Dye-free photocuring composition with tunable fluorescence

Abstract

The invention provides a dye-free photocuring composition with tunable fluorescence. The dye-free photocuring composition is composed of a photoinitiator, a (methyl) acrylate monomer and (methyl) acrylate resin. The composition adopts a specific photoinitiator, does not need to add a fluorescent dye, and has fluorescence emission capability after being cured. The glass transition temperature (Tg) of the cured polymer is controlled by regulating and controlling the types of the (methyl) acrylate monomer and the (methyl) acrylate resin, fluorescence emission of different colors can be achieved, the unique multi-dimensional fluorescence emission characteristic is shown, and the polymer is suitable for the fields of information encryption, anti-counterfeiting and the like.

Description

Technical Field

[0001] The invention belongs to the field of photopolymerization and relates to a photocurable composition that is photoluminescent after polymerization and a preparation method thereof. Background Art

[0002] Photopolymerization is a technology that rapidly solidifies liquid resin into a solid material under the influence of light. This liquid-to-solid transition provides this technology with significant advantages, enabling it to meet a variety of application scenarios and needs.

[0003] However, modern applications are placing increasingly diverse demands on material functionalization. To further expand the application boundaries of photopolymer materials and enable them to better serve cutting-edge fields such as sensing, anti-counterfeiting, and bioimaging, researchers have turned their attention to fluorescence, an important optical phenomenon. As a photophysical process that has attracted much attention in both scientific research and life, fluorescence has shown great potential in many fields due to its unique optical properties. Introducing fluorescence properties into photopolymer systems can give cured materials new optical functions, thereby more accurately meeting the specific needs of different application scenarios.

[0004] Adding phosphors to photopolymerization systems is a common method for achieving fluorescence emission. For example, the patent "A Water-Based LED Photocurable Digital Multi-Anti-Counterfeiting Inkjet and Its Preparation Method" achieves fluorescence emission by adding fluorescent colorants; the patent "A Method for Applying Color-Changing Fluorescent Polymer Hydrogel with Photo-Thermal Orthogonal Control to Temperature Monitoring and Anti-Counterfeiting" achieves photothermal responsive fluorescence emission by adding 7,10-bis(4-(diphenylamino)phenyl)dibenzo[f,h]quinoxaline-2,3-dicarbonitrile and 2,3-bis(2-methylbenzo[b]thiophen-3-yl)-5,6-dihydro-4H-thiophen[2,3-b]thiopyran-4-one, combined with the temperature responsiveness of the polymer. In addition, many studies have also achieved fluorescence emission by adding inorganic fluorescent pigments such as sulfides, rare earth elements, or quantum dots to achieve specific purposes.

[0005] Although the above-mentioned method of adding fluorescent additives can effectively utilize fluorescence emission to realize applications such as anti-counterfeiting, encryption, and information transmission, the introduction of fluorescent dyes not only increases the process steps and costs, but also requires consideration of issues such as system stability in practical applications.

[0006] This invention provides a dye-free photocurable composition with tunable fluorescence. This composition utilizes a specific photoinitiator system, eliminating the need for any fluorescent dyes. By manipulating the (meth)acrylate monomer and (meth)acrylate resin structure to alter the glass transition temperature (Tg) of the photocured product, the composition can achieve fluorescence emission of varying colors. Based on the dual mechanism of monomer selection and phase regulation, this composition exhibits unique multi-dimensional fluorescence tunability. Summary of the Invention

[0007] The object of the present invention is to provide a dye-free photocurable composition with tunable fluorescence.

[0008] A dye-free photocurable composition with tunable fluorescence, characterized in that it is composed of a photoinitiator, a (meth)acrylate monomer and a (meth)acrylate resin, and a compound represented by the structure of general formula (I), (II) or (III) is used as the photoinitiator, wherein the carbon atom at the 2nd position of ring A and the carbon atom at the 8th position of ring B in the general formula (I) are not bonded; the carbon atom at the 2nd position of ring A and the carbon atom at the 8th position of ring B in the general formula (II) are directly connected via a carbon-carbon single bond; the carbon atom at the 2nd position of ring A and the carbon atom at the 8th position of ring B in the general formula (III) are directly connected via a carbon-carbon single bond. The carbon atoms are connected by a —(CH2)n1— group, wherein n1 is 1, 2, 3 or 4; the photoinitiator group is an α-hydroxyacetophenone group or a 1,3-diketone group; in the general formula (I), the photoinitiator group is bonded to the carbon atom at position 2, 3, 4, 5 or 6 of the A ring, or the carbon atom at position 8, 9, 10, 11 or 12 of the B ring; in the general formulas (II) and (III), the photoinitiator group is bonded to the carbon atom at position 3, 4, 5 or 6 of the A ring, or the carbon atom at position 9, 10, 11 or 12 of the B ring;

