Polyolefin modified material with fluorescence characteristic and preparation method thereof

Abstract

The invention belongs to the technical field of new materials, and particularly relates to a polyolefin modified material and a method. The preparation method comprises the following steps: adding organic peroxide into polyolefin, and directly grafting peroxide free radicals generated by high-temperature decomposition of the organic peroxide to a polyolefin main chain in a melt blending process by adopting a melt blending technology under the condition of not adding any other substances with light-emitting characteristics; aggregation-induced emission is caused by formation of expanded n-pi * and pi-pi * space conjugation, and a polyolefin modified material which has relatively high fluorescence performance and can be processed by using a conventional traditional melting processing method is obtained; the mass ratio of the polyolefin to the organic peroxide is 100: (1-10); the polyolefin modified material obtained by the invention not only has good fluorescence characteristics, but also has good melt processability. The method is simple and convenient, low in cost and easy for large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of new materials, and specifically relates to a polyolefin modified material and method. Background Art

[0002] With the growing demand for flexible wearable devices, the development of flexible luminescent materials has become crucial. Polymer materials are known for their light weight, high flexibility and easy processability, which makes them show great potential in the future application and development of flexible luminescent materials. Among the many luminescent materials, conjugated polymers are ideal candidates for light-emitting devices due to their excellent optoelectronic properties, such as high charge carrier mobility and high photoluminescence quantum efficiency. Through solution processing techniques such as spin coating, casting and printing, conjugated polymers can be made into large-area products and widely used in flexible displays and organic photovoltaic devices to meet the market demand for lightweight, portable and energy-efficient electronic devices. However, the high cost, complex synthesis and processing of conjugated polymers, and potential environmental impact during the production process are all major challenges currently faced. Therefore, in order to meet the growing demand for flexible wearable applications, it is urgent to develop technologies that are both easy to mass-produce to develop cost-effective luminescent materials with good mechanical properties and excellent processing properties.

[0003] Polyolefins are low-cost and have excellent chemical stability, mechanical properties, and processability, making them a widely used material in daily life. Generally, polyolefins are considered to be a typical general-purpose material and are not considered luminescent materials themselves. At present, the method for preparing polyolefin-related luminescent materials is usually to add substances with luminescent properties to polyolefins. For example, by physically mixing fluorescent substances into polyolefins through blending, luminescent materials based on polyolefins can be prepared. However, this method usually leads to uneven dispersion due to the poor compatibility of fluorescent substances with polyolefins, which affects the optical and mechanical properties of the final product. There are also studies on introducing luminescent substances such as polycyclic aromatic hydrocarbon compounds, quantum dots or rare earth complexes into polyolefins through reactive grafting, but this method involves complex chemical reactions, often requires expensive and environmentally unfriendly solvents, is complex to operate, and has high production costs.

[0004] Peroxides play an important role in the high-performance or functional modification of polyolefins. There are two main methods to achieve high-performance or functionalization of polyolefins: chemical crosslinking and reactive grafting. Chemical crosslinking uses the coupling reaction between macromolecular free radicals initiated by peroxide to make polyolefins highly crosslinked, thereby significantly improving their heat resistance, creep resistance, wear resistance and electrical insulation. The cross-linked polyethylene prepared by this method has been widely used in the production of high-voltage cable insulation, pressure-resistant pipes, etc.; the reactive grafting method is to introduce functional groups into the polyolefin chain through the coupling reaction between functional monomer free radicals initiated by peroxide and macromolecular free radicals to achieve different functionalizations. Various maleic anhydride grafted polyolefins produced by this method have been widely used as compatibilizers for polymer blends or composite materials. In the above two modification methods, the oxygen-containing free radicals generated by peroxide at high temperature are essentially used as initiators to trigger the reaction of other free radicals. For example, in the former method, macromolecular free radicals initiated by oxygen-containing free radicals react with each other to form crosslinks; in the latter method, other functional molecules initiated by oxygen-containing free radicals react with macromolecular free radicals.

[0005] In fact, the oxygen-containing free radicals generated by the decomposition of peroxides at high temperatures, in addition to initiating the cross-linking reaction between the above-mentioned macromolecular free radicals and initiating the grafting reaction of other functional substances, also have a part of the oxygen-containing free radicals generated by the decomposition of peroxides at high temperatures directly grafting with macromolecules, that is, in the usual melt processing, polyolefins grafted with oxygen-containing free radicals may also be generated. Using peroxyl free radicals to directly graft with macromolecules may provide new possibilities for the preparation of modified polyolefins using peroxides. Summary of the invention

[0006] The object of the present invention is to provide a polyolefin modified material with fluorescent properties which has low cost, is easy to manufacture and has excellent mechanical properties, and a preparation method thereof.

