Preparation method of polymer nanodot ultraviolet absorber and application thereof

Abstract

This invention discloses a method for preparing polymer nanodot ultraviolet absorbers and their applications. The preparation method includes: adding polyethyleneimine to deionized water and sonicating it to complete dissolution at room temperature; adding a first compound to the polyethyleneimine solution and sonicating it to dissolve; stirring the mixture with a magnetic stirrer at 70–100°C for 4–8 hours; cooling the mixture to room temperature after the reaction; dialyzing the reaction solution using a 1000 Da dialysis bag for 2–5 days; removing the dialysate from the dialysis bag; and freeze-drying the dialysate to obtain the polymer nanodot ultraviolet absorber. The polymer nanodot ultraviolet absorber prepared by this invention has good thermal stability, is simple to synthesize, and has a high yield. It can be applied to plastic products such as polyolefins, polyesters, and polyamides, exhibiting excellent light stabilization and anti-aging effects.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, and particularly relates to the preparation method and application of polymer nanodot ultraviolet absorbers. Background Technology

[0002] Plastic materials have become the most widely used and cost-effective materials due to their advantages such as ease of processing, lightweight, flexibility, water resistance, good chemical resistance, and low cost. However, due to the high energy of ultraviolet A (UVA) light (340nm-400nm), which is similar to the CH bond energy, it can break the chemical bonds in organic macromolecules, leading to the decomposition and degradation of plastics. This results in reduced mechanical properties, product discoloration, and shortened service life. Therefore, how to prevent or delay the aging of plastic materials, extend their service life, control the absorption wavelength of organic compounds under ultraviolet irradiation, and prevent UV-induced damage has become a focus of attention for many researchers.

[0003] To improve the resistance to photoaging of plastic materials and extend their service life, adding light stabilizers is considered the most effective and convenient method. Currently used light stabilizers can be categorized into ultraviolet absorbers, excitation quenchers, opacifiers, hydroperoxide decomposers, and free radical scavengers. However, most light stabilizers have drawbacks, such as cumbersome reaction steps, harsh reaction conditions, low yield and purity, highly toxic reducing agents, high cost of heavy metal catalysts and reducing agents, and severe pollution, which greatly limit their application. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing polymer nanodot ultraviolet absorbers and their applications, in order to solve the problems of existing light stabilizers, such as complicated reaction steps, harsh reaction conditions, low yield and purity, high toxicity of reducing agents, high cost of heavy metal catalysts and reducing agents, and serious pollution.

[0005] This invention employs the following technical solution: a method for preparing polymer nanodot ultraviolet absorbers for polymer materials, comprising:

[0006] Polyethyleneimine was added to deionized water and sonicated at room temperature until completely dissolved. The first compound was added to the polyethyleneimine solution and sonicated until dissolved. The mixture was stirred with a magnetic stirrer at 70–100°C for 4–8 hours. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was dialyzed for 2–5 days using a 1000 Da dialysis bag. The dialysate in the dialysis bag was taken out and freeze-dried to obtain the polymer nanodot ultraviolet absorber.

[0007] The first compound is 2,4-dihydroxybenzaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, or p-hydroxybenzaldehyde.

[0008] Furthermore, the mass ratio of polyethyleneimine to the first compound is 2:(0.4-1).

[0009] A polymeric material containing a polymer nanodot ultraviolet absorber, wherein the polymer nanodot ultraviolet absorber is added at a mass fraction of 0.1%-0.5%, and the polymer nanodot ultraviolet absorber is prepared by the above method.

[0010] The beneficial effects of this invention are:

[0011] 1. The polymer nanodot ultraviolet absorber prepared by this invention has good thermal stability, simple synthesis and high yield. It can be applied to plastic products such as polyolefins, polyesters and polyamides. It has excellent light stabilization effect and good anti-aging effect.

[0012] 2. This invention utilizes polyethyleneimine as the basic unit and 2,4-dihydroxybenzaldehyde / o-hydroxybenzaldehyde / m-hydroxybenzaldehyde / p-hydroxybenzaldehyde as modifying groups to synthesize polymer nanodot UV absorbers in one step via Schiff base reaction. The polymer nanodot structure has abundant amino / phenolic functional groups, which then form intramolecular hydrogen bonds. Through the excited-state intramolecular proton transfer mechanism, it promotes non-radiative energy dissipation and exhibits good UV absorption performance.

