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

Abstract

The invention discloses a polyester nucleating additive based on block polymer self-assembly, and a method and application thereof, and the method comprises the following steps: dissolving Tbcl3, 4-benzoylbenzoic acid (p-BBA), 2, 2-dipyridyl (Bpy) and a block copolymer (PS-b-PAA) in a combined solvent, stirring the mixture at a certain temperature, carrying out a self-assembly reaction, and carrying out vacuum drying to obtain the polyester nucleating additive based on block polymer self-assembly. Dilute ammonia water is dropwise added in the reaction process to adjust the PH value to 7-8, washing and high-speed centrifugation are carried out for multiple times, an obtained product is put into a vacuum drying oven to be dried, and the polyester nucleating additive is obtained. The polyester nucleating additive has good compatibility with a polyester matrix, can crystallize and nucleate, shows an excellent nucleating induction effect on the polyester resin matrix, and can control various properties, including mechanical strength, crystallization rate, photoluminescence property and the like, of the polyester composite material by regulating and controlling the doping concentration.

Description

Technical Field

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

[0002] Polyester refers to a polymer compound containing an ester functional group on the main chain of the molecule, mainly polyethylene terephthalate (PET), and also conventionally includes thermoplastic resins such as polybutylene terephthalate (PBT). In the early 1840s, 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 the United States in 1946, after continuous development and research, it took the lead in producing and preparing polyester fibers by the ester exchange method, and finally achieved industrialization. Subsequently, polyester fibers quickly occupied an important position in the textile industry with their excellent mechanical properties and chemical stability. In 1973, polyester ushered in a major breakthrough in the field of packaging. Nathaniel Wyeth of the United States invented polyester blow molding technology and designed polyester bottles. This technology provides an ideal solution for the packaging of carbonated beverages and mineral water. Polyester bottles have gradually replaced glass bottles and aluminum cans with their light weight, high strength and recyclability, becoming 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 major engineering plastics. It has excellent mechanical strength, thermal stability, molding performance and good optical transparency, so it 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 received widespread attention. The molecular structure of polyester is highly ordered and has strong crystallization ability, but due to the high rigidity of its molecular chain, the glass transition temperature is high, which in turn limits the movement of the molecular chain, making polyester a semi-crystalline material. In order to overcome the disadvantage of the slow crystallization speed of polyester, researchers have carried out a large number of modification studies and developed a variety of nucleating agents to promote its crystallization process. Existing nucleating agents mainly include inorganic nucleating agents, organic nucleating agents and polymer nucleating agents. Each type of nucleating agent has its unique advantages and limitations in application. Despite this, additives that combine crystallization induction with efficient luminescence in the same polymer material are still relatively scarce. Therefore, exploring the preparation method of hybrid luminescent materials that can simultaneously possess these two functions has important academic and practical significance for improving the performance of polyester and expanding its application areas. Summary of the invention

[0004] The purpose of the present invention is to provide a polyester nucleation additive based on block polymer self-assembly, a method and an application thereof, and a terbium ion-induced block copolymer is prepared by a self-assembly method to form uniform nanoaggregates. The terbium ion-induced block copolymer is doped in polyester as a nucleation additive to prepare a polyester hybrid luminescent material, which not only has a high luminous intensity, but also improves its mechanical properties and crystallization properties.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing a polyester nucleating additive based on block polymer self-assembly comprises the following steps:

[0007] Tbcl 3 , 4-benzoylbenzoic acid (p-BBA), 2,2-bipyridine (Bpy) and block copolymer (PS-b-PAA) are dissolved in a combined solvent, and the mixture is stirred at a certain temperature to carry out a self-assembly reaction. During the reaction, dilute ammonia water is added dropwise to adjust the pH value to 7-8. After multiple washings and high-speed centrifugation, the obtained product is placed in a vacuum drying oven and dried to obtain a polyester nucleating additive.

[0008] The preparation method, Tbcl 3 , 4-benzoylbenzoic acid (p-BBA), 2,2-bipyridine (Bpy) and block copolymer (PS-b-PAA) in a molar ratio of 1:3:1:1.

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

[0010] The preparation method comprises stirring the mixture at 60-80° C. for 6-8 hours.

[0011] The preparation method, the PS-b-PAA segment length range is: the segment length of polystyrene (PS) is 21-50, and the segment length of polyacrylic acid (PAA) is 5-20.