[0007] The preparation method of the polyolefin modified material provided by the present invention (i.e., the polyolefin modification method) is to add a certain amount of organic peroxide into a polyolefin matrix, without adding any other substances with luminescent properties, adopt a simple melt blending technology, the melt blending temperature is 110-200°C, the time is 5-200 minutes, and the "dynamic" destruction of the cross-linked structure during the melt blending process is utilized. Under dynamic processing conditions, a large amount of peroxide free radicals generated by high-temperature decomposition of organic peroxides are directly grafted onto the polyolefin main chain, and aggregation-induced luminescence is caused by forming extended n-π* and π-π* spatial conjugation, that is, a polyolefin modified material with high fluorescence performance and can be processed by conventional traditional melt processing methods is prepared; wherein, the raw material polyolefin and the organic peroxide are calculated by weight as follows:

[0008] Polyolefin: 100 parts;

[0009] Organic peroxide: 1-10 parts;

[0010] In the present invention, the polyolefin matrix raw material includes various polyolefins, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polypropylene homopolymer (PPH), random copolymer polypropylene (PPR), impact copolymer polypropylene (IPC), ethylene-octene copolymer (EOC), etc., which can be a single polyolefin or a mixture of multiple polyolefins.

[0011] In the present invention, the peroxide includes dibenzoyl peroxide (BPO), dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP) and the like.

[0012] In the present invention, the mass ratio of the polyolefin to the peroxide is 100:(1-10).

[0013] In the present invention, the mass ratio of the polyolefin to the peroxide is more preferably 100:(2-5).

[0014] In the present invention, melt blending is to mix polyolefin and organic peroxide in an internal mixer, an open mixer, a continuous internal mixer, etc. The mixing temperature is 110-200°C and the mixing time is 5-200 minutes depending on the type of raw materials. After the mixing is completed, conventional crushing or granulation operations are performed to obtain a modified polyolefin material with fluorescent function.

[0015] The modified polyolefin material prepared by the present invention has a luminescent function under ultraviolet (UV) excitation. The modified polyolefin material with fluorescent function can be processed by conventional melting processing methods such as conventional extrusion, injection molding, and molding to produce various modified polyolefin products with fluorescent properties.

[0016] Since there are many types of peroxides, a wide range of options are provided for their decomposition to generate peroxy radicals for direct grafting of polyolefins and imparting various functionalities. The present invention selects peroxides containing specific functional groups to directly modify polyolefins, thereby introducing new functional groups on the main chain of polyolefins. When these peroxides contain a large number of functional groups such as carbonyl and ester groups, cluster-induced luminescence may be formed in polyolefins by forming extended n-π* and π-π* spatial conjugation effects, thereby preparing luminescent polyolefin materials. However, there are currently no related attempts to prepare luminescent materials by directly modifying polyolefins with peroxides. This may be because the large-scale introduction of peroxides will form a highly cross-linked structure, causing the polyolefin to lose its melt processability. If in a production process, the degree of cross-linking reaction can be suppressed or the high cross-linking can be destroyed, and at the same time, a large number of groups containing n-π* and π-π* effects can be introduced, it is possible to prepare polyolefin modified materials that have both fluorescent properties and good processability.

[0017] Based on the above ideas, the present invention utilizes the "dynamic" destruction of the cross-linked structure during the melt processing process. Under dynamic processing conditions, a large number of peroxide free radicals generated by the high-temperature decomposition of organic peroxides are directly grafted onto the polyolefin main chain, and aggregation-induced emission caused by the formation of extended n-π* and π-π* spatial conjugation is prepared to prepare a luminescent polyolefin modified material that can be produced and processed by a melt processing method.

[0018] The method for preparing polyolefin luminescent materials (i.e., the method for modifying polyolefin materials) proposed in the present invention is original in academic thinking; compared with the current traditional method of blending polyolefins with rare earth luminescent materials and introducing luminescent materials such as quantum dots and rare earth complexes into polyolefins, it has outstanding substantial characteristics and significant progress. The raw materials used in the present invention are cheap and readily available polyolefins and organic peroxides, the equipment used is ordinary polymer processing equipment, and the production process is conventional melt mixing technology, which does not involve the use and recovery of any solvents. Low raw material cost, convenient manufacturing technology, excellent mechanical properties, especially good flexibility, make the modified polyolefin material of the present invention have broad application prospects in the fields of flexible devices, anti-counterfeiting, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The following are the performance diagrams of the modified polyolefin material prepared in Example 1. (a) is the fluorescence spectrum of the modified polyolefin, (b) is the stress-strain curve, and (c) is the demonstration of the flexible polyolefin product with fluorescence characteristics produced by extrusion, molding and blow molding.

[0020] Figure 2 The fluorescence spectra of the modified polyolefins prepared in Examples 2 and 3 are shown in FIG.

[0021] Figure 3The fluorescence spectra of the modified polyolefins prepared in Examples 4, 5 and 6 are shown in FIG.

[0022] Figure 4 The fluorescence spectra of the modified polyolefins prepared in Examples 7 and 8 are shown in FIG. DETAILED DESCRIPTION

[0023] The present invention is further described below by means of specific embodiments in conjunction with the accompanying drawings, wherein the number of components and contents involved are all measured by mass.

