Preparation method of xylose-based thermoplastic polyester elastomer

Abstract

The invention discloses a preparation method of a xylose-based thermoplastic polyester elastomer, which comprises the following steps: (1) taking D-xylose and glyoxylic acid as raw materials, and synthesizing xylose diglyoxylate DGAX through condensation reaction under the catalytic condition of concentrated sulfuric acid; (2) adding a large amount of methanol to directly esterify the xylose diglyoxylate to generate xylose diglyoxylate DMGX with a mixed configuration; and (3) synthesizing a PEDX homopolymer, namely the xylose-based thermoplastic polyester elastomer, by taking the diglyoxylate xylose DMGX with the mixed configuration and diol as raw materials through a transesterification-melt polycondensation two-step method in the presence of a catalyst. The thermoplastic polyester elastomer with a wide use temperature range is prepared by directly polymerizing the bifunctional xylose derivative, so that the simple and efficient preparation of a biomass material is realized.

Description

Technical Field

[0001] This invention relates to the field of compound synthesis technology, and in particular to a method for preparing a xylose-based thermoplastic polyester elastomer. Background Technology

[0002] Thermoplastic polyester elastomers (TPEEs) are an important class of synthetic materials. They possess both the high elasticity of rubber and the ability to be repeatedly processed at high temperatures, and are widely used in wires and cables, hoses, and shock absorbers. TPEEs typically consist of aromatic polyester hard segments and polyether or aliphatic polyester soft segments. The molecular chains of the hard segments form reversible physical cross-linking points through non-covalent bonds or entanglement, ensuring the material's rigidity and strength, while the flexible soft segments provide the material's elastic properties. In the early 1870s, DuPont introduced the polyester elastomer Hytel, whose hard and soft segments were composed of polybutylene terephthalate (PBT) and poly(tetramethylene glycol) (PTMG), respectively, with a melting point (T... m Its temperature range is 230 °C, and it exhibits excellent crystallinity. With the introduction of sustainable development goals, there is a growing expectation to develop TPEE based on biomass resources to replace traditional petroleum-based elastomer materials. Polylactic acid (PLA) is a semi-crystalline polymer with a temperature range of 230 °C. g and T m The temperatures are approximately 65 and 170 °C, respectively, which can be used as the hard segment of TPEE. For example, Hillmyer et al. (Watts A, Kurokawa N, Hillmyer M A. Strong, resilient, and sustainable aliphatic polyesterthermoplastic elastomers. Biomacromolecules 2017, 18: 1845-1854) prepared a biomass TPEE with PLA as the hard segment and poly(γ-methyl-ε-caprolactone) (PγMCL) as the soft segment via transesterification polymerization. The results showed that when the PLA content was 17%, the elongation at break and the maximum tensile strength of the elastomer were approximately 1029% and 24 MPa, respectively, and the T values ​​of the hard and soft segments were also high. g The temperatures were 42 and -60 °C, respectively. However, PLA had a relatively low T... gThe inability to fully meet the application requirements of TPEE has limited the further development of PLA-based TPEE. Therefore, researchers have turned their attention to biomass monomers with rigid cyclic structures, such as 2,5-furandicarboxylic acid (FDCA), a biomass monomer with structures and properties similar to petroleum-based aromatic terephthalic acid. Semi-crystalline polydialkyl furanate esters prepared from FDCA and its esters typically exhibit high TT (total crystalline content). g and T m It can serve as the hard segment of TPEE and form a well-separated microphase structure with the flexible soft segment. For example, Liu and Na et al. (Chi D, Liu F, Na H, Chen J, Hao C, Zhu J. Poly(neopentyl glycol 2,5-furandicarboxylate): a promising hard segment for the development of bio-based thermoplastic poly(ether-ester) elastomer with high performance. ACSSustainable Chem. Eng. 2018, 6: 9893-9902) first synthesized the hard segment of the elastomer using neopentyl glycol and 2,5-furandicarboxylate as raw materials via transesterification, and then introduced PTMG as the soft segment via melt polycondensation to finally prepare furan-based TPEE. Depending on the content of the hard segment, the T of the elastomer... m The maximum temperature can reach 180 °C, with a maximum tensile strength of 34 MPa and an elongation at break of 38%. Clearly, introducing biomass monomers with rigid cyclic structures into the TPEE system can not only reduce dependence on petrochemical resources but also potentially endow it with thermodynamic properties similar to traditional petroleum-based TPEEs. Although FDCA is a highly promising class of biomass monomers, its conversion process remains relatively complex, involving the following steps: first, cellulose is extracted from biomass resources, then depolymerized to produce glucose, isomerized to produce fructose, dehydrated to produce 5-hydroxymethylfurfural, and finally oxidized to produce FDCA. According to incomplete statistics, the current price of FDCA (approximately 10 RMB / g, data from Beijing Innocare Technology Co., Ltd.) is still relatively high compared to the price of terephthalic acid (approximately 0.5 RMB / g), which to some extent limits the development of furanyl TPEEs. Therefore, developing rigid cyclic biomass monomers with fewer chemical conversion and purification steps is of great significance. Summary of the Invention

