，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用丙酮稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为3.5wt％，其聚丙撑碳酸酯的数均分子量为32.4kg/mol，聚丙撑碳酸酯的多分散性指数为1.10。
实施例8
在氮气保护的条件下，分别将320mg羧酸化纤维素纳米晶，0.01mmol具有式I所示结构的催化剂(其中，R 1＝C 6F 5，M＝Cr，X＝CH 3COO)，0.01mmol具有式III所示结构的助催化剂(其中，Y＝CH 3COO)，40mmol环氧丙烷，80mmol N，N-二甲基甲酰胺加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在40℃下原位聚合反应25小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用N，N-二甲基甲酰胺稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为4wt％，其聚丙撑碳酸酯的数均分子量为31.5kg/mol，聚丙撑碳酸酯的多分散性指数为1.14。
实施例9
在氮气保护的条件下，分别将360mg羧酸化纤维素纳米晶,0.01mmol具有式I所示结构的催化剂(其中，R 1＝CH 2CH 2CH 3，M＝Co，X＝CCl 3COO)，0.01mmol具有式III所示结构的助催化剂(其中，Y＝CCl 3COO)，40mmol环氧丙烷，200mmol甲苯加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在70℃下原位聚合反应20小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用甲苯稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为4.5wt％，其聚丙撑碳酸酯的数均分子量为31.4kg/mol，聚丙撑碳酸酯的多分散性指数为1.08。
实施例10
在氮气保护的条件下，分别将400mg羧酸化纤维素纳米晶，0.01mmol具有式I所示结构的催化剂(其中，R 1＝H，M＝Al，X＝邻硝基苯酚氧)，0.1mmol具有式III所示结构的助催化剂(其中，Y＝邻硝基苯酚氧)，40mmol环氧丙烷，200mmol甲苯加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在80℃下原位聚合反应25小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用甲苯稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为5wt％，其聚丙撑碳酸酯的数均分子量为30.4kg/mol，聚丙撑碳酸酯的多分散性指数为1.05。
实施例11
在氮气保护的条件下，分别将400mg羧酸化纤维素纳米晶，0.005mmol具有式II所示结构的催化剂(其中，R 2＝C 6F 5，R 3＝Br，R 4＝CF 3，R 5＝OCH 2CH 3，R 6＝H，M＝Mg，X＝间硝基苯酚氧)，0.025mmol具有式III所示结构的助催化剂(其中，Y＝间硝基苯酚氧)，40mmol环氧丙烷，200mmol N，N-二甲基甲酰胺加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以500rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在120℃下原位聚合反应25小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用N，N-二甲基甲酰胺稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为5wt％，其聚丙撑碳酸酯的数均分子量为93.2kg/mol，聚丙撑碳酸酯的多分散性指数为1.2。
实施例12
在氮气保护的条件下，分别将400mg羧酸化纤维素纳米晶，0.005mmol具有式II所示结构的催化剂(其中，R 2＝C 6F 5，R 3＝F，R 4＝CF 3，R 5＝OCH 2CH 3，R 6＝F，M＝Zn，X＝2，4-二硝基苯酚氧)，0.005mmol具有式III所示结构的助催化剂(其中，Y＝2，4-二硝基苯酚氧)，40mmol环氧丙烷，80mmol N，N-二甲基甲酰胺加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以400rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在110℃下原位聚合反应20小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用N，N-二甲基甲酰胺稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得 聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为5wt％，其聚丙撑碳酸酯的数均分子量为92.7kg/mol，聚丙撑碳酸酯的多分散性指数为1.18。