[0009]

[0010] The structure of R1 in the general formula (I), (II) and (III) is selected from any one of the following structures:

[0011]

[0012] Where n2 = 1, 2, 3 or 4;

[0013] The structures of R2 and R3 in the general formula (I), (II) and (III) are independently selected from any one of the following structures:

[0014] -H-CH3-O-CH3

[0015] The structure of R4 in the general formula (I), (II) and (III) is selected from any one of the following structures:

[0016]

[0017] In R4, X1 is selected from any one of the following structures:

[0018]

[0019] Where n3 = 1, 2, 3 or 4;

[0020] In R4, X2 and X3 are each independently selected from any one of the following structures:

[0021] -H-CH3-OH-O-CH3

[0022] In R4, X4 is selected from any one of the following structures:

[0023] -H-Cl-Br

[0024] In R4, X5 is selected from any one of the following structures:

[0025]

[0026] Wherein n4 is an integer from 1 to 24.

[0027] The photoinitiator is characterized by a double benzene ring structure, with at least one benzene ring containing an α-hydroxyacetophenone or diketone structure capable of initiating monomer polymerization, and the other side having the structure described above. The photoinitiator-containing side ensures the structure possesses photoinitiating ability, enabling the photocurable composition to exhibit fluorescence emission after curing.

[0028] The present invention provides a photocurable composition comprising the aforementioned photoinitiator, characterized in that no fluorescent dye is required, and the glass transition temperature (Tg) of the photocured polymer can be controlled by selecting different (meth)acrylate monomers and (meth)acrylate resin structures to achieve different colors of fluorescent emission. In the curable composition, the molar ratio of the photoinitiator to the (meth)acrylate monomer and (meth)acrylate resin is 0.1-50 mol%, and the functionality of the selected (meth)acrylate monomer and (meth)acrylate resin is monofunctional or difunctional or higher. The (meth)acrylate accounts for 10-100 parts, and the (meth)acrylate resin accounts for 10-100 parts. The (meth)acrylate resin can be selected and matched according to the desired glass transition temperature and intended use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The color of a photocurable composition composed of 1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1-oxoprop-2-yl acrylate, isobornyl acrylate (IBOA) and hydroxyethyl methacrylate (HEA) under visible light and 365nm LED light after photocuring.

[0030] Figure 2 The color of the photocurable composition composed of 1,1'-(methylenebis-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propane], butyl acrylate (BA) and methoxy polyethylene glycol (550) monoacrylate (CD553) after photocuring under visible light and 385nm LED light.

[0031] Figure 3 The color of the photocurable composition of 2-hydroxy-2-methyl-1-(6-methyl-9H-fluoren-3-yl)propan-1-one and polyethylene glycol (200) diacrylate (PEG200DA) after photocuring under visible light and 365nm LED light.

[0032] Figure 4 The color of the photocurable composition of 2-hydroxy-2-methyl-1-(6-methyl-9H-fluoren-3-yl)propan-1-one and polyethylene glycol (400) diacrylate (PEG400DA) after photocuring under visible light and 365nm LED light.

[0033] Figure 5 The color of the photocurable composition of 2-hydroxy-2-methyl-1-(6-methyl-9H-fluoren-3-yl)propan-1-one and polyethylene glycol (600) diacrylate (PEG600DA) after photocuring under visible light and 365nm LED light.

[0034] Figure 6 The color of the photocurable composition of 1,1'-(methylenebis-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propane] and tripropylene glycol diacrylate (TPGDA) after photocuring under visible light and 365nm LED light.