[0003] Therefore, the present invention provides a method for preparing a xylose-based thermoplastic polyester elastomer, comprising the following steps: (1) D-xylose and glyoxylic acid were used as raw materials to synthesize xylose diglyoxylate (DGAX) by condensation reaction under concentrated sulfuric acid catalysis. (2) Add a large amount of methanol to directly esterify xylose diglyoxylate to generate xylose diglyoxylate DMGX with mixed configuration; (3) Using the mixed configuration of xylose diglyoxalate DMGX and diol as raw materials, PEDX homopolymer is synthesized in a two-step process of transesterification-melt polycondensation under catalytic conditions, which is the xylose-based thermoplastic polyester elastomer.

[0004] Furthermore, in step (3), polytetramethylene ether glycol of different mass fractions is added to the raw materials, and multi-block copolymer PEDX-yPTMG is synthesized by a two-step method of transesterification-melt polycondensation under the conditions of tetrabutyl titanate catalyst.

[0005] Further, the mixed-configuration xylose diglyoxylate DMGX is separated into two different configurations by column chromatography. Then, the two different configurations of xylose diglyoxylate DMGX in step (3) are replaced with the two different configurations of xylose diglyoxylate as raw materials, and homopolymers are synthesized by a two-step transesterification-melt polycondensation method under tetrabutyl titanate catalyst conditions.

[0006] Further, in step (1), the mass ratio of D-xylose, glyoxylic acid and concentrated sulfuric acid is D-xylose:glyoxylic acid:concentrated sulfuric acid = 20:50:3; the condensation reaction temperature is 90±5℃, and the reaction environment pressure is 30~50mbar.

[0007] Further, in step (3), the mass ratio of diglyoxylate xylose DMGX to ethylene glycol is diglyoxylate xylose: ethylene glycol = 2.8~3: 0.38~0.55.

[0008] Furthermore, in step (3), the mass percentage of polytetramethylene ether glycol in the raw materials is 0.01% to 99%.

[0009] Further, in step (3), the catalyst is tetrabutyl titanate, zinc acetate or antimony trioxide; the mass of the catalyst added is 0.05 wt% of the xylose diglyoxylate in the raw material.

[0010] Furthermore, in step (3), the diol is ethylene glycol.

[0011] Furthermore, in step (3), the reaction temperature of the first step is 130±5℃ and the reaction time is 2 to 3 hours, and the reaction temperature of the second step is 145±5℃ and the reaction time is 3 to 4 hours.