[0012] The preparation method comprises acetylacetone (ACAC), sodium malonate (SM), o-phenanthroline (Phen), α-methylacrylic 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 self-assembly of block polymers is applied to melt-blend the polyester nucleating additive and polyester powder to improve the crystallization performance and mechanical properties of the polyester material.

[0015] In the application, the polyester nucleating additive powder and the PET powder are placed in a vacuum drying oven for drying to eliminate the solvent and prevent bubbles from appearing during the injection molding process.

[0016] The application, polyester nucleating additive powder and polyester raw material, the temperature of the vacuum drying box is step-by-step heating, the temperature program is: 25-80°C for 3-10 hours, 90-150°C for 10-30 hours.

[0017] In the application, polyester nucleating additive powder and polyester powder are melt-blended, put into a twin-screw micro-mixing extruder for melt extrusion according to a certain ratio, and processed and formed by an injection molding machine to prepare a polyester hybrid luminescent material.

[0018] In the application, the polyester nucleating additive powder accounts for 0.3wt%-2wt% of the polyester resin monomer.

[0019] In the application, the extrusion process is that the temperature gradient of the feeding barrel is 255-270°C / 270-280°C / 280-290°C, the rotation speed is 20-550rpm, and inert gas such as nitrogen, argon, helium, etc. is introduced into the extrusion process as needed to prevent oxidation.

[0020] In the application, the injection molding process is as follows: the gun tip temperature is 245-290°C, the mold temperature is 30-120°C, 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.

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

[0022] By overall designing the hybrid luminescent material, a new type of nano-nucleation-induced and highly efficient luminescent material is constructed. 3+ )-induced diblock polystyrene-polyacrylic acid aggregates (TIPAs), and used them as nano-additives to melt blend with polyester, successfully preparing a hybrid luminescent composite polyester material. In this process, the carbonyl group in the polyester molecular structure becomes a ligand of the terbium complex for coordination. The rare earth ion (Tb 3+)-induced diblock copolymer polystyrene-polyacrylic acid (PS-PAA) forms nanospheres, one end of PS is hydrophobic and the other end of PAA is hydrophilic. They can be evenly distributed in the solution by self-assembly. This special block structure effectively prevents the agglomeration between different media, and has good compatibility and light transmittance after mixing with polyester, which improves its dispersibility in the polyester matrix. The inorganic nanoparticles are modified with organic high molecular polymers to form organic-inorganic nucleating additives, which improves the interfacial compatibility of the polyester matrix and the crystallization and mechanical properties of the polyester material. Therefore, hybrid nanoluminescent materials have broad application prospects as new polyester additives and provide new ideas for the development of new functional polymer composites. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the process of the present invention;

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

[0025] Figure 3 Tb 3+ Complex and Tb 3+ - Excitation and emission spectra of nanoaggregates;

[0026] Figure 4 Doped with Tb 3+ -Infrared spectra of nanoaggregate polyester hybrid luminescent materials;

[0027] Figure 5 The DSC cooling and heating curves of polyester hybrid luminescent materials doped with different concentrations are shown respectively;

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

[0029] The present invention is described in detail below in conjunction with specific embodiments.

[0030] Embodiment 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, followed by the addition of 3.12 g of styrene monomer and the flask was sealed with a rubber stopper. The mixture was nitrogen-filled for 40-60 minutes to exclude oxygen, and then 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 drying oven at 80-100°C for 6-9 hours to obtain a polystyrene (PS) solid.

[0032] (2) Synthesis of block copolymer (polystyrene-b-polyacrylic acid) (PS-b-PAA): First, in a 25 ml round-bottom flask, add 1.0 g of the prepared PS and 0.054 g of AIBN, add 7 mL of 1,4-dioxane, and then add 0.33 g of acrylic acid. Quickly seal the flask with a rubber stopper. Then pass nitrogen to isolate oxygen. Then heat and stir in an oil bath at 60-90°C for 7-10 hours. After washing the product with petroleum ether, precipitate overnight and dry it in a vacuum drying oven at 60-90°C for 8-10 hours. Finally, a PS-PAA diblock copolymer is obtained.