[0024] Example 1: Using polyolefin LDPE and peroxide BPO as raw materials, a mixer was used at 145°C and 50 rpm to melt blend 100 parts of LDPE and 2 parts of BPO (50 g LDPE and 1 g BPO) for 30 minutes to prepare a modified polyolefin material with fluorescent properties. The prepared fluorescent ethylene was observed under ultraviolet light with a wavelength of 365 nm, and the copolymer emitted obvious blue fluorescence. The modified polyolefin was pressed into a film sample at 160°C and 20 MPa, and its fluorescence excitation spectrum was measured. Its fluorescence spectrum showed that the modified polyolefin with fluorescent properties was successfully prepared. The maximum fluorescence absorption peak intensity was 9.6×10 6 au. For the performance diagram of the prepared polyolefin material, see Figure 1 shown.

[0025] In Example 2, the polyolefin used is HDPE, and the rest is the same as in Example 1. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 5.4×10 6 au.

[0026] In Example 3, the polyolefin used is LLDPE, and the rest is the same as in Example 1. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 9.6×10 6 au.

[0027] In Example 4, the polyolefin used is PPH, and the rest is the same as in Example 1. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 4.5×10 6 au.

[0028] In Example 5, the polyolefin used is PPR, and the rest is the same as in Example 1. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 4.2×10 6 au.

[0029] In Example 6, the polyolefin used was EOC, and the rest was the same as in Example 1. The fluorescence results showed that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics was 7.8×10 6 au.

[0030] In Example 7, the peroxide used was DCP, and the rest was the same as in Example 1. The fluorescence results showed that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics was 5.8×10 6 au.

[0031] In Example 8, the peroxide used was DTBP, and the rest was the same as in Example 1. The fluorescence results showed that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics was 1.4×10 6 au.

[0032] In Example 9, the peroxide used was BPO, and the other parts were the same as in Example 1; the dosage was 1 part (50 g LDPE and 0.5 g BPO). The fluorescence results showed that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics was 5.9×10 6 au.

[0033] In Example 10, the peroxide used was BPO, and the other parts were the same as in Example 1; the amount used was 5 parts (50 g LDPE and 0.25 g BPO). The fluorescence results showed that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics was 1.3×10 7 au.

[0034] In Example 11, the peroxide used was BPO, and the other parts were the same as in Example 1; the dosage was 10 parts (50 g LDPE and 2 g BPO). The fluorescence results showed that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics was 2.1×10 7 au.

[0035] Example 12, other aspects are the same as Example 1, the mixing equipment used is a continuous internal mixer, set at 145°C, 50rpm, LDPE and BPO are added in a ratio of 100:2. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 8.9×10 6 au.

[0036] Example 13, other conditions are the same as those in Example 1, except that the mixer temperature is set at 110°C. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 9.1×10 6 au.

[0037] Example 14, other conditions are the same as those of Example 1, except that the mixer temperature is set at 200°C. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 9.7×10 6 au. .

[0038] Example 15, other conditions are the same as those in Example 1, except that the melt mixing time is set to 1 h. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 9.8×10 6 au.

[0039] Example 16, other conditions are the same as those in Example 1, except that the melt mixing time is set to 2 h. The fluorescence results show that the maximum absorption peak intensity of the modified polyolefin with fluorescence characteristics is 9.4×10 6 au.

[0040] The fluorescence spectra of the modified polyolefins prepared in Examples 2 and 3 are shown in Figure 2 .

[0041] The fluorescence spectra of the modified polyolefins prepared in Examples 4, 5 and 6 are shown in Figure 3 .

[0042] The fluorescence spectra of the modified polyolefins prepared in Examples 7 and 8 are shown in Figure 4 .

[0043] The fluorescence spectra and stress-strain properties of the modified polyolefins prepared in other embodiments are similar to those described above.

Claims

1. A method for modifying polyolefins, characterized in that: The method comprises adding an organic peroxide to a polyolefin, and adopting a melt blending technology without adding any other substances having luminescent properties, wherein the melt blending temperature is 110-200°C and the time is 5-200 minutes; during the melt blending process, the peroxide free radicals generated by the high-temperature decomposition of the organic peroxide are directly grafted onto the main chain of the polyolefin, and aggregation-induced luminescence is caused by forming extended n-π* and π-π* spatial conjugation, so that a polyolefin modified material having high fluorescence properties and being able to be processed by conventional traditional melt processing methods is prepared; wherein the raw material polyolefin and the organic peroxide are calculated by weight as follows: Polyolefin: 100 parts; Organic peroxide: 1-10 parts; The organic peroxide is selected from dibenzoyl peroxide, dicumyl peroxide, and di-tert-butyl peroxide.

2. The method for modifying polyolefin according to claim 1, characterized in that: The polyolefin is selected from low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene homopolymer, random copolymer polypropylene, impact copolymer polypropylene, and ethylene-octene copolymer.

3. The method for modifying polyolefin according to claim 1, characterized in that: The mass ratio of the polyolefin to the peroxide is 100:(2-5).

4. The method for modifying polyolefin according to claim 1, characterized in that: The melt blending is performed by using an internal mixer, an open mixer or a continuous internal mixer; after the mixing is completed, a crushing or granulation operation is performed.

5. A polyolefin modified material with fluorescent properties obtained by the modification method according to any one of claims 1 to 4.

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