Bio-based polyurethane photo-thermal conversion elastomer as well as preparation method and application thereof

Abstract

The invention discloses a bio-based polyurethane photo-thermal conversion elastomer as well as a preparation method and application thereof. The elastomer is prepared by taking castor oil and isophorone diisocyanate as substrates, and introducing 4, 4 '-diaminodiphenyl disulfide as a chain extender and polyphenol lignin as a functional filler. The preparation method comprises the following steps: reacting castor oil with isophorone diisocyanate under the action of a catalyst to generate a prepolymer; then sequentially adding 4, 4 '-diaminodiphenyl disulfide and polyphenol lignin according to a specific proportion to carry out chain extension and modification reaction; and finally, pouring the obtained polymer into a mold, and heating, curing and molding. The method is simple in process and mild in condition. The prepared elastomer has a dual dynamic cross-linked network of dynamic disulfide bonds and multiple hydrogen bonds, not only shows good mechanical properties, self-repairability and shape memory effect, but also has excellent photothermal conversion efficiency and ultraviolet barrier ability due to the inherent pi-pi conjugated structure of lignin; the material can be widely applied to the fields of flexible electronics, ultraviolet protection, photo-thermal-photoelectric conversion devices and the like.

Description

Technical Field

[0001] This invention belongs to the field of bio-based elastomer technology, specifically relating to a bio-based polyurethane photothermal conversion elastomer, its preparation method, and its application. Background Technology

[0002] Polyurethane, with its unique molecular structure and excellent mechanical properties, has become one of the most in-demand polymers in society today, showing great promise in emerging fields such as aerospace, soft robotics, and flexible electronics. In recent years, to meet the growing demand for sustainable and intelligent materials, the development of self-healing and recyclable polyurethanes has become a cutting-edge hot topic in materials science. With the rapid development of bio-based materials, bio-based polyurethane elastomers with dynamic covalent bonds have become a research hotspot and have made significant progress. The core of this approach is to partially or completely replace traditional petroleum-based raw materials with biomass resources (such as vegetable oils and lignin derivatives). Castor oil, due to its low toxicity, biodegradability, cost-effectiveness, and non-edible nature, has become an excellent alternative to petrochemical raw materials. Castor oil has unique hydroxyl groups that can act as a natural biomass-based polyol, directly reacting with isocyanates to generate polyurethane. However, research on bio-based polyurethanes still faces many shortcomings. First, their "bio-based" content is generally low, and their biodegradability is limited, meaning they are not entirely environmentally friendly. Second, a single dynamic network cannot simultaneously meet the synergistic requirements of high mechanical strength and rapid self-healing, and the random breakage of dynamic bonds can easily lead to material fatigue failure.

[0003] Bio-based polyurethane-based photothermal conversion materials have attracted considerable attention due to their environmentally friendly and energy-saving properties, as well as their ease of acquisition. Photothermal agents, such as carbon-based materials and semiconductor metal oxides, are typically combined with polyurethane to impart photothermal response properties to polyurethane materials. Despite significant progress, several challenges remain, such as the uniform and stable dispersion of photothermal agents within the polyurethane matrix and the high cost of efficient photothermal agents. Lignin, as the second most abundant natural aromatic polymer, offers unique advantages for the reinforcement, modification, and functionalization of polymer materials due to its polyhydroxy, phenyl, and π-π stacking structures. Unlike polyurethane-based composites that require the addition of exogenous materials (such as CNTs or noble metals), lignin itself is a natural photothermal agent, and the π-π conjugated structure in lignin molecules endows it with excellent photothermal conversion effects. This invention uses castor oil and polyphenolized lignin as raw materials to prepare a high-bio-based polyurethane elastomer containing dynamic disulfide bonds and multiple hydrogen bonds, which can be used in photothermal-photoelectric conversion, ultraviolet shielding, and other fields. Summary of the Invention

[0004] Technical problem solved: This invention provides a bio-based polyurethane photothermal conversion elastomer, its preparation method and application. The prepared bio-based elastomer not only has a high bio-based content and excellent mechanical properties, but also has recyclability, shape memory and self-healing properties, and can be directly used for photothermal conversion.

[0005] Technical solution: A method for preparing a bio-based polyurethane photothermal conversion elastomer, comprising the following steps: (1) mixing castor oil, isophorone diisocyanate and catalyst, and reacting at 50-60°C for 1-2 hours to obtain a castor oil-based isocyanate intermediate; (2) adding 4,4'-diaminodiphenyl disulfide and polyphenolized lignin sequentially to the intermediate obtained in step (1), and continuing to react at 50-60°C for 2-4 hours to obtain a polyphenolized lignin-modified castor oil-based polyurethane polymer; wherein, the amount of 4,4'-diaminodiphenyl disulfide is 29%-49% of the mass of castor oil, and the amount of polyphenolized lignin is 2%-8% of the mass of castor oil; (3) transferring the polymer obtained in step (2) into a mold and curing at 70-80°C for 10 hours to obtain the bio-based polyurethane photothermal conversion elastomer.

