A bio-based furan ring-containing polysiloxane fluorescent material and a preparation method thereof

Abstract

The application discloses a kind of containing bio-based furan ring polysiloxane fluorescent material and preparation method thereof, belong to polymer luminescent material field.In the application, different silane coupling agent, bio-based 2,5-furan dimethyl alcohol and different carbon chain length aliphatic dihydric alcohol are prepared to polysiloxane fluorescent material by ester exchange polycondensation reaction.In the application, by adjusting the molar ratio of rigid 2,5-furan dimethyl alcohol and aliphatic dihydric alcohol monomer, and the kind of silane coupling agent and aliphatic dihydric alcohol monomer, different structure containing bio-based furan ring polysiloxane fluorescent material is prepared;Bio-based 2,5-furan dimethyl alcohol introduced in the application, not only can adjust the rigidity and flexibility of polysiloxane structure, but also can promote the formation of space n-n and n-pi interaction, expand the delocalization range of electron, make its emission wavelength red shift to green fluorescent range (500nm-570nm);Simple synthesis process is conducive to large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of polymer luminescent materials, and relates to a bio-based furan cyclic polysiloxane fluorescent material and its preparation method, specifically to a bio-based furan cyclic polysiloxane fluorescent material that emits green fluorescence and its preparation method. Background Technology

[0002] Organic fluorescent materials have wide applications in optoelectronics, chemical sensing, and bioimaging. In recent years, non-traditional fluorescent polymers lacking conjugated π-electron units have attracted increasing attention due to their unique photophysical properties. Typically, these polymer molecules contain a large number of lone-pair heteroatoms (N, O, S, P) and unsaturated bonds such as amides, esters, carbonyls, cyanos, imines, or carbon-carbon double bonds, giving them excellent biocompatibility, environmental friendliness, simple synthesis, and easily tunable structures. Compared to traditional organic fluorescent materials, these fluorescent polymers exhibit a significant aggregation-induced emission (AIE) effect, thus offering greater advantages in cell imaging, data anti-counterfeiting, and metal ion detection.

[0003] Polysiloxanes, as fluorescent polymers, exhibit flexible Si-OC bonds that promote polymer chain aggregation and the formation of unconventional luminescent clusters, enhancing spatial n-π and n-π interactions. Conversely, this flexibility leads to higher polymer chain segment mobility, making energy more easily dissipated through nonradiative transitions, thus reducing radiative transitions. Yan et al. (Angew. Chem. Int. Ed., 2023, 62: e202312571) reported the construction of Si-OB hybrid backbone polymers using tetraethyl orthosilicate-functionalized hyperbranched borosilicate esters. With increasing electron density of the diol monomer, the optimal emission wavelength of the prepared hyperbranched polyborosilicate significantly redshifted from 510 nm to 640 nm, due to the synergistic effect of electron delocalization induced by the dual heteroatoms (B and Si) and spatial n-π interactions. Yan et al. (J. Mater. Chem. B, 2025, 13(37), 11687-11695) prepared hyperbranched polysiloxanes with polar unsaturated imine groups (C=N) as side chains, whose emission wavelength could be redshifted to 620 nm. This was mainly attributed to the spatial proximity of adjacent C=N groups, forming spatial nn, n-π, and dipole-dipole interactions. These multiple interactions not only extended the delocalization range of electrons but also rigidified the molecular conformation. Although some progress has been made in long-wavelength fluorescence emission of non-traditional fluorescent polymers reported so far, the fluorescence intensity of these polymers in dilute solutions is low, and they typically emit blue fluorescence, thus limiting their application in fields such as bioimaging. Therefore, the design and synthesis of long-wavelength emission non-traditional fluorescent polymers are of great significance for expanding their application areas and deepening the understanding of fluorescence mechanisms.