[0012] The beneficial effects of this invention are as follows: Using renewable xylose as raw material, this invention prepares polymerizable xylose monomer DMGX via a one-pot process, and then polymerizes it with diol and PTMG in a two-step process of transesterification-melt polycondensation to prepare a multi-block copolymer xylose-based TPEE. The direct polymerization of bifunctional xylose derivatives yields thermoplastic polyester elastomers with a wide operating temperature range, thus achieving simple and efficient preparation of biomass materials. Introducing rigid cyclic biomass building blocks into the TPEE system reduces dependence on petrochemical resources and lays the foundation for the design, synthesis, and modification of novel biomass polymer materials. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the reaction mechanism described in this invention; Figure 2 A schematic diagram of the thermal decomposition of a xylose-based thermoplastic polyester elastomer, PEDX-50PTMG. Figure 3 Differential scanning calorimetry (DSC) curves of PEDX-50PTMG, a xylose-based thermoplastic polyester elastomer. Detailed Implementation

[0014] The mechanism of this invention is as follows: Synthetic routes for xylose-based homopolymers and copolymers are as follows: Figure 1 As shown, firstly, xylose diglyoxylate (DGAX) was synthesized from D-xylose and glyoxylic acid via a condensation reaction under concentrated sulfuric acid catalysis. Next, a large amount of methanol was added to directly esterify the xylose diglyoxylate to generate a mixed-configuration xylose diglyoxylate (DMGX). This serves two purposes: firstly, to improve the reactivity of the xylose monomer in the condensation polymerization reaction, and secondly, to prevent decarboxylation of the carboxyl group at high temperatures. Finally, using the mixed-configuration DMGX, ethylene glycol (EG), and different mass fractions of PTMG as raw materials, a multi-block copolymer PEDX-yPTMG was synthesized via a two-step transesterification-melt polycondensation method under catalytic conditions, where y represents the mass percentage of PTMG. Alternatively, PEDX homopolymers can be synthesized using the same method without adding PTMG monomer. Two different configurations of xylose diglyoxylate, DMGX1 and DMGX2, were separated by column chromatography. Using the above polymerization method, homopolymers PDMGX1 and PDMGX2, as well as multiblock copolymers PEDX1-yPTMG and PEDX2-yPTMG, can be synthesized from DMGX1 and DMGX2, respectively.

[0015] The present invention will be further described below with reference to the embodiments.

[0016] A method for preparing a xylose-based thermoplastic polyester elastomer, comprising the following steps: (1) D-xylose and glyoxylic acid were used as raw materials to synthesize diglyoxylic acid xylose (DGAX) by condensation reaction under concentrated sulfuric acid catalysis; the condensation reaction temperature was 90℃ and the reaction environment pressure was 40mbar.

[0017] (2) Add a large amount of methanol to directly esterify xylose diglyoxylate to generate xylose diglyoxylate DMGX with mixed configuration; (3) Using 2.9g of diglyoxylate xylose (DMGX) with a mixed configuration, 0.55g of ethylene glycol, and 1.08g of polytetramethylene ether glycol (PTMG) as raw materials, a multi-block copolymer PEDX-yPTMG (y represents the mass percentage of PTMG) was synthesized via a two-step transesterification-melt polycondensation method under catalytic conditions; this is the xylose-based thermoplastic polyester elastomer; the yield is above 90%, wherein the first step reaction temperature is 130℃ and the reaction time is 2h, and the second step reaction temperature is 145℃ and the reaction time is 3h; the catalyst is tetrabutyl titanate; the mass of the catalyst added is 0.05wt% of the diglyoxylate xylose in the raw materials. The reaction formula is as follows. Figure 1 As shown.

[0018] Example 2 A method for preparing a xylose-based thermoplastic polyester elastomer, comprising the following steps: (1) D-xylose and glyoxylic acid were used as raw materials to synthesize diglyoxylic acid xylose (DGAX) by condensation reaction under concentrated sulfuric acid catalysis; the condensation reaction temperature was 90℃ and the reaction environment pressure was 40mbar.