[0006] Preferably, the catalyst in step (1) is an organotin catalyst. The organotin catalyst is dibutyltin dilaurate.

[0007] Preferably, the reaction temperature in step (1) is 55°C and the reaction time is 1.5 hours.

[0008] The aforementioned polyphenolized lignin is lignin that has undergone phenolic modification. This phenolic modification involves protecting the phenolic hydroxyl groups with terephthalic aldehyde followed by phenolic modification.

[0009] A bio-based polyurethane photothermal conversion elastomer is prepared by the above-described method.

[0010] A bio-based polyurethane photothermal conversion elastomer comprises a flexible aliphatic chain structure derived from castor oil, dynamic disulfide bonds introduced by 4,4'-diaminodiphenyl disulfide, and a rigid benzene ring structure and π-π conjugated structure provided by polyphenolized lignin.

[0011] The above-mentioned bio-based polyurethane photothermal conversion elastomer is used in the preparation of ultraviolet blocking materials.

[0012] The above-mentioned bio-based polyurethane photothermal conversion elastomer is used in photothermal-photoelectric conversion devices.

[0013] Beneficial effects: This invention uses castor oil and modified lignin, widely available bio-based resources, as the main raw materials to prepare bio-based polyurethane photothermal conversion elastomers, reducing dependence on and consumption of petrochemical resources; the polyurethane structure simultaneously introduces dynamic disulfide bonds and multiple hydrogen bonds, endowing the polyurethane elastomer with excellent self-healing properties, shape memory, and recyclability; the polymer structure contains the flexible aliphatic chain structure of castor oil and the rigid benzene ring structure of 4,4'-diaminodiphenyl disulfide and lignin, resulting in materials with good mechanical properties; the π-π conjugated structure in the bio-based polyurethane endows the polyurethane elastomer with excellent photothermal conversion effect and UV resistance. Attached Figure Description

[0014] Figure 1 Infrared spectra of castor oil-based isocyanate intermediates and products, including bio-based polyurethane prepolymers.

[0015] Figure 2 The temperature change of bio-based polyurethane photothermal conversion elastomer under different light intensities.

[0016] Figure 3 Bio-based polyurethane photothermal conversion elastomer at 0.4 W / cm 2 Temperature changes during four on / off cycles of xenon light irradiation.

[0017] Figure 4 UV blocking rate of bio-based polyurethane photothermal conversion elastomer. Detailed Implementation

[0018] The following embodiments are merely illustrative of the invention and should not be construed as limiting the scope or content of the invention. The invention will be further described in detail below with reference to specific embodiments.

[0019] Example 1

[0020] 10.3 g of castor oil, 4.5 g of isophorone diisocyanate, and 3 drops of dibutyltin dilaurate were added to a four-necked flask and reacted at 55 °C for 1.5 h to obtain a castor oil-based isocyanate intermediate. Then, 3.2 g of 4,4'-diaminodiphenyl disulfide and 0.2 g of polyphenolized lignin were added sequentially, and the reaction was continued at 55 °C for 2 h to obtain a polyphenolized lignin-modified castor oil-based polyurethane polymer. The prepared polyphenolized lignin-modified castor oil-based polyurethane polymer was transferred to a polypropylene mold and heated in an oven at 70 °C for 10 h to obtain a bio-based polyurethane photothermal conversion elastomer. Figure 1 Infrared spectra of castor oil-based isocyanate intermediates and products, including bio-based polyurethane prepolymers.

[0021] Example 2

[0022] 10.3 g of castor oil, 4.5 g of isophorone diisocyanate, and 3 drops of dibutyltin dilaurate were added to a four-necked flask and reacted at 55 °C for 1.5 h to obtain a castor oil-based isocyanate intermediate. Then, 3.0 g of 4,4'-diaminodiphenyl disulfide and 0.4 g of polyphenolized lignin were added sequentially, and the reaction was continued at 55 °C for 3 h to obtain a polyphenolized lignin-modified castor oil-based polyurethane polymer. The prepared polyphenolized lignin-modified castor oil-based polyurethane polymer was transferred to a polypropylene mold and heated in an oven at 70 °C for 10 h to obtain a bio-based polyurethane photothermal conversion elastomer. Figure 2 The temperature variation of the bio-based polyurethane photothermal conversion elastomer under different light intensities is shown. The results indicate that the maximum temperature of this bio-based polyurethane photothermal conversion elastomer can reach above 150 °C, and the maximum temperature of the film can be precisely controlled by adjusting the lignin content and light intensity. This excellent photothermal conversion performance is attributed to the strong light absorption capacity conferred by the lignin π-π conjugated structure.

