Polyester nucleating additive based on block polymer self-assembly, method and use

Abstract

The application discloses a polyester nucleating additive based on block polymer self-assembly and a method and application thereof, and comprises the following steps: dissolving Tbcl3, 4-benzoylbenzoic acid (p-BBA), 2,2-bipyridine (Bpy) and a block copolymer (PS-b-PAA) in a combined solvent, stirring the mixture at a certain temperature, performing a self-assembly reaction, adding diluted ammonia water dropwise to adjust the pH value to 7-8 during the reaction, performing multiple washing and high-speed centrifugation, placing the obtained product into a vacuum drying box for drying, and obtaining the polyester nucleating additive. The polyester nucleating additive has good compatibility with a polyester matrix, can be crystallized to form a nucleus, presents excellent nucleation induction effect on the polyester resin matrix, and can control various performances of the polyester composite material, including mechanical strength, crystallization rate, photoluminescence performance and the like, by adjusting and controlling a doping concentration.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polyester modification, in particular to a polyester nucleating additive based on block polymer self-assembly and a method and application thereof. BACKGROUND

[0002] Polyester refers to a high molecular compound containing ester functional groups in the main chain of the molecule, mainly refers to polyethylene terephthalate (PET), and also includes polybutylene terephthalate (PBT) and other thermoplastic resins. In the early 1940s, British researchers Whinfield and Dickson first synthesized polyethylene terephthalate (PET) using dimethyl terephthalate and ethylene glycol as raw materials, and applied for the first patent in the history of PET development. After the patent was purchased by DuPont in 1946, through continuous development and research, polyester fibers were first produced by ester exchange method, and finally industrialized. Subsequently, polyester fibers rapidly occupied an important position in the textile industry due to their excellent mechanical properties and chemical stability. In 1973, polyester made a major breakthrough in the packaging field, and Nathaniel Wyeth of the United States invented polyester blow molding technology and designed polyester bottles, which provided an ideal solution for the packaging of carbonated beverages and mineral water. Polyester bottles gradually replaced glass bottles and aluminum cans due to their light weight, high strength and recyclability, and became the mainstream material in the global packaging industry.

[0003] As an important thermoplastic polymer, polyester is widely used in industry, agriculture, national defense and daily consumer goods, and is listed as one of the five engineering plastics. It has excellent mechanical strength, thermal stability, molding performance and good optical transparency, and is widely used in various fields. In recent years, with the gradual deepening of research on polyester and its modification technology, the modification of polyester has attracted widespread attention. The molecular structure of polyester is highly ordered, and has strong crystallization ability. However, due to the high rigidity of the molecular chain, the glass transition temperature is high, which limits the movement of the molecular chain, making polyester a semi-crystalline material. In order to overcome the slow crystallization speed of polyester, researchers have carried out a lot of modification research, and have developed various nucleating agents to promote the crystallization process. Existing nucleating agents mainly include inorganic nucleating agents, organic nucleating agents and high molecular nucleating agents, each type of nucleating agent has its unique advantages and limitations in application. However, at present, additives that can realize the combination of crystallization induction and high-efficiency luminescence function in the same high polymer material are still rare. Therefore, exploring the preparation method of hybrid luminescent materials that can simultaneously possess both functions has important academic and practical significance for improving the performance of polyester and expanding its application field. SUMMARY

[0004] The application aims to provide a polyester nucleating additive based on block polymer self-assembly, a method and an application, and a terbium ion induced block copolymer is prepared into uniform nanoclusters by a self-assembly method.

[0005] The technical scheme of the application is as follows:

[0006] A preparation method of a polyester nucleating additive based on block polymer self-assembly, comprising the following steps:

[0007] Tbcl3, 4-benzoylbenzoic acid (p-BBA), 2,2-bipyridine (Bpy) and block copolymer (PS-b-PAA) are dissolved in a combined solvent, the mixture is stirred at a certain temperature to perform a self-assembly reaction, dilute ammonia water is added dropwise to adjust the pH value to 7-8 during the reaction, the obtained product is dried in a vacuum drying box after multiple washing and high-speed centrifugation, and a polyester nucleating additive is obtained.

[0008] In the preparation method, the molar ratio of Tbcl3, 4-benzoylbenzoic acid (p-BBA), 2,2-bipyridine (Bpy) and block copolymer (PS-b-PAA) is 1:3:1:1.