[0004] Chinese patent CN117247546A discloses an aggregation-induced emission hyperbranched polysiloxane and its preparation method, using transesterification polymerization to prepare the material. However, its emission wavelength is concentrated in the ultraviolet region (378 nm), resulting in poor material performance. Chinese patent CN107652318A discloses an acryloyloxyethoxysiloxane monomer and a silicon-containing hyperbranched polyurethane fluorescent material and its preparation method, using Michael addition polymerization to synthesize the material. Its fluorescence emission wavelength is located in the blue light region (460 nm), and overall, the material performance is better, but the preparation cycle is long, which is not conducive to large-scale production. The above patents involve polysiloxane fluorescent materials, which contribute to the development of new fluorescent materials, but the performance of these fluorescent materials still has certain limitations.

[0005] In view of the above problems, the present invention develops a bio-based furan cyclic polysiloxane fluorescent material and its preparation method. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, such as long material preparation cycles, poor material performance, and low fluorescence intensity, this invention provides a bio-based furan-cyclic polysiloxane fluorescent material and its preparation method. The method utilizes bio-based 2,5-furandiethanol, a renewable resource, as a rigid monomer, and selects aliphatic diols with different carbon chain lengths as flexible monomers. Polysiloxane materials are prepared through a one-pot transesterification polymerization reaction with different silane coupling agents. The synthetic route of the bio-based polysiloxane prepared by this method is simple, easy to scale up, and allows for flexible adjustment of fluorescence properties through molecular design. The prepared material emits green fluorescence in solution. The 2,5-furandiethanol introduced into the polysiloxane structure not only helps to enhance the n-π and nn interactions in space but also effectively regulates the rigidity of the molecular conformation, thereby improving its fluorescence performance.

[0007] This invention provides a bio-based furan-cyclic polysiloxane fluorescent material, prepared by transesterification polycondensation reaction of different silane coupling agents, bio-based 2,5-furandiethanol, and aliphatic diols with different carbon chain lengths; its structure is as follows: ;

[0008] or ;

[0009] In the hyperbranched polysiloxane structural formula, R1 is one of amino, ethylenediamine, (CH3)2C=N–, or tertiary amine; R2 is one of straight-chain alkyl with a carbon chain length of 3-6, -CH2CH(CH3)CH2-, -CH2C(CH3)2CH2-, -CH2CH2NHCH2CH2-, –CH2CH2N(CH3)CH2CH2–, –CH2CH2OCH2CH2–, or 1,4-cyclohexyl. In the structural formula of linear polysiloxane, R3 is one of amino, ethylenediamine, or (CH3)2C=N–; R2 is one of a straight-chain alkyl group with a carbon chain length of 3-6, –CH2CH(CH3)CH2–, –CH2C(CH3)2CH2–, –CH2CH2NHCH2CH2–, –CH2CH2N(CH3)CH2CH2–, –CH2CH2OCH2CH2–, or 1,4-cyclohexyl.

[0010] The aliphatic diols with different carbon chain lengths are one of 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, diethanolamine, N-methyldiethanolamine, diethylene glycol, and 1,4-cyclohexanediol. The silane coupling agent is one of 3-aminopropyltrimethoxysilane, N,N-dimethyl-3-aminopropyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]propyl-2-imine, γ-aminoethylaminopropyltrimethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, aminopropylmethyldimethoxysilane, and N-(3-(dimethoxysilyl)propyl)propyl-2-imine.

[0011] The above-mentioned raw material selection methods involve using a trifunctional silane coupling agent to prepare a bio-based furan-cyclic polysiloxane with a hyperbranched structure, or using a difunctional silane coupling agent to prepare a bio-based furan-cyclic polysiloxane with a linear structure.

[0012] When the flexible carbon chain length of the polysiloxane is shortened and there is no sterically hindered methyl group, the emission wavelength of the polymer exhibits a significant redshift to 500 nm–570 nm. The shorter flexible carbon chain promotes the formation of spatially unconventional luminescent clusters, thereby creating enhanced spatial interactions and resulting in the redshift.

[0013] This invention is prepared by transesterification polycondensation reaction using different silane coupling agents and 2,5-furandiethanol and aliphatic diols with different carbon chain lengths in a certain molar ratio.