[0019] (2) Add a large amount of methanol to directly esterify xylose diglyoxylate to generate xylose diglyoxylate DMGX with mixed configuration; (3) Using 2.9g of diglyoxylate xylose (DMGX) with a mixed configuration, 0.53g of ethylene glycol, and 1.54g of polytetramethylene ether glycol (PTMG) as raw materials, a multi-block copolymer PEDX-yPTMG (y represents the mass percentage of PTMG) was synthesized via a two-step transesterification-melt polycondensation method under catalytic conditions; this is the xylose-based thermoplastic polyester elastomer; the yield is above 90%, wherein the first step reaction temperature is 130℃ and the reaction time is 2h, and the second step reaction temperature is 145℃ and the reaction time is 3h; the catalyst is tetrabutyl titanate; the mass of the catalyst added is 0.05wt% of the diglyoxylate xylose in the raw materials. The reaction formula is as follows. Figure 1 As shown.

[0020] Example 3 A method for preparing a xylose-based thermoplastic polyester elastomer, comprising the following steps: (1) D-xylose and glyoxylic acid were used as raw materials to synthesize diglyoxylic acid xylose (DGAX) by condensation reaction under concentrated sulfuric acid catalysis; the condensation reaction temperature was 90℃ and the reaction environment pressure was 40mbar.

[0021] (2) Add a large amount of methanol to directly esterify xylose diglyoxylate to generate xylose diglyoxylate DMGX with mixed configuration; (3) Using 2.9g of diglyoxylate xylose (DMGX) with a mixed configuration, 0.49g of ethylene glycol, and 2.14g of polytetramethylene ether glycol (PTMG) as raw materials, a multi-block copolymer PEDX-yPTMG (y represents the mass percentage of PTMG) was synthesized via a two-step transesterification-melt polycondensation method under catalytic conditions; this is the xylose-based thermoplastic polyester elastomer; the yield is above 90%, wherein the first step reaction temperature is 130℃ and the reaction time is 2h, and the second step reaction temperature is 145℃ and the reaction time is 3h; the catalyst is tetrabutyl titanate; the mass of the catalyst added is 0.05wt% of the diglyoxylate xylose in the raw materials. The reaction formula is as follows. Figure 1 As shown.

[0022] Example 4 A method for preparing a xylose-based thermoplastic polyester elastomer, comprising the following steps: (1) D-xylose and glyoxylic acid were used as raw materials to synthesize diglyoxylic acid xylose (DGAX) by condensation reaction under concentrated sulfuric acid catalysis; the condensation reaction temperature was 90℃ and the reaction environment pressure was 40mbar.

[0023] (2) Add a large amount of methanol to directly esterify xylose diglyoxylate to generate xylose diglyoxylate DMGX with mixed configuration; (3) Using 2.9g of diglyoxylate xylose (DMGX) with a mixed configuration, 0.44g of ethylene glycol, and 2.90g of polytetramethylene ether glycol (PTMG) as raw materials, a multi-block copolymer PEDX-yPTMG (y represents the mass percentage of PTMG) was synthesized via a two-step transesterification-melt polycondensation method under catalytic conditions; this is the xylose-based thermoplastic polyester elastomer; the yield is above 90%, wherein the first step reaction temperature is 130℃ and the reaction time is 2h, and the second step reaction temperature is 145℃ and the reaction time is 3h; the catalyst is tetrabutyl titanate; the mass of the catalyst added is 0.05wt% of the diglyoxylate xylose in the raw materials. The reaction formula is as follows. Figure 1 As shown.

[0024] Example 5 A method for preparing a xylose-based thermoplastic polyester elastomer, comprising the following steps: (1) D-xylose and glyoxylic acid were used as raw materials to synthesize diglyoxylic acid xylose (DGAX) by condensation reaction under concentrated sulfuric acid catalysis; the condensation reaction temperature was 90℃ and the reaction environment pressure was 40mbar.