[0009] In the preparation method, dichloromethane and ethanol are mixed in a ratio of 1:2 to obtain the combined solvent.

[0010] In the preparation method, the mixture is stirred at 60-80 DEG C for 6-8 hours.

[0011] In the preparation method, the length of the PS-b-PAA block ranges from 21 to 50 for polystyrene (PS) and from 5 to 20 for polyacrylic acid (PAA).

[0012] In the preparation method, the organic ligand includes acetylacetone (ACAC), sodium malonate (SM), phenanthroline (Phen), alpha-methyl acrylic acid (MAA), 4-benzoylbenzoic acid (BBA) and 2,2-bipyridine (Bpy).

[0013] The polyester nucleating additive based on block polymer self-assembly is prepared according to the above preparation method.

[0014] The polyester nucleating additive based on block polymer self-assembly is applied by melt blending the polyester nucleating additive and polyester powder to improve the crystallization performance and mechanical properties of the polyester material.

[0015] The application is characterized in that the polyester nucleating additive powder and the PET powder are respectively placed in a vacuum drying box for drying treatment to eliminate solvent and prevent bubbles from occurring in the injection molding process.

[0016] The application is characterized in that the polyester nucleating additive powder and the polyester raw material are subjected to step-by-step temperature rising in the vacuum drying box, and the temperature program is 25-80 DEG C for 3-10 hours and 90-150 DEG C for 10-30 hours.

[0017] The application is characterized in that the polyester nucleating additive powder and the polyester powder are subjected to melt blending according to a certain proportion, melt extrusion is performed in a double-screw micro mixing extruder, and injection molding is performed to prepare the polyester hybrid luminescent material.

[0018] The application is characterized in that the polyester nucleating additive powder accounts for 0.3wt%-2wt% of the polyester resin monomer.

[0019] The application is characterized in that the feeding cylinder temperature gradient of the extrusion process is 255-270 DEG C / 270-280 DEG C / 280-290 DEG C, the rotation speed is 20-550 rpm, inert gas such as nitrogen, argon and helium is introduced according to needs in the extrusion process to prevent oxidation.

[0020] The application is characterized in that the injection molding process is characterized in that the gun head temperature is 245-290 DEG C, the mold temperature is 30-120 DEG C, the injection pressure, the holding pressure and the back pressure are 0-10 Mpa, the injection time is 1-55 s, the holding time is 1-38 s, and the back pressure time is 1-30 s.

[0021] Compared with the prior art, the application has the following advantages:

[0022] The hybrid luminescent material is designed as a whole to construct a novel nano nucleation induction and high-efficiency luminescent material. 3+ ) induced diblock polystyrene-polyacrylic acid aggregates (TIPAs) are used as nano additives to melt blend with the polyester, and the hybrid luminescent composite polyester material is successfully prepared. 3+)induced diblock copolymer polystyrene-polyacrylic acid (PS-PAA) nanosphere, PS end has hydrophobicity, PAA end has hydrophilicity, through self-assembly can be uniformly distributed in solution, this special block structure effectively prevents the agglomeration between different media, and has good compatibility and light transmittance after mixing with polyester, improves its dispersibility in polyester matrix. The inorganic nanoparticles are modified by organic polymer to form organic-inorganic nucleating additive, which improves the interface compatibility of polyester matrix and improves the crystallization performance and mechanical properties of polyester material. Therefore, the hybrid nanometer luminescent material has wide application prospect as a new type of polyester additive, and provides a new idea for the development of new functional polymer composite materials. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the flowchart of the present application;

[0024] Figure 2 is Tb 3+ - TEM images and particle size distribution of nanoclusters (TIPA1 and TIPA2);

[0025] Figure 3 is Tb 3+ complex and Tb 3+ - excitation and emission spectra of nanoclusters;

[0026] Figure 4 doped with Tb 3+ - infrared spectrum of nanocluster polyester hybrid luminescent material;

[0027] Figure 5 is respectively the DSC cooling and heating curve of polyester hybrid luminescent material doped with different concentrations;

[0028] Figure 6 is the microscopic micro-area spectral analysis of hybrid luminescent polyester material doped with different contents of TIPAs; DETAILED DESCRIPTION

[0029] The present application will be described in detail below in combination with specific examples.