[0014] This invention enables the preparation of polysiloxanes with different structures by adjusting the types of aliphatic diols and silane coupling agents. As the carbon chain length decreases, the fluorescence properties of the polymer increase. Aliphatic diols, as flexible monomers, can adjust the rigidity and flexibility of the product. Flexibility of the material is conducive to the formation of non-traditional luminescent clusters, while rigidity helps stabilize existing clusters. However, excessively flexible or rigid chain structures are detrimental to cluster formation. The furan ring in 2,5-furandimethyl alcohol possesses aromaticity, providing delocalized π electrons and forming enhanced spatial n-π interactions. Meanwhile, the O atoms containing lone pairs of electrons form n-n interactions, and the aliphatic diol adjusts the rigidity and flexibility of the molecular conformation, promoting the emission of long-wavelength fluorescence. Different siloxane monomers provide side groups rich in n or π electrons, further enhancing spatial interactions.

[0015] This invention provides a method for preparing the above-mentioned bio-based furan-cyclic polysiloxane fluorescent material, comprising the following steps: Step 1: Mix the silane coupling agent, 2,5-furandiethanol and aliphatic diol in a molar ratio of 1:0.1~1:0.1~1; Step 2: Under nitrogen protection, an oil bath is used for heating at a temperature of 90 ℃~110 ℃, and the reaction temperature is gradually increased to 110 ℃~180 ℃ in 10 ℃ increments. The byproduct methanol generated during the reaction is continuously removed by atmospheric distillation to promote the polymerization reaction to the forward direction and increase the yield.

[0016] Step 3: After the reaction is complete, the mixture is cooled to room temperature, ethanol is added to completely dissolve it, and then dialysis is performed for purification. The solvent in the resulting solution is removed by rotary evaporation and then dried in a vacuum oven at 60 °C for 24 h to obtain bio-based furan cyclopolysiloxane fluorescent material.

[0017] Preferably, the molar ratio of the silane coupling agent, 2,5-furandiethanol and aliphatic diol is 1:0.9:0.9.

[0018] The beneficial effects of this invention are: (1) By adjusting the molar ratio of rigid 2,5-furandiethanol to aliphatic diol monomers, as well as the types of silane coupling agents and aliphatic diol monomers, this invention prepares bio-based furan cyclic polysiloxane fluorescent materials with different structures.

[0019] (2) Compared with non-traditional luminescent polymers, the bio-based 2,5-furandimethyl alcohol introduced in this invention can not only adjust the rigidity and flexibility of the polysiloxane structure, but also promote the formation of spatial n-π and n-π interactions, expand the delocalization range of electrons, and make its emission wavelength red-shift to the green fluorescence range (500nm~570nm).

[0020] (3) The monomer raw materials used in this invention are sustainable, the synthesis process is simple and environmentally friendly, which is conducive to large-scale production. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the synthetic route for the bio-based furan-cyclic polysiloxane fluorescent material of the present invention; Figure 2 A schematic diagram of the synthetic route for bio-based furan ring linear polysiloxane fluorescent materials; Figure 3 Fluorescence spectrum of the bio-based furan cyclic polysiloxane solution prepared in Example 1 (concentration: 20 mg / mL). Figure 4 The fluorescence spectrum of the bio-based furan-cyclic polysiloxane prepared in Example 2 in its pure state; Figure 5 The image shows a fluorescence photograph of the bio-based furan-cyclic polysiloxane solution prepared in Example 2. Figure 6Fluorescence comparison images of bio-based furan cyclopolysiloxane solutions prepared for Examples 1 (P1), 2 (P2), and 4 (P3). Detailed Implementation

[0022] This invention provides a bio-based furan-ring polysiloxane fluorescent material, successfully prepared via transesterification polymerization using different silane coupling agents, 2,5-furandiethanol, and aliphatic diols in specific molar ratios. Different polysiloxanes can be prepared by adjusting the types of aliphatic diols and silane coupling agents. The fluorescence performance is enhanced with shorter carbon chain lengths. The furan ring in 2,5-furandiethanol possesses aromaticity, providing delocalized π electrons and forming enhanced spatial n-π interactions. The lone pair O atom and N atom form n-n interactions, and the aliphatic diol modulates the rigidity and flexibility of the molecular conformation, promoting long-wavelength fluorescence emission. Introducing n or π electrons into the siloxane monomer further enhances the spatial n-n and n-π interactions. Polysiloxanes possess advantages such as being green and sustainable, having a simple synthesis process, tunable structure, and high quantum yield, showing potential applications in data anti-counterfeiting, metal ion detection, and bioimaging.