[0033] Embodiment 2:

[0034] (1)Tb 3+ Preparation of complexes: First, prepare TbCl 3 6H 2 O, 4-benzoylbenzoic acid (BBA) and 0.1 mol / L ethanol solution of 2,2-bipyridine (Bpy). The three solutions were mixed in a molar ratio of 1:3:1 and stirred at room temperature for 1 hour to ensure sufficient mixing. Subsequently, dilute ammonia water was gradually added to adjust the pH value of the solution to 7-8, and stirring was continued at room temperature for 4 hours. During this process, the solution gradually became turbid. After that, it was washed three times with ethanol and the solid product was separated by centrifugation, and finally placed in a vacuum drying oven at 80°C for 8 hours to obtain Tb 3+ Complex.

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

[0036] Figure 2 Transmission electron microscopy (TEM) images of Tb3+ nanoaggregates are shown. Figures (a) and (b) show the transmission electron microscopy images of TIPA1 and TIPA2, respectively, while Figures (c) and (d) show the particle size distribution of the two samples. As can be seen from the figure, the particle size of TIPA1 is mainly concentrated between 200nm and 400nm, while the particle size of TIPA2 is distributed between 450nm and 550nm. From the TEM images, it can be seen that TIPA1 and TIPA2 have small, regular and uniform spherical structures. Their dark core and light crown may be due to the stable structure formed by the hydrophobic PS segment and the hydrophilic PAA segment during the self-assembly process due to the different solubility. In addition, the coordination between the terbium ions and the carboxyl oxygen atoms in the PAA segment also increases the stability of the 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 a spherical structure, thereby reducing energy loss.

[0037] Figure 3 Tb 3+ Complex and Tb 3+ -excitation (a) and emission spectra (b) of nanoaggregates. As can be seen from the figure, Tb 3+ The excitation peak of the complex is at 350nm, while Tb 3+ -The excitation peak of the nanoaggregates is red-shifted to 370nm. This significant red shift is mainly attributed to the introduction of PS-PAA, which changes the local environment of the luminescence center. The carboxyl groups in PS-PAA and Tb 3 + ions form coordination effects, weakening the ligand field strength and reducing the energy of electronic transition. In addition, the molecular stacking effect caused by PS-PAA enhances the π-π interaction between molecules, further reducing the energy gap of electronic transition, thereby promoting the occurrence of red shift.

[0038] Embodiment 3:

[0039] The TIPAs powder and PET powder prepared in Example 2 were placed in a vacuum drying oven for drying, respectively, and the drying procedure was: 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 mass fractions of 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, and 2%, and placed in a twin-screw micro-mixing extruder for melt blending. The extrusion process was: the feed barrel temperature gradient was 255-270°C / 270-280°C / 280-290°C, the rotation speed was 20-550rpm, and inert gas was introduced into the extrusion process as needed to prevent oxidation. The pressure and time of the injection molding machine were adjusted. The injection molding process was as follows: the temperature of the gun tip was 245-290°C, the temperature of the mold was 30-120°C, the injection pressure, holding pressure and back pressure were 0-10Mpa, the injection time was 1-55s, the holding time was 1-38s, and the back pressure time was 1-30s. Standard samples were made, and a total of seven groups of samples of polyester hybrid luminescent materials 0.3wt%-2wt% and pure PET were prepared for testing of mechanical properties, crystallization properties, fluorescence properties, etc.

[0040] Figure 4 Tb-doped 3+ -Infrared spectrum of nanoaggregate polyester hybrid luminescent material. In pure polyester, the carbonyl (C=O) stretching vibration peak is located at around 1720cm-1, which is a typical characteristic peak of polyester. Its position has shifted in the polyester hybrid material, which indicates that the components in TIPAs (such as the carboxyl group in PAA) interact with the C=O group of the polyester, resulting in a change in the electronic environment of the carbonyl group. The CH out-of-plane bending vibration peak of the benzene ring in the polyester is located at 722cm-1. The COC stretching vibration peaks of pure polyester at 1240cm-1 and 1100cm-1 are its characteristic peaks, characterizing the ester bond structure of the polyester. The COC peak in the polyester hybrid material has changed in its displacement and intensity, which may suggest that Tb 3+ -The nanoaggregates interacted with the ester group of polyester, causing the electron cloud density of the COC bond of polyester to change. The changes in the above infrared characteristic peaks together prove that a reaction occurred between TIPAs and polyester.