实施例13
在氮气保护的条件下，分别将400mg羧酸化纤维素纳米晶，0.005mmol具有式II所示结构的催化剂(其中，R 2＝F，R 3＝C 6F 5，R 4＝H，R 5＝OCH 3，R 6＝F，M＝Cr，X＝3，5-二硝基苯酚氧)，0.05mmol具有式III所示结构的助催化剂(其中，Y＝3，5-二硝基苯酚氧)，40mmol环氧丙烷，200mmol甲苯加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以500rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在100℃下原位聚合反应16小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用甲苯稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为5wt％，其聚丙撑碳酸酯的数均分子量为91.8kg/mol，聚丙撑碳酸酯的多分散性指数为1.16。
实施例14
在氮气保护的条件下，分别将400mg羧酸化纤维素纳米晶，0.005mmol具有式II所示结构的催化剂(其中，R 2＝F，R 3＝C 6F 5，R 4＝H，R 5＝OCH 3，R 6＝F，M＝Cr，X＝2，4，6-三硝基苯酚氧)，0.005mmol具有式III所示结构的助催化剂(其中，Y＝2，4，6-三硝基苯酚氧)，40mmol环氧丙烷，200mmol甲苯加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在100℃下原位聚合反应18小时后，冷却到室温，释放高压反应釜内 的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用甲苯稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为5wt％，其聚丙撑碳酸酯的数均分子量为91.0kg/mol，聚丙撑碳酸酯的多分散性指数为1.12。
实施例15
在氮气保护的条件下，分别将400mg羧酸化纤维素纳米晶，0.005mmol具有式II所示结构的催化剂(其中，R 2＝F，R 3＝C 6F 5，R 4＝H，R 5＝OCH 3，R 6＝F，M＝Cr，X＝3，5-二氯苯酚氧)，0.02mmol具有式III所示结构的助催化剂(其中，Y＝3，5-二氯苯酚氧)，40mmol环氧丙烷，200mmol甲苯加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在90℃下原位聚合反应20小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用甲苯稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为5wt％，其聚丙撑碳酸酯的数均分子量为90.8kg/mol，聚丙撑碳酸酯的多分散性指数为1.15。
实施例16
在氮气保护的条件下，分别将400mg羧酸化纤维素纳米晶，0.005mmol具有式II所示结构的催化剂(其中，R 2＝F，R 3＝C 6F 5，R 4＝H，R 5＝OCH 3，R 6＝F，M＝Cr，X＝3，5-二氟苯酚氧)，0.05mmol具有式III所示结构的助催化剂(其中，Y＝3，5-二氟苯酚氧)，40mmol环氧丙烷，80mmol N，N-二甲基甲酰胺加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙 烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在85℃下原位聚合反应21小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用N，N-二甲基甲酰胺稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为5wt％，其聚丙撑碳酸酯的数均分子量为92.4kg/mol，聚丙撑碳酸酯的多分散性指数为1.20。
实施例17
在氮气保护的条件下，分别将400mg羧酸化纤维素纳米晶，0.005mmol具有式II所示结构的催化剂(其中，R 2＝F，R 3＝C 6F 5，R 4＝H，R 5＝OCH 3，R 6＝F，M＝Cr，X＝3，5-二-三氟甲基苯酚氧)，0.01mmol具有式III所示结构的助催化剂(其中，Y＝3，5-二-三氟甲基苯酚氧)，40mmol环氧丙烷，200mmol甲苯加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在80℃下原位聚合反应20小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用甲苯稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为5wt％，其聚丙撑碳酸酯的数均分子量为91.4kg/mol，聚丙撑碳酸酯的多分散性指数为1.16。