[0023] The present invention will be further described below with reference to the embodiments, which include, but are not limited to, the following embodiments.

[0024] Example 1 γ-aminoethylaminopropyltrimethoxysilane, bio-based 2,5-furandiethanol, and 1,3-propanediol were mixed in a molar ratio of 1:0.9:0.9. Under nitrogen protection, the mixture was heated to 100 °C to initiate the reaction. The temperature was gradually increased in 10 °C increments. During the reaction, the generated small-molecule methanol was removed by high-pressure distillation to promote the polymerization reaction. The final reaction temperature was 130 °C. After the reaction, the mixture was cooled to room temperature, dissolved in ethanol, purified by dialysis, and the ethanol was removed by rotary evaporation. The mixture was then dried in a vacuum oven at 60 °C for 24 h to obtain the bio-based furan cyclic polysiloxane fluorescent material.

[0025] Example 2 γ-aminoethylaminopropyltrimethoxysilane, bio-based 2,5-furandimethylethanol, and 1,4-butanediol were mixed in a molar ratio of 1:0.9:0.9. Under nitrogen protection, the mixture was heated to 100 °C to initiate the reaction. The temperature was gradually increased in 10 °C increments. During the reaction, the generated small-molecule methanol was removed by high-pressure distillation to promote the polymerization reaction. The final reaction temperature was 140 °C. After the reaction, the mixture was cooled to room temperature, dissolved in ethanol, purified by dialysis, and the ethanol was removed by rotary evaporation. The mixture was then dried in a vacuum oven at 60 °C for 24 h to obtain the bio-based furan cyclic polysiloxane fluorescent material.

[0026] Example 3 N,N-Dimethyl-3-aminopropyltrimethoxysilane, bio-based 2,5-furandimethylethanol, and 1,5-pentanediol were mixed in a molar ratio of 1:0.6:0.12. Under nitrogen protection, the mixture was heated to 100 °C to initiate the reaction. The temperature was gradually increased in 10 °C increments. During the reaction, the generated small-molecule methanol was removed by high-pressure distillation to promote the polymerization reaction. The final reaction temperature was 150 °C. After the reaction, the mixture was cooled to room temperature, dissolved in ethanol, purified by dialysis, and the ethanol was removed by rotary evaporation. The mixture was then dried in a vacuum oven at 60 °C for 24 h to obtain a bio-based furan cyclic polysiloxane fluorescent material.

[0027] Example 4 γ-aminoethylaminopropyltrimethoxysilane, bio-based 2,5-furandiethanol, and 2-methyl-1,3-propanediol were mixed in a molar ratio of 1:0.9:0.9. Under nitrogen protection, the mixture was heated to 100 °C to initiate the reaction. The temperature was gradually increased in 10 °C increments. During the reaction, the generated small-molecule methanol was removed by high-pressure distillation to promote the polymerization reaction. The final reaction temperature was 150 °C. After the reaction, the mixture was cooled to room temperature, dissolved in ethanol, purified by dialysis, and the ethanol was removed by rotary evaporation. The mixture was then dried in a vacuum oven at 60 °C for 24 h to obtain the bio-based furan cyclic polysiloxane fluorescent material.

[0028] Example 5 N-[3-(trimethoxysilyl)propyl]propyl-2-imine, bio-based 2,5-furandimethyl alcohol, and 1,4-butanediol were mixed in a molar ratio of 1:0.12:0.6. Under nitrogen protection, the mixture was heated to 90 °C to initiate the reaction. The temperature was gradually increased in 10 °C increments. During the reaction, the generated small-molecule methanol was removed by high-pressure distillation to promote the polymerization reaction. The final reaction temperature was 170 °C. After the reaction, the mixture was cooled to room temperature, dissolved in ethanol, purified by dialysis, and the ethanol was removed by rotary evaporation. The mixture was then dried in a vacuum oven at 60 °C for 24 h to obtain a bio-based furan cyclic polysiloxane fluorescent material.