[0035] Figure 7 The color of the photocurable composition of 1,1'-(methylenebis-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propane] and tripropylene glycol diacrylate (TPGDA) after photocuring under visible light and 365nm LED light.

[0036] Figure 8 The color of the photocurable composition of 1,1'-(methylenebis-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propane] and tripropylene glycol diacrylate (TPGDA) after photocuring under visible light and 365nm LED light.

[0037] Figure 9The color of the photocurable composition of 1,1'-(methylenebis-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propane] and tripropylene glycol diacrylate (TPGDA) after photocuring under visible light and 365nm LED light. DETAILED DESCRIPTION

[0038] Example 1

[0039] Specifically, a photoinitiator 1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1-oxoprop-2-yl acrylate (structure shown below) was mixed with isobornyl acrylate (IBOA) and hydroxyethyl methacrylate (HEA) at a molar ratio of IBOA:HEA = 10:1, and the molar proportion of the photoinitiator to the total mass was 1.5 mol%. After the system was cured, it was illuminated under a 365 nm LED lamp (50 mW / cm 2 ) appears orange-red light (see attached Figure 1 ).

[0040] The photoinitiator used in this example has the structural formula:

[0041]

[0042] Example 2

[0043] Specifically, a photoinitiator 1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1-oxoprop-2-yl acrylate was mixed with isobornyl acrylate (IBOA) and butyl acrylate (BA) at a molar ratio of IBOA:BA=9:1, and the molar ratio of the photoinitiator to the total mass was 0.5 mol%. After the system was cured, the system was exposed to a 385 nm LED light (30 mW / cm 2 ) appears as orange-red light under irradiation.

[0044] Example 3

[0045] Specifically, a photoinitiator 1-[4-[4-(2-cyclohexyl-2-hydroxyacetyl)benzyl]phenyl]-2-hydroxy-2-methylpropane-1-one was mixed with glycidyl methacrylate (GMA) and 2-phenoxyethyl acrylate (PEA) at a molar ratio of GMA:PEA=30:1, and the molar ratio of the photoinitiator to the total mass was 2 mol%. After the system was cured, the system was exposed to a 405 nm LED lamp (80 mW / cm 2 ) appears as orange-red light under irradiation.

[0046]

[0047] Example 4

[0048] Specifically, the photoinitiator 1,1'-(methylenebis-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propane] (structure shown below) was mixed with butyl acrylate (BA) and methoxy polyethylene glycol (550) monoacrylate (CD553), wherein the molar ratio of BA:CD553 was 1:1, and the molar proportion of the photoinitiator to the total mass was 1 mol%. After the system was cured, it was illuminated by a 385 nm LED lamp (60 mW / cm 2 ) appears as blue-green light (see attached Figure 2 The photoinitiator used in this example has the structural formula

[0049]

[0050] Example 5

[0051] Specifically, the photoinitiator 2-hydroxy-2-methyl-1-(6-methyl-9H-fluoren-3-yl)propan-1-one (structure shown below) was mixed with polyethylene glycol (200) diacrylate (PEG200DA), polyethylene glycol (400) diacrylate (PEG400DA) and polyethylene glycol (600) diacrylate (PEG600DA), respectively, with the molar ratio of the photoinitiator to the total mass being 2 mol%. After the system was cured, the photoinitiator was illuminated under a 365 nm LED lamp (70 mW / cm 2 ) appears as orange-red light, blue-green light and blue-green light (see attached Figure 3 、 4 and 5).

[0052]

[0053] Example 6

[0054] Specifically, a photoinitiator 1-(9,10-dihydroanthracen-2-yl)-2-hydroxy-2-methylpropan-1-one (structure shown below) was mixed with polyethylene glycol (200) diacrylate (PEG200DA), polyethylene glycol (400) diacrylate (PEG400DA) and ethoxylated trimethylolpropane triacrylate (TMP(EO)3TA), wherein PEG200DA, PEG400DA and TMP(EO)3TA were mixed in a molar ratio of 3:2:1, and the molar ratio of the photoinitiator to the total mass was 0.5 mol%. After the system was cured, a 365 nm LED (50 mW / cm 2 ) It appears orange-red under light.