实施例18
在氮气保护的条件下，分别将320mg羧酸化纤维素纳米晶，0.01mmol具有式II所示结构的催化剂(其中，R 2＝F，R 3＝C 6F 5，R 4＝H，R 5＝OCH 3，R 6＝F，M＝Cr，X＝五氟酚氧负离子)，0.05mmol具有式III所示结构的助催 化剂(其中，Y＝五氟酚氧负离子)，40mmol环氧丙烷，200mmol甲苯加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以500rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将3MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在90℃下原位聚合反应22小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用甲苯稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为4wt％，其聚丙撑碳酸酯的数均分子量为30.8kg/mol，聚丙撑碳酸酯的多分散性指数为1.12。
实施例19
在氮气保护的条件下，分别将320mg羧酸化纤维素纳米晶，0.01mmol具有式I所示结构的催化剂(其中，R 1＝H，M＝Cr，X＝对甲基苯磺酸根)，0.01mmol具有式III所示结构的助催化剂(其中，Y＝Cl)，40mmol环氧丙烷，80mmol二氯甲烷加入高压反应釜，得到环氧丙烷和纤维素纳米晶混合液。将高压反应釜置于冰浴条件下以600rpm/min的条件下混合均匀，得到环氧丙烷和纤维素纳米晶分散液。将2MPa的二氧化碳通入环氧丙烷和纤维素纳米晶分散液中，在25℃下原位聚合反应20小时后，冷却到室温，释放高压反应釜内的二氧化碳，得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物，将聚丙撑碳酸酯包覆的纤维素纳米晶混合物用二氯甲烷稀释，然后将聚丙撑碳酸酯包覆的的纤维素纳米晶溶液用甲醇沉淀、干燥，制得聚丙撑碳酸酯/纤维素纳米晶复合材料。其中纤维素纳米晶含量为4wt％，其聚丙撑碳酸酯的数均分子量为29.6kg/mol，聚丙撑碳酸酯的多分散性指数为1.2。
上述实施例制得的聚丙撑碳酸酯/纤维素纳米晶复合材料，其力学性能及热稳定性均有大幅提高。通过透射电镜图图1可以看出，纤维素纳米晶被聚丙撑碳酸酯包覆，且均匀分散；通过热失重分析曲线图3可以看出， 聚丙撑碳酸酯包覆的纤维素纳米晶的热分解温度明显高于普通的纤维素纳米晶和聚丙撑碳酸酯，说明聚丙撑碳酸酯包覆的纤维素其纤维素纳米晶和聚丙撑碳酸酯具有很强的界面作用力，且能很好的分散，其力学和热学性能必然大幅提高。通过扫描电镜图图4可以看出，其中聚丙撑碳酸酯包覆的纤维素纳米晶在聚丙撑碳酸酯能均匀分散。可见，基体内的纤维素纳米晶分散性好，有效避免了颗粒间的团聚，使得填料纤维素纳米晶在复合材料中尺寸稳定性也会相应提高。
本发明所采用的各种试剂均可由市售购得，或者可自行采用现有技术中记载的制备方法制备得到。本发明中所采用的羧基化纤维素纳米晶，可以采用现有技术的常规方法对市售购得的纤维素纳米晶进行羧基化处理，羧基化处理可采用常规的处理工艺，纤维素纳米晶表面的羧基接枝情况，对纤维素纳米晶的添加比例、以及后续聚合反应没有影响，只要羧基存在即可；例如，TEMPO氧化纤维素纳米晶的处理工艺可参考参考文献Biomacromolecules 2004,5,1983-1989。
本领域的技术人员容易理解，以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (9)

  1. 一种聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，包括以下步骤：
    (1)在保护性气体的保护下，将纤维素纳米晶、环氧丙烷、催化剂、助催化剂、以及溶剂混合得到环氧丙烷/纤维素纳米晶混合液；接着，将所述环氧丙烷/纤维素纳米晶混合液在冰浴条件下进行搅拌，得到混合均匀的环氧丙烷/纤维素纳米晶分散液；
    (2)向所述步骤(1)得到的所述环氧丙烷/纤维素纳米晶分散液中通入二氧化碳，然后在密封环境下于20～120℃下进行原位聚合反应5～25小时，使得所述环氧丙烷/纤维素纳米晶分散液在二氧化碳气氛下进行原位聚合反应得到聚丙撑碳酸酯包覆的纤维素纳米晶混合物；
    (3)用溶剂稀释所述步骤(2)得到的所述聚丙撑碳酸酯包覆的纤维素纳米晶混合物，得到聚丙撑碳酸酯包覆的纤维素纳米晶溶液；接着，对该聚丙撑碳酸酯包覆的纤维素纳米晶溶液用甲醇沉淀，然后干燥，即得到聚丙撑碳酸酯/纤维素纳米晶复合材料。