[0029] Example 6 Aminaminopropylmethyldimethoxysilane, bio-based 2,5-furandimethylethanol, and 1,6-hexanediol were mixed in a molar ratio of 1:0.4:0.8. Under nitrogen protection, the mixture was heated to 110 °C to initiate the reaction. The temperature was gradually increased in 10 °C increments. During the reaction, the generated small-molecule methanol was removed by high-pressure distillation to promote the polymerization reaction. The final reaction temperature was 180 °C. After the reaction, the mixture was cooled to room temperature, dissolved in ethanol, purified by dialysis, and the ethanol was removed by rotary evaporation. The mixture was then dried in a vacuum oven at 60 °C for 24 h to obtain a bio-based furan cyclic polysiloxane fluorescent material.

[0030] The bio-based furan-cyclic polysiloxane fluorescent material prepared in this invention has the following synthetic route: Figure 1 As shown (corresponding to Examples 1-5), the silane coupling agent used is trifunctional, and the prepared bio-based furan-cyclic polysiloxane has a hyperbranched structure; the synthetic route of the bio-based furan-cyclic polysiloxane fluorescent material is as follows: Figure 2 As shown (corresponding to Example 6), the silane coupling agent used is difunctional, and the prepared bio-based furan-cyclic polysiloxane has a linear structure. The molar ratio of the silane coupling agent, bio-based 2,5-furandiethanol, and aliphatic diol is 1:0.1~1:0.1~1, and it is prepared by transesterification polycondensation reaction.

[0031] Performance tests were conducted on the products obtained in the examples. For example... Figures 3-6 As shown. The fluorescence properties of the samples in both pure and solution states were tested using a Hitachi F-2700 instrument, with an excitation and emission slit width of 5 nm.

[0032] Figure 3 The fluorescence spectrum (concentration: 20 mg / mL) of the bio-based furan-cyclic polysiloxane solution prepared in Example 1 is shown in the figure. It can be seen from the figure that the fluorescence intensity increases with the increase of the excitation wavelength. When the excitation wavelength increases to 500 nm, the fluorescence intensity reaches the highest value, and the emission wavelength is 560 nm, which is in the range of green light emission.

[0033] Figure 4 The image shows the fluorescence spectrum of the pure state of the bio-based furan-cyclic polysiloxane prepared in Example 2. As can be seen from the image, the fluorescence intensity increases with increasing excitation wavelength. When the excitation wavelength increases to 420 nm, the emission wavelength is 501 nm; and with further increases in excitation wavelength, the emission gradually red-shifts, reaching 562 nm when the excitation wavelength is 520 nm.

[0034] Figure 5The image shows fluorescence images of the bio-based furan-cyclic polysiloxane solution prepared in Example 2. First, polysiloxane solutions of different concentrations were prepared. From left to right in the image, the concentrations increase sequentially: 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 5 mg / mL, 6 mg / mL, 8 mg / mL, 20 mg / mL, 50 mg / mL, and 80 mg / mL. When irradiated with a 254 nm UV lamp, all solutions of different concentrations emitted bright blue fluorescence. Under irradiation with a 365 nm UV lamp, all solutions of different concentrations emitted blue-green fluorescence. When excited with a 410 nm light source, no fluorescence was observed in the dilute solution. When the solution concentration increased to 5 mg / mL, weak green fluorescence was observed, and the intensity of the emitted green fluorescence increased with further increases in concentration.

[0035] Figure 6 The figures show a fluorescence comparison of the bio-based furan-cyclic polysiloxane solutions prepared in Examples 1 (P1), 2 (P2), and 4 (P3). As can be seen from the figures, compared to the polysiloxanes prepared from the flexible monomers 1,4-butanediol (P2) and 2-methyl-1,3-propanediol (P3), specifically when the carbon chain length is shorter and there is no sterically hindered methyl group influence, the emission wavelength of the polymer from 1,3-propanediol (P1) exhibits a significant redshift to 560 nm. This indicates that the shorter flexible carbon chain promotes the formation of unconventional luminescent clusters, enhances spatial interactions, and expands electron delocalization, thereby resulting in the redshift.

