Phosphoryloxy type carbon dot photoinitiator as well as preparation and application thereof

Abstract

The invention relates to a phosphorus acyloxy type carbon dot photoinitiator, the surface of a carbon dot is provided with a group containing a phosphorus acyloxy structure part, and the average particle size of the carbon dot is 1-50nm. The phosphoryloxy type carbon dot photoinitiator as a photoinitiator can show good initiation performance in a range of 200-1200 nm, especially 250-660 nm, and can effectively initiate a photopolymerization reaction of a photopolymerizable monomer, especially a (methyl) acrylate monomer. The invention also relates to a preparation method and application of the phosphoryloxy carbon dot photoinitiator. The phosphoryloxy carbon dot photoinitiator is especially suitable for UV-VIS LED light source curing. The photoinitiator disclosed by the invention is low in biotoxicity, low in migration rate and excellent in biocompatibility, can be applied to the fields of photopolymerization materials, biomacromolecules and the like, and is simple in synthesis route, so that the photoinitiator has extremely high practical value.

Description

Technical Field

[0001] The present invention belongs to the field of photocuring technology, and specifically relates to a phosphoryl oxide-type carbon dot photoinitiator, which is particularly suitable for UV-VIS LED light source curing. The present invention also relates to the preparation and application of the phosphoryl oxide-type carbon dot photoinitiator. Technical Background

[0002] Photoinitiators, also known as photosensitizers or photocuring agents, are substances that absorb energy of a certain wavelength to generate free radicals and cations, thereby initiating polymerization, crosslinking, and curing of monomers. In recent years, photocurable materials have developed rapidly and are widely used in traditional fields such as coatings, inks, microelectronics, and printing, as well as in emerging fields such as the preparation of laser recording and three-dimensional components. Photoinitiators are one of the most important components in photocurable materials. Although their content is low in photocurable systems, they are a key component, determining whether the formulation can rapidly crosslink and cure upon exposure to light, transforming from a liquid