[0013] 3. The polymer nanodot UV absorber prepared by this invention has good water solubility, strong light resistance, good material compatibility, simple synthesis, and is green and pollution-free.

[0014] 4. The preparation method of the present invention has a simple experimental route, mild conditions, is green and environmentally friendly, safe and reliable, has strong light resistance, and good material compatibility. Attached Figure Description

[0015] Figure 1 The infrared spectrum of the polymer nanodot ultraviolet absorber prepared in Example 1 of this invention;

[0016] Figure 2 The ultraviolet absorption spectrum of the polymer nanodot ultraviolet absorber prepared in Example 1 of this invention;

[0017] Figure 3 These are test graphs showing the mechanical properties of the polymer nanodot UV absorber-doped PE film prepared in Embodiment 1 of this invention at different aging times.

[0018] Figure 3 (a) Elongation at break retention (%) of PE film at different aging times;

[0019] Figure 3 (b) Tensile strength retention rate (%) of PE film at different aging times;

[0020] Figure 4 These are test graphs showing the mechanical properties of the polymer nanodot UV absorber-doped PP film prepared in Embodiment 1 of this invention at different aging times.

[0021] Figure 4 (a) is the elongation at break retention (%) of PP film at different aging times;

[0022] Figure 4 (b) Tensile strength retention rate (%) of PP film at different aging times. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0024] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0025] This invention discloses a method for preparing polymer nanodot ultraviolet absorbers for use in polymer materials, comprising:

[0026] Polyethyleneimine was added to deionized water and sonicated at room temperature until completely dissolved. The first compound was added to the polyethyleneimine solution and sonicated until dissolved. The mixture was stirred with a magnetic stirrer at 70–100°C for 4–8 hours. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was dialyzed for 2–5 days using a 1000 Da dialysis bag. The dialysate in the dialysis bag was taken out and freeze-dried to obtain the polymer nanodot ultraviolet absorber.

[0027] The first compound is 2,4-dihydroxybenzaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, or p-hydroxybenzaldehyde.

[0028] The mass ratio of polyethyleneimine to the first compound is 2:(0.4~1).

[0029] The present invention also discloses a polymeric material containing a polymeric nanodot ultraviolet absorber, wherein the polymeric nanodot ultraviolet absorber is added at a mass fraction of 0.1%-0.5%, and the polymeric nanodot ultraviolet absorber is prepared by the above method.

[0030] Example 1

[0031] Add 4 ml of polyethyleneimine to 40 mL of deionized water and sonicate for 10 min until completely dissolved. Weigh 1.2 g of o-hydroxybenzaldehyde and add it to the polyethyleneimine solution to dissolve by sonication. Stir the mixture with a magnetic stirrer at 70 °C for 4 hours. After the reaction is complete, cool to room temperature and dialyze the reaction solution for 3 days using a 1000 Da dialysis bag. Take out the dialysate from the dialysis bag and freeze-dry it to obtain the polymer nanodot ultraviolet absorber.

[0032] The infrared spectral characteristic absorption peaks of the synthesized polymer nanodot ultraviolet absorber in this embodiment are analyzed as follows: Figure 1 As shown: Compared with the precursor polyethyleneimine, at 1675 cm⁻¹ -1 The appearance of a C=N bond stretching vibration peak indicates the successful synthesis of the polymer nanodot UV absorber.

[0033] The ultraviolet absorption spectrum of the polymer nanodot ultraviolet absorber synthesized in this embodiment is as follows: Figure 2 As shown, the polymer nanodot UV absorber exhibits strong absorption in the wavelength range of 200-400 nm, and its intensity is significantly stronger than that of the raw material, indicating that it has good UV absorption performance and is a UV absorber with application potential.

[0034] Example 2

[0035] Add 4 ml of polyethyleneimine to 40 mL of deionized water and sonicate for 10–20 min until completely dissolved. Weigh 1.2 g of m-hydroxybenzaldehyde and add it to the polyethyleneimine solution to dissolve by sonication. Stir the mixture with a magnetic stirrer at 70 °C for 4 hours. After the reaction is complete, cool to room temperature and dialyze the reaction solution for 3 days using a 1000 Da dialysis bag. Remove the dialysate from the dialysis bag and freeze-dry it to obtain the polymer nanodot UV absorber.