[0025] (2) Add a large amount of methanol to directly esterify xylose diglyoxylate to generate xylose diglyoxylate DMGX with mixed configuration; (3) Using 2.9g of diglyoxylate xylose (DMGX) with a mixed configuration, 0.38g of ethylene glycol, and 3.89g of polytetramethylene ether glycol (PTMG) as raw materials, a multi-block copolymer PEDX-yPTMG (y represents the mass percentage of PTMG) was synthesized via a two-step transesterification-melt polycondensation method under catalytic conditions; this is the xylose-based thermoplastic polyester elastomer; the yield is above 90%, wherein the first step reaction temperature is 130℃ and the reaction time is 2h, and the second step reaction temperature is 145℃ and the reaction time is 3h; the catalyst is tetrabutyl titanate; the mass of the catalyst added is 0.05wt% of the diglyoxylate xylose in the raw materials. The reaction formula is as follows. Figure 1 As shown.

[0026] The technical solutions provided by the present invention have been described in detail above. For those skilled in the art, there will be changes in specific implementation methods and application scope based on the ideas of the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a xylose-based thermoplastic polyester elastomer, characterized in that the steps include... include: (1) Using D-xylose and glyoxylic acid as raw materials, xylose diglyoxylate was synthesized by condensation reaction under concentrated sulfuric acid catalysis. (2) Add a large amount of methanol to directly esterify xylose diglyoxylate to generate xylose diglyoxylate with mixed configuration; (3) Using the diglyoxylate xylose and diol of the mixed configuration as raw materials, PEDX homopolymer is synthesized by a two-step method of transesterification-melt polycondensation under catalytic conditions, which is the xylose-based thermoplastic polyester elastomer.

2. The method for preparing a xylose-based thermoplastic polyester elastomer according to claim 1, characterized in that, In step (3), polytetramethylene ether glycol of different mass fractions is added to the raw materials, and multi-block copolymers are synthesized by a two-step method of transesterification-melt polycondensation under the conditions of tetrabutyl titanate catalyst.

3. The method for preparing a xylose-based thermoplastic polyester elastomer according to claim 1, characterized in that, The mixed-configuration xylose diglycidylate was separated into two different configurations by column chromatography. The mixed-configuration xylose diglycidylate in step (3) was then replaced with the two different configurations of xylose diglycidylate as raw materials, and homopolymers were synthesized by a two-step transesterification-melt polycondensation method under tetrabutyl titanate catalyst conditions.

4. A method for preparing a xylose-based thermoplastic polyester elastomer according to any one of claims 1 to 3, characterized in that, In step (1), the mass ratio of D-xylose, glyoxylic acid and concentrated sulfuric acid is D-xylose:glyoxylic acid:concentrated sulfuric acid = 20:50:3; the condensation reaction temperature is 90±5℃, and the reaction environment pressure is 30~50mbar.

5. A method for preparing a xylose-based thermoplastic polyester elastomer according to any one of claims 1 to 3, characterized in that, In step (3), the diol is ethylene glycol.

6. The method for preparing a xylose-based thermoplastic polyester elastomer according to claim 5, characterized in that, In step (3), the mass ratio of xylose diglycidyl ester to ethylene glycol is xylose diglycidyl ester to ethylene glycol = 2.8-3: 0.38-0.

55.

7. The method for preparing a xylose-based thermoplastic polyester elastomer according to claim 2, characterized in that, In step (3), the mass percentage of polytetramethylene ether glycol in the raw materials is 0.01% to 99%.

8. The method for preparing a xylose-based thermoplastic polyester elastomer according to claim 1, characterized in that, In step (3), the catalyst is tetrabutyl titanate, zinc acetate or antimony trioxide; the mass of the catalyst added is 0.05 wt% of the xylose diglyoxylate in the raw material.

9. The method for preparing a xylose-based thermoplastic polyester elastomer according to claim 1, characterized in that, In step (3), the reaction temperature of the first step is 130±5℃ and the reaction time is 2 to 3 hours, and the reaction temperature of the second step is 145±5℃ and the reaction time is 3 to 4 hours.

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