[0030] Example 1:

[0031] (1) Synthesis of Polystyrene (PS): First, 0.263 g of RAFT agent and 0.054 g of AIBN were dissolved in 7 mL of 1,4-dioxane, then 3.12 g of styrene monomer was added, and the flask was sealed with a rubber plug. After the mixture was treated with nitrogen for 40-60 minutes to exclude oxygen, it was heated and stirred in an oil bath at 60-80°C for 7-10 hours. After the reaction, the product was washed with methanol, precipitated overnight, and dried in a vacuum oven at 80-100°C for 6-9 hours to obtain polystyrene (PS) solid.

[0032] (2) Synthesis of Block Copolymer (Polystyrene-b-Polyacrylic acid) (PS-b-PAA): First, 1.0 g of prepared PS and 0.054 g of AIBN were added to a 25 ml round-bottom flask, and 7 mL of 1,4-dioxane was added, followed by the addition of 0.33 g of acrylic acid. The flask was quickly sealed with a rubber plug. Then nitrogen was bubbled through to exclude oxygen. Then the mixture was heated and stirred in an oil bath at 60-90°C for 7-10 hours. The product was washed with petroleum ether, precipitated overnight, and dried in a vacuum oven at 60-90°C for 8-10 hours. Finally, the PS-PAA diblock copolymer was obtained.

[0033] Example 2:

[0034] (1) Tb 3+ Preparation of the complex: First, 0.1 mol / L ethanol solutions of TbCl3·6H2O, 4-benzoylbenzoic acid (BBA), and 2,2-bipyridine (Bpy) were prepared, respectively. The three solutions were mixed in a molar ratio of 1:3:1 and stirred at room temperature for 1 hour to ensure thorough mixing. Then, the pH value of the solution was adjusted to 7-8 by gradually adding dilute ammonia water, and stirring was continued at room temperature for 4 hours. During this process, the solution gradually became turbid. After that, ethanol was used for washing three times and the solid product was separated by centrifugation, and finally dried in a vacuum oven at 80°C for 8 hours to obtain Tb 3+ complex.

[0035] (2) Tb 3+ Nanocluster powder preparation (TIPAs): Dichloromethane and ethanol were mixed in a ratio of 1:2 to obtain a mixed solvent, and TbCl3·6H2O, 4-benzoylbenzoic acid (p-BBA), 2,2-bipyridine (Bpy), and block copolymer (PS-b-PAA) were dissolved in the above combined solvent in a molar ratio of 1:3:1:1. The mixture was stirred at a temperature of 60-80°C for 6 hours to carry out self-assembly reaction, and dilute ammonia water was added dropwise to adjust the pH value to about 7-8 during the reaction, resulting in turbidity of the solution. After multiple washing and high-speed centrifugation, the obtained product was dried in a vacuum oven at 70°C to obtain TIPAs.

[0036] Figure 2 Transmission electron microscopy (TEM) images of Tb3+nanoclusters are shown. Figures (a) and (b) show the TEM images of TIPA1 and TIPA2, respectively, while figures (c) and (d) show the particle size distribution of the two samples. It can be seen from the figures that the particle size of TIPA1 is mainly concentrated between 200 nm and 400 nm, while the particle size distribution of TIPA2 is between 450 nm and 550 nm. From the TEM images, it can be seen that TIPA1 and TIPA2 have small and regular and uniform spherical structures. Their dark cores and light crowns may be due to the stable structure formed by the hydrophobic PS segments and the hydrophilic PAA segments during the self-assembly process due to the difference in solubility. In addition, the coordination between terbium ions and carboxyl oxygen atoms in the PAA segment also increases the stability of self-assembly. In order to maintain the stability of the nanostructure and prevent its disintegration, the surface energy needs to be reduced, which is conducive to the formation of spherical structure, thereby reducing the energy loss.

[0037] Figure 3 Tb 3+ complex and Tb 3+ - The excitation (a) and emission spectra (b) of the nanoclusters. It can be seen from the figures that the excitation peak of the Tb 3+ complex is located at 350 nm, while the excitation peak of the Tb 3+ - nanoclusters is red-shifted to 370 nm. This significant red shift is mainly due to the introduction of PS-PAA, which changes the local environment of the luminescent center. The carboxyl groups in PS-PAA form coordination with Tb 3 ions, weakening the ligand field strength and reducing the energy of electronic transition. In addition, the molecular packing effect induced by PS-PAA enhances the intermolecular π-π interaction, further reducing the energy gap of electronic transition, thus promoting the occurrence of red shift phenomenon.