[0023] Example 3

[0024] 10.3 g of castor oil, 4.5 g of isophorone diisocyanate, and 3 drops of dibutyltin dilaurate were added to a four-necked flask and reacted at 55 °C for 1.5 h to obtain a castor oil-based isocyanate intermediate. Then, 2.5 g of 4,4'-diaminodiphenyl disulfide and 0.6 g of polyphenolized lignin were added sequentially, and the reaction was continued at 55 °C for 4 h to obtain a polyphenolized lignin-modified castor oil-based polyurethane polymer. The prepared polyphenolized lignin-modified castor oil-based polyurethane polymer was transferred to a polypropylene mold and heated in an oven at 80 °C for 10 h to obtain a bio-based polyurethane photothermal conversion elastomer. Figure 3 Bio-based polyurethane photothermal conversion elastomer at 0.4 W / cm 2 Temperature changes under four on / off cycles of xenon light irradiation. At 1.2 W·cm -2 Four switching cycles were conducted under light intensity, and the highest temperature of the thin film remained stable throughout the multiple cycles, confirming its excellent photothermal conversion stability.

[0025] Example 4

[0026] 10.3 g of castor oil, 4.5 g of isophorone diisocyanate, and 3 drops of dibutyltin dilaurate were added to a four-necked flask and reacted at 55 °C for 1.5 h to obtain a castor oil-based isocyanate intermediate. Then, 2.1 g of 4,4'-diaminodiphenyl disulfide and 0.8 g of polyphenolized lignin were added sequentially, and the reaction was continued at 55 °C for 4 h to obtain a polyphenolized lignin-modified castor oil-based polyurethane polymer. The prepared polyphenolized lignin-modified castor oil-based polyurethane polymer was transferred to a polypropylene mold and heated in an oven at 80 °C for 10 h to obtain a bio-based polyurethane photothermal conversion elastomer. The aromatic ring, due to its unique electronic and chemical structure, possesses UV resistance. The UV blocking rates of the above examples were compared. Figure 4 The value of the UV blocking rate of the bio-based polyurethane photothermal conversion elastomer indicates that it has a strong UV blocking ability.

[0027] The present invention is not limited to the above embodiments; all embodiments described herein can be implemented and have the aforementioned good effects.

Claims

1. A method for preparing a bio-based polyurethane photothermal conversion elastomer, characterized in that, The process includes the following steps: (1) Mixing castor oil, isophorone diisocyanate and catalyst, and reacting at 50-60°C for 1-2 hours to obtain a castor oil-based isocyanate intermediate; (2) Adding 4,4'-diaminodiphenyl disulfide and polyphenolized lignin sequentially to the intermediate obtained in step (1), and continuing to react at 50-60°C for 2-4 hours to obtain a polyphenolized lignin-modified castor oil-based polyurethane polymer; wherein the amount of 4,4'-diaminodiphenyl disulfide is 29%-49% of the mass of castor oil, and the amount of polyphenolized lignin is 2%-8% of the mass of castor oil; (3) Transferring the polymer obtained in step (2) into a mold and curing at 70-80°C for 10 hours to obtain the bio-based polyurethane photothermal conversion elastomer.

2. The preparation method according to claim 1, characterized in that, The catalyst mentioned in step (1) is an organotin catalyst.

3. The preparation method according to claim 2, characterized in that, The organotin catalyst is dibutyltin dilaurate.

4. The preparation method according to claim 1, characterized in that, In step (1), the reaction temperature is 55℃ and the reaction time is 1.5 hours.

5. The preparation method according to claim 1, characterized in that, The polyphenolized lignin is lignin that has undergone phenolic modification.

6. The preparation method according to claim 5, characterized in that, The phenolic modification involves protecting the phenolic hydroxyl groups with terephthalic aldehyde and then performing phenolic modification.

7. A bio-based polyurethane photothermal conversion elastomer, characterized in that, It is prepared by any one of claims 1 to 6.

8. A bio-based polyurethane photothermal conversion elastomer, characterized in that, The elastomer comprises a flexible aliphatic chain structure derived from castor oil, dynamic disulfide bonds introduced by 4,4'-diaminodiphenyl disulfide, and a rigid benzene ring structure and π-π conjugated structure provided by polyphenolized lignin.

9. The application of the bio-based polyurethane photothermal conversion elastomer according to claim 7 or 8 in the preparation of ultraviolet blocking materials.

10. The application of the bio-based polyurethane photothermal conversion elastomer according to claim 7 or 8 in a photothermal-photoelectric conversion device.

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