[0055]

[0056] Example 7

[0057] Specifically, the photoinitiator 1,1'-(methylenebis-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propane] was mixed with polyethylene glycol (200) diacrylate (PEG200DA) and ethoxyethoxy methacrylate (EEEMA), wherein PEG200DA and EEEMA were mixed in a molar ratio of 3:1, and the molar ratio of the photoinitiator to the total mass was 4.5 mol%. After the system was cured, the photoinitiator was heated under a 365 nm LED light (70 mW / cm 2 ) appears as orange-red light under irradiation.

[0058] Example 8

[0059] Specifically, the photoinitiator 4,4'-methylene benzophenone (structure shown below) was mixed with acrylic acid (AA), the molar ratio of the photoinitiator to the monomer was 0.5 mol%, and the co-initiator used diethylene glycol amine as the co-initiator to the monomer molar ratio was 0.3 mol%. After the system was cured, it was illuminated by a 385 nm LED lamp (50 mW / cm 2 ) appears as yellow light under irradiation.

[0060]

[0061] Example 9

[0062] Specifically, the photoinitiator 4-(4-benzoylbenzyloxy)phenyl-2-hydroxy-2-methylpropyl ketone (structure shown below) was mixed with N-(acryloyl)morpholine (ACMO), acrylic acid (AA) and silicone acrylate (CN990), with the molar ratio of the photoinitiator to the total mass being 4 mol%. After the system was cured, the system was illuminated by a 365 nm LED lamp (10 mW / cm 2 ) appears as red light under irradiation.

[0063]

[0064] Example 10

[0065] Specifically, the photoinitiator 4-(4-benzoylbenzyloxy)phenyl-2-hydroxy-2-methylpropyl ketone was mixed with N-(acryloyl)morpholine (ACMO) and N-hydroxyethylacrylamide (HEAA), and the molar ratio of the photoinitiator to the total mass was 2.2 mol%. After the system was cured, the system was exposed to a 365 nm LED lamp (5 mW / cm 2 ) appears as orange-red light under irradiation.

[0066] Example 11

[0067] Specifically, the photoinitiator 4,4'-methylenebis(2-methacryloyloxypropionyl)benzene (structure shown below) was mixed with N-(acryloyl)morpholine (ACMO) and cyclohexyl acrylate (CHA) at a molar ratio of 1.6 mol% of the total mass of the photoinitiator. After the system was cured, the system was exposed to a 365 nm LED lamp (100 mW / cm 2 ) appears as red light under irradiation.

[0068]

[0069] Example 12

[0070] Specifically, a photoinitiator 1-[4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl]prop-2-en-1-one (structure shown below) and cyclohexyl acrylate were mixed with pure acrylic resin (321HT), and the molar ratio of the photoinitiator to the total mass was 2 mol%. After the system was cured, it was illuminated by a 385 nm LED lamp (40 mW / cm 2 ) appears as red light under irradiation.

[0071]

[0072] Example 13

[0073] Specifically, the photoinitiator 1,1'-(methylenebis-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propane] was mixed with tripropylene glycol diacrylate (TPGDA), wherein the molar ratio of the photoinitiator was 3 mol%. After the system was cured, it showed orange light under 365 nm LED light (see attached). Figure 6 ), when the light-cured product is kept at different temperatures, it can be found that the fluorescence emission changes from orange-red light to blue-green light (see Appendix Figure 7 The photocurable composition of this example was filled into a mold and a 365 nm LED light source was turned on for curing. It was observed that the system gradually emitted orange-red fluorescence during the curing process (see attached Figure 8 ), indicating that the fluorescent signal of the composition can evolve regularly along with the polymerization reaction process. Based on this characteristic, the composition of the present invention can realize in-situ, real-time, non-destructive optical monitoring of the photopolymerization reaction, providing a powerful real-time monitoring means for in-depth exploration of the reaction mechanism and optimization of process parameters. The photocurable composition of this example is prepared into the shape of the abbreviation "BUCT" of Beijing University of Chemical Technology and encapsulated in a transparent polymer matrix. Under visible light, the structure is completely transparent; when the 365nm LED lamp (60mW / cm 2 ) when irradiated, the letters “BUCT” showed bright fluorescence (see Appendix Figure 9This phenomenon clearly demonstrates that the photocurable composition of the present invention can be used to embed fluorescent codes that are normally invisible but develop under specific excitation light into complex 3D-printed parts, thereby achieving product traceability and anti-counterfeiting functions.