Claims

1. A bio-based furan-cyclic polysiloxane fluorescent material, characterized in that, Polysiloxane fluorescent materials were prepared by transesterification polycondensation reaction using different silane coupling agents, bio-based 2,5-furandiethanol and aliphatic diols with different carbon chain lengths. Its structure is as follows: ； or ； Wherein, R1 is one of amino, ethylenediamine, (CH3)2C=N–, or tertiary amine; R2 is one of a straight-chain alkylene group with a carbon chain length of 3-6, -CH2CH(CH3)CH2-, -CH2C(CH3)2CH2-, -CH2CH2NHCH2CH2-, –CH2CH2N(CH3)CH2CH2–, –CH2CH2OCH2CH2–, or 1,4-cyclohexyl; R3 is one of amino, ethylenediamine, or (CH3)2C=N–; n is the degree of polymerization; The preparation method of the bio-based furan-cyclic polysiloxane fluorescent material includes the following steps: Step 1: Mix the silane coupling agent, 2,5-furandiethanol and aliphatic diol in a molar ratio of 1:0.1~1:0.1~1; Step 2: Under nitrogen protection, use an oil bath for heating at a temperature of 90 ℃~110 ℃, and gradually increase the reaction temperature to 110 ℃~180 ℃ in 10 ℃ increments; Step 3: After the reaction is complete, the mixture is cooled to room temperature, ethanol is added to completely dissolve it, and then dialysis is performed for purification. The solvent in the resulting solution is removed by rotary evaporation and then dried in a vacuum oven at 60 °C for 24 h to obtain bio-based furan cyclopolysiloxane fluorescent material.

2. The bio-based furan-cyclic polysiloxane fluorescent material according to claim 1, characterized in that, The aliphatic diols with different carbon chain lengths are one of 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, diethanolamine, N-methyldiethanolamine, diethylene glycol, and 1,4-cyclohexanediol.

3. The bio-based furan-cyclic polysiloxane fluorescent material according to claim 1, characterized in that, The silane coupling agent is one of 3-aminopropyltrimethoxysilane, N,N-dimethyl-3-aminopropyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]propyl-2-imine, γ-aminoethylaminopropyltrimethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, aminopropylmethyldimethoxysilane, and N-(3-(dimethoxysilyl)propyl)propyl-2-imine.

4. A method for preparing a bio-based furan-cyclic polysiloxane fluorescent material according to any one of claims 1 to 3, characterized in that... Includes the following steps: Step 1: Mix the silane coupling agent, 2,5-furandiethanol and aliphatic diol in a molar ratio of 1:0.1~1:0.1~1; Step 2: Under nitrogen protection, use an oil bath for heating at a temperature of 90 ℃~110 ℃, and gradually increase the reaction temperature to 110 ℃~180 ℃ in 10 ℃ increments; Step 3: After the reaction is complete, the mixture is cooled to room temperature, ethanol is added to completely dissolve it, and then dialysis is performed for purification. The solvent in the resulting solution is removed by rotary evaporation and then dried in a vacuum oven at 60 °C for 24 h to obtain bio-based furan cyclopolysiloxane fluorescent material.

5. The method for preparing bio-based furan-cyclic polysiloxane fluorescent material according to claim 4, characterized in that, Methanol, a byproduct generated during the reaction, is gradually removed by increasing the temperature and distilling at atmospheric pressure to drive the polymerization reaction forward and increase the yield.

6. The method for preparing bio-based furan-cyclic polysiloxane fluorescent material according to claim 4, characterized in that, The molar ratio of silane coupling agent, 2,5-furandiethanol and aliphatic diol is 1:0.9:0.

9.

7. The method for preparing bio-based furan-cyclic polysiloxane fluorescent material according to claim 4, characterized in that, The silane coupling agent used is trifunctional, and the prepared bio-based furan-cyclic polysiloxane has a hyperbranched structure; the silane coupling agent used is difunctional, and the prepared bio-based furan-cyclic polysiloxane has a linear structure.

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