  2. 如权利要求1所述聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，所述步骤(1)中，所述纤维素纳米晶为羧基化纤维素纳米晶；所述纤维素纳米晶为所述环氧丙烷的0.5～10wt％。
  3. 如权利要求1所述聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，所述步骤(1)中，所述催化剂选自金属席夫碱配合物催化剂、以及金属卟啉配合物催化剂中的任意一种；
    其中，所述金属席夫碱配合物催化剂具有如式(I)所示结构：
    Figure PCTCN2018080765-appb-100001
    Figure PCTCN2018080765-appb-100002
    该式(I)中，R 1为H、卤素、C 1-C 20的烷基、C 1-C 20的烷氧基、氟取代的C 1-C 20的烷基、以及氟取代的芳基中的任意一种；X选自Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO、对甲基苯磺酸根、邻硝基苯酚氧、对硝基苯酚氧、间硝基苯酚氧、2，4-二硝基苯酚氧、3，5-二硝基苯酚氧、2，4，6-三硝基苯酚氧、3，5-二氯苯酚氧、3，5-二氟苯酚氧、3，5-二-三氟甲基苯酚氧、以及五氟酚氧负离子中的任意一种；M选自Mg、Co、Zn、Cr、以及Al中的任意一种；
    所述金属卟啉配合物催化剂具有如式(II)所示结构：
    Figure PCTCN2018080765-appb-100003
    该式(II)中，R 2、R 3、R 4、R 5、R 6各自独立的选自H、卤素、C 1-C 20的烷基、C 1-C 20的烷氧基、氟取代的C 1-C 20的烷基、以及氟取代的芳基中的任意一种；X选自Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO、对甲基苯磺酸根、邻硝基苯酚氧、对硝基苯酚氧、间硝基苯酚氧、2，4-二硝基苯酚氧、3，5-二硝基苯酚氧、2，4，6-三硝基苯酚氧、3，5-二氯苯酚氧、3，5-二氟苯酚氧、3，5-二-三氟甲基苯酚氧、以及五氟酚氧负离子中的任意一种；M选自Mg、Co、Zn、Cr、以及Al中的任意一种；
    此外，所述催化剂与所述环氧丙烷的摩尔比为1:1000～1:8000。
  4. 如权利要求1所述聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，所述步骤(1)中，所述助催化剂为具有季鏻盐结构的物质，优选的，所述助催化剂具有如式(III)所示结构：
    Figure PCTCN2018080765-appb-100004
    该式(III)中，Y为Cl、N 3、ClO 4、BF 4、NO 3、CH 3COO、CCl 3COO、邻硝基苯酚氧、对硝基苯酚氧、间硝基苯酚氧、2，4-二硝基苯酚氧、3，5-二硝基苯酚氧、2，4，6-三硝基苯酚氧、3，5-二氯苯酚氧、3，5-二氟苯酚氧、3，5-二-三氟甲基苯酚氧、以及五氟酚氧负离子中的任意一种；
    所述催化剂与所述助催化剂的摩尔比为1:1～1:10。
  5. 如权利要求1所述聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，所述步骤(1)中，所述溶剂为N，N-二甲基甲酰胺、二氯甲烷、丙酮、甲苯、以及四氢呋喃中的任意一种；所述环氧丙烷与所述溶剂的摩尔比为1:1～1:5。
  6. 如权利要求1所述聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，所述步骤(1)中，所述搅拌所采用的搅拌速度为100～600rpm/min。
  7. 如权利要求1所述聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，所述步骤(2)中，所述原位聚合反应是在初始二氧化碳的压力为1～3MPa的二氧化碳气氛下进行的。
  8. 如权利要求1-7任意一项所述聚丙撑碳酸酯/纤维素纳米晶复合材 料的制备方法，其特征在于，所述步骤(3)中，所述溶剂为N，N-二甲基甲酰胺、二氯甲烷、丙酮、甲苯、以及四氢呋喃中的一种。
  9. 如权利要求1-8任意一项所述聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法，其特征在于，所述步骤(3)得到的所述聚丙撑碳酸酯/纤维素纳米晶复合材料中，所述聚丙撑碳酸酯的数均分子量为13.6～93.2kg/mol，所述聚丙撑碳酸酯的多分散性指数为1.08～1.2。
PCT/CN2018/080765 2017-07-13 2018-03-28 一种聚丙撑碳酸酯/纤维素纳米晶复合材料的制备方法 Ceased WO2019011009A1 (zh)

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