[0041] Figure 5 Table 1 is the DSC cooling and heating curves of polyester hybrid luminescent materials doped with different concentrations. 3+ - Crystallization data of modified luminescent polyester of nanoaggregates, it can be seen that the addition of Tb 3+ -The thermal crystallization peak Tc value of the polyester composite material with nano-aggregates is higher than that of pure polyester, and the crystallization peak is stronger. 3+-The crystallization temperature and crystallinity of the polyester material of nanoaggregates are higher than those of pure polyester. The crystallization temperature first increases and then decreases with the increase of crystallinity, until the crystallization temperature and crystallinity reach the highest when the doping content is 1.2wt%. Generally, the rightward shift of the crystallization peak means the increase of crystallization temperature. This phenomenon is due to the heterogeneous nucleation effect caused by doping. The heterogeneous nucleating agent TIPAs can act as a crystallization core to promote the crystallization process of the polyester material, so that crystallization occurs at a higher temperature.

[0042] Figure 6 The micro-spectral analysis of hybrid luminescent polyester materials doped with different contents of TIPAs shows that pure PET has no emission peak in the range of 450-650nm, while the polyester hybrid luminescent material shows obvious Tb at 548nm. 3+ As the TIPAs doping concentration increases to 1.2wt%, the fluorescence intensity of the material gradually increases, and further addition leads to a decrease in fluorescence intensity. This phenomenon is mainly because at a lower doping concentration, Tb 3+ As the luminescence center, ions can effectively absorb excitation light and emit characteristic fluorescence, while the large molecular distance avoids significant interactions, thereby maintaining a high fluorescence intensity. The decrease in fluorescence intensity can be attributed to the "concentration quenching effect", which increases non-radiative transitions due to energy transfer caused by enhanced intermolecular interactions, thereby weakening fluorescence emission.

[0043] Table 1: Tb doping 3+ - Crystallization data of modified luminescent polyesters based on nanoaggregates

[0044]

[0045] Table 2: Tb doping 3+ -Mechanical properties of luminescent polyester modified by nanoaggregates

[0046]

[0047] TIPAs-doped polyester composites exhibited the best mechanical properties at a concentration of 1.2 wt%, which was mainly attributed to the rare earth metal ions (Tb 3+ ) with 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+By coordinating with BBA and Bpy to form a highly stable complex structure, the rigidity and three-dimensional stability of this structure provide a solid foundation for enhancing the mechanical properties of composite materials. In the polyester matrix, the functional groups rich in the surface of TIPAs (such as carboxyl, pyridine ring, etc.) 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 can effectively transfer stress under external loads, thereby improving the tensile strength of the material. In addition, TIPAs further promote the formation of crystalline regions by limiting the freedom of movement of polyester molecular chains, thereby improving the rigidity and mechanical stability of the matrix.

[0048] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for preparing a polyester nucleating additive based on block polymer self-assembly, characterized in that: The following steps are involved: Tbcl3, 4-benzoylbenzoic acid (p-BBA), 2,2-bipyridine (Bpy) and block copolymer (PS-b-PAA) are dissolved in a combined solvent, and the mixture is stirred at a certain temperature to carry out a self-assembly reaction. During the reaction, dilute ammonia water is added dropwise to adjust the pH value to 7-8. After multiple washings and high-speed centrifugation, the obtained product is placed in a vacuum drying oven for drying to obtain a polyester nucleating additive.

2. The preparation method according to claim 1, characterized in that: 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.

3. The preparation method according to claim 1, characterized in that: Dichloromethane and ethanol were 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 was stirred at 60-80°C for 6-8 hours.

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

6. The preparation method according to claim 1, characterized in that: The organic ligands include acetylacetone (ACAC), sodium malonate (SM), o-phenanthroline (Phen), α-methylacrylic acid (MAA), 4-benzoylbenzoic acid (BBA), and 2,2-bipyridine (Bpy).

7. A polyester nucleating additive based on block polymer self-assembly prepared according to the preparation method according to any one of claims 1 to 6.

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

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

10. The use according to claim 9, characterized in that: The extrusion process is as follows: the temperature gradient of the feed barrel is 255-270℃ / 270-280℃ / 280-290℃, the rotation speed is 20-550rpm, and inert gas such as nitrogen, argon, helium, etc. is introduced into the extrusion process as needed to prevent oxidation; the injection molding process is as follows: the gun tip 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.

Images