[0074] Example 14

[0075] Specifically, a photoinitiator, 2-hydroxy-2-methyl-1-[4-(1-phenylethyl)phenyl]propanone (structure shown below), was mixed with 40 parts of isobornyl acrylate (IBOA), 50 parts of bisphenol A epoxy acrylate, 10 parts of polyether acrylate (Photomer5050), and 1 part of a leveling agent. The molar ratio of the photoinitiator to the total mass was 3 mol%. After the system was cured, the light was illuminated by a 365 nm LED lamp (50 mW / cm 2 ) appears as red light under irradiation.

[0076]

[0077] Example 15

[0078] Specifically, the photoinitiator 1-[6-(2-cyclohexyl-2-hydroxyacetyl)-9H-fluoren-3-yl]-2-hydroxy-2-methylpropane-1-one (structure shown below) was mixed with 40 parts of acrylic polyurethane (CN965), 20 parts of polyester acrylate (PEA), 40 parts of amino acrylate (XMA200) and 2 parts of defoamer, with the photoinitiator molar ratio being 2.5 mol%. After the system was cured, the system was illuminated by a 365 nm LED lamp (80 mW / cm 2 ) appears as orange-red light under irradiation.

[0079]

[0080] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent modifications, equivalent replacements or improvements made in accordance with the claims and description of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A dye-free photocurable composition with tunable fluorescence, characterized in that The invention is composed of a photoinitiator, a (meth)acrylate monomer and a (meth)acrylate resin, wherein a compound having a structure represented by general formula (I), (II) or (III) is used as the photoinitiator. In the general formula (I), the carbon atom at the 2nd position of ring A and the carbon atom at the 8th position of ring B are not bonded; in the general formula (II), the carbon atom at the 2nd position of ring A and the carbon atom at the 8th position of ring B are directly connected via a carbon-carbon single bond; in the general formula (III), the carbon atom at the 2nd position of ring A and the carbon atom at the 8th position of ring B are bonded via a -(CH2) bond. n1-group connection, wherein n1 is 1, 2, 3 or 4; the photoinitiator group is an α-hydroxyacetophenone group or a 1,3-diketone group, and in the general formula (I), the photoinitiator group is bonded to the carbon atom at position 2, 3, 4, 5 or 6 of ring A, or the carbon atom at position 8, 9, 10, 11 or 12 of ring B; in the general formulas (II) and (III), the photoinitiator group is bonded to the carbon atom at position 3, 4, 5 or 6 of ring A, or the carbon atom at position 9, 10, 11 or 12 of ring B; The structure of R1 in the general formula (I), (II) and (III) is selected from any one of the following structures: Where n2 = 1, 2, 3 or 4; The structures of R2 and R3 in the general formula (I), (II) and (III) are independently selected from any one of the following structures: -H-CH3-O-CH3 The structure of R4 in the general formula (I), (II) and (III) is selected from any one of the following structures: In R4, X1 is selected from any one of the following structures: -H Where n3 = 1, 2, 3 or 4; In R4, X2 and X3 are each independently selected from any one of the following structures: -H-CH3-OH-O-CH3 In R4, X4 is selected from any one of the following structures: -H-Cl-Br In R4, X5 is selected from any one of the following structures: -CH3 Here, n4 is an integer from 1 to 24.

2. The photocurable composition according to claim 1, characterized in that The (meth)acrylate monomer is selected from alkyl (meth)acrylates, hydroxy (meth)acrylates, (meth)acrylates with a cyclic structure or a benzene ring, alkoxylated alkyl (meth)acrylates or methoxylated alkyl (meth)acrylates; and the (meth)acrylate resin is selected from epoxy (meth)acrylates, polyurethane (meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates, amino (meth)acrylates or silicone (meth)acrylates.

3. The photocurable composition according to claim 1, characterized in that The glass transition temperature (Tg) of the photocured product can be controlled by adjusting the structures of the (meth)acrylate monomer and the (meth)acrylate resin in the photocurable composition, thereby achieving fluorescent emission of different colors of the photocured product.

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