[0038] Example 3:

[0039] The TIPAs powder and PET powder prepared in Example 2 were dried in a vacuum drying oven, and the drying procedure was as follows: 25-80°C for 3-10 hours, 90-150°C for 10-30 hours. After the twin-screw micro mixing extruder was preheated for two hours, the dried TIPAs powder and polyester powder were uniformly mixed according to the mass fraction of 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, and 2%, and then were put into the twin-screw micro mixing extruder for melt blending. The extrusion process was as follows: the temperature gradient of the feeding cylinder was 255-270°C / 270-280°C / 280-290°C, the rotating speed was 20-550 rpm, and inert gas was introduced during the extrusion process as needed to prevent oxidation. The pressure and time of the injection molding machine were adjusted, and the injection molding process was as follows: the gun head temperature was 245-290°C, the mold temperature was 30-120°C, the injection pressure, holding pressure, and back pressure were 0-10 MPa, the injection time was 1-55 s, the holding time was 1-38 s, and the back pressure time was 1-30 s. Standard samples were prepared, and seven groups of polyester hybrid luminescent materials with 0.3wt%-2wt% and pure PET were prepared for testing the mechanical properties, crystallization properties, and fluorescence properties.

[0040] Figure 4 Tb-doped 3+ - Infrared spectrum of the nanocluster polyester hybrid luminescent material. In pure polyester, the C=O stretching vibration peak is located at about 1720 cm-1, which is a typical characteristic peak of polyester. In the polyester hybrid material, the position of the peak is shifted, which indicates that the components in TIPAs (such as the carboxyl group in PAA) interact with the C=O group of polyester, resulting in a change in the electronic environment of the carbonyl group. The C-H out-of-plane bending vibration peak of the benzene ring in polyester is located at 722 cm-1. The C-O-C stretching vibration peaks of pure polyester at 1240 cm-1 and 1100 cm-1 are characteristic peaks representing the ester bond structure of polyester. In the polyester hybrid material, the C-O-C peak is shifted and the intensity is changed, which may indicate that the Tb 3+ - The nanoclusters interact with the ester group of polyester, changing the electron cloud density of the C-O-C bond of polyester. The changes in the above infrared characteristic peaks collectively prove that a reaction occurs between TIPAs and polyester.

[0041] Figure 5 The DSC cooling and heating curves of the polyester hybrid luminescent materials doped with different concentrations of Tb 3+ - The crystallization data of the modified luminescent polyester of the nanocluster. It can be seen that the addition of Tb 3+ - The thermal crystallization peak Tc value of the polyester composite of the nanocluster is higher than that of pure polyester, and the crystallization peak is strong. Under the same conditions, the Tb 3+- The crystallization temperature and crystallinity of the polyester material of the nanoclusters are higher than that of the pure polyester. The crystallization temperature increases first and then decreases with the increase of the crystallinity, and reaches the highest value when the doping content is 1.2wt%. Generally, the right shift of the crystallization peak means the increase of the crystallization temperature, and this phenomenon is due to the heterogeneous nucleation effect caused by the doping. The heterogeneous nucleating agent TIPAs can act as the crystallization core to promote the crystallization process of the polyester material, so that the crystallization occurs at a higher temperature.

[0042] Figure 6 For the micro-area spectral analysis of the hybrid luminescent polyester material doped with different contents of TIPAs, it can be seen that the pure PET has no emission peak in the range of 450-650 nm, while the hybrid luminescent polyester material exhibits a clear Tb 3+ emission peak at 548 nm. With the increase of the doping concentration of TIPAs to 1.2wt%, the fluorescence intensity of the material gradually increases, and further addition leads to the decrease of the fluorescence intensity. This phenomenon is mainly because at a lower doping concentration, Tb 3+ ions act as luminescent centers, can effectively absorb excitation light and emit characteristic fluorescence, and the intermolecular distance is large, which avoids significant interaction and maintains a high fluorescence intensity. The decrease of the fluorescence intensity can be attributed to the "concentration quenching effect", which is caused by the energy transfer due to the increase of the intermolecular interaction, which increases the non-radiative transition, thereby weakening the fluorescence emission.