[0036] The characteristic absorption peaks of the infrared spectrum of the polymer nanodot ultraviolet absorber synthesized in this embodiment are analyzed as follows: Compared with the precursor polyethyleneimine, the peak at 1667 cm⁻¹ is... -1 The appearance of a C=N bond stretching vibration peak indicates the successful synthesis of the polymer nanodot UV absorber.

[0037] Example 3

[0038] Add 4 ml of polyethyleneimine to 40 mL of deionized water and sonicate for 10–20 min until completely dissolved. Weigh 1.2 g of 2,4-dihydroxybenzaldehyde and add it to the polyethyleneimine solution, sonicate to dissolve, and stir with a magnetic stirrer at 90 °C for 5 hours. After the reaction is complete, cool to room temperature and dialyze the reaction solution for 3 days using a 1000 Da dialysis bag. Take out the dialysate from the dialysis bag and freeze-dry it to obtain the polymer nanodot ultraviolet absorber.

[0039] The characteristic absorption peaks of the infrared spectrum of the polymer nanodot ultraviolet absorber synthesized in this embodiment are analyzed as follows: Compared with the precursor polyethyleneimine, the peak at 1674 cm⁻¹ is... -1 The appearance of a C=N bond stretching vibration peak indicates the successful synthesis of the polymer nanodot UV absorber.

[0040] Example 4

[0041] Add 4 ml of polyethyleneimine to 40 mL of deionized water and sonicate for 10–20 min until completely dissolved. Weigh 1.2 g of p-hydroxybenzaldehyde and add it to the polyethyleneimine solution to dissolve by sonication. Stir the mixture with a magnetic stirrer at 90 °C for 5 hours. After the reaction is complete, cool to room temperature and dialyze the reaction solution for 3 days using a 1000 Da dialysis bag. Remove the dialysate from the dialysis bag and freeze-dry it to obtain the polymer nanodot UV absorber.

[0042] The characteristic absorption peaks of the infrared spectrum of the polymer nanodot ultraviolet absorber synthesized in this embodiment are analyzed as follows: Compared with the precursor polyethyleneimine, the peak at 1667 cm⁻¹ is... -1 The appearance of a C=N bond stretching vibration peak indicates the successful synthesis of the polymer nanodot UV absorber.

[0043] Example 5

[0044] The polymer nanodot UV absorber prepared in Example 1 was doped into PP and PE materials at mass fractions of 0.1%, 0.3%, and 0.5% to prepare PE and PP films, and then photoaging experiments were conducted on the PE and PP films.

[0045] The mechanical properties of the polymer nanodot UV absorber synthesized in Example 1, doped into the PE film at different aging times, are shown in the following figures. Figure 3 As shown, the mechanical properties of PE films with added 0.1%, 0.3%, and 0.5% polymer nanodot UV absorbers are stronger than those of blank PE films, indicating that polymer nanodot UV absorbers exhibit better anti-aging properties and can effectively inhibit the degradation of PE materials.

[0046] The mechanical properties of the polymer nanodot UV absorber synthesized in Example 1, incorporated into PP film at different aging times, are shown in the following figures. Figure 4 As shown, the mechanical properties of PP films with added 0.1%, 0.3%, and 0.5% polymer nanodot UV absorbers are stronger than those of blank PP films, indicating that polymer nanodot UV absorbers exhibit better anti-aging properties and can effectively inhibit the degradation of PP materials.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polymeric material containing a polymeric nanodot ultraviolet absorber, wherein the polymeric nanodot ultraviolet absorber is added at a mass fraction of 0.1%-0.5%; The preparation method of the polymer nanodot ultraviolet absorber includes: Polyethyleneimine was added to deionized water and sonicated at room temperature until completely dissolved. The first compound was added to the polyethyleneimine solution and sonicated until dissolved. The mixture was stirred with a magnetic stirrer at 70-100°C for 4-8 hours. After the reaction was completed, the mixture was cooled to room temperature. The reaction solution was dialyzed for 2-5 days using a 1000 Da dialysis bag. The dialysate in the dialysis bag was taken out and freeze-dried to obtain the polymer nanodot ultraviolet absorber. The first compound is 2,4-dihydroxybenzaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, or p-hydroxybenzaldehyde.

2. The polymeric material containing polymer nanodot ultraviolet absorbers according to claim 1, characterized in that, in, The mass ratio of polyethyleneimine to the first compound is 2:(0.4~1).

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