[0043] Table 1: Doping Tb 3+ - Crystallization data of the modified luminescent polyester of the nanoclusters

[0044]

[0045] Table 2: Doping Tb 3+ - Mechanical properties of the modified luminescent polyester of the nanoclusters

[0046]

[0047] The polyester composite material doped with TIPAs exhibits the best mechanical properties at a concentration of 1.2wt%, which is mainly due to the synergistic coordination between the rare earth metal ions (Tb 3+ ) in TIPAs and the organic ligand and the polyester matrix, and the good dispersibility and compatibility of TIPAs in the polyester matrix. In the structure of TIPAs, Tb 3+The coordination with BBA and Bpy forms a highly stable complex structure, and the rigidity and three-dimensional stability of this structure provide a solid foundation for enhancing the mechanical properties of the composite material. In the polyester matrix, the functional groups (such as carboxyl, pyridine ring, etc.) on the surface of TIPAs form secondary chemical bonds (such as coordination bonds and hydrogen bonds) with the carbonyl (C=O) and ester groups in the polyester molecular chain through coordination. This multiple coordination interaction not only enhances the interfacial bonding force between TIPAs and the polyester matrix, but also effectively transmits stress under external load, thereby improving the tensile strength of the material. In addition, TIPAs further promote the formation of crystalline regions by limiting the freedom of motion of the polyester molecular chain, thereby improving the rigidity and mechanical stability of the matrix

[0048] It should be understood that, for those of ordinary skill in the art, improvements or changes can be made according to the above description, and all such improvements and changes shall fall within the protection scope of the appended claims of the present application.

Claims

1. A process for the preparation of a polyester nucleating additive based on the self-assembly of block polymers, characterized in that, The method comprises the following steps: Tbcl3, 4-benzoyl benzoic acid (p-BBA), 2,2-bipyridine (Bpy) and block copolymer PS-b-PAA are dissolved in a combined solvent, the mixture is stirred at a certain temperature, a self-assembly reaction is carried out, and dilute ammonia water is added dropwise to adjust the pH value to 7-8 during the reaction; the obtained product is dried in a vacuum drying box after multiple washing and high-speed centrifugation, and a polyester nucleating additive is obtained.

2. The production method according to claim 1, characterized by, The molar ratio of Tbcl3, 4-benzoyl benzoic acid (p-BBA), 2,2-bipyridine (Bpy) and block copolymer PS-b-PAA is 1:3:1:

1.

3. The production method according to claim 1, characterized by, Dichloromethane and ethanol are mixed in a ratio of 1:2 to obtain a combined solvent.

4. The preparation method according to claim 1, characterized in that, The mixture is stirred at 60-80°C for 6-8 hours.

5. The preparation method according to claim 1, characterized in that, The length of the PS-b-PAA segment ranges from 21 to 50 for polystyrene (PS) and from 5 to 20 for polyacrylic acid (PAA).

6. The polyester nucleating additive based on block polymer self-assembly prepared by the method according to any one of claims 1-5.

7. The polyester nucleating additive based on block polymer self-assembly according to claim 6, wherein the polyester nucleating additive and polyester powder are melt blended to improve the crystallization performance and mechanical properties of the polyester material.

8. Use according to claim 7, characterized in that, The polyester nucleating additive powder and polyester powder are melt blended in a certain proportion, put into a double-screw micro mixing extruder for melt extrusion, and processed into a polyester hybrid luminescent material by an injection molding machine; the polyester nucleating additive powder accounts for 0.3wt%-2wt% of the polyester resin monomer.

9. Use according to claim 8, characterized in that, The extrusion process is that the temperature gradient of the feeding cylinder is 255-270℃ / 270-280℃ / 280-290℃, the rotation speed is 20-550rpm, inert gas is introduced during the extrusion process as needed to prevent oxidation; the injection molding process is that the gun head temperature is 245-290℃, the mold temperature is 30-120℃, the injection pressure, holding pressure and back pressure are 0-10Mpa, the injection time is 1-55s, the holding time is 1-38s, and the back pressure time is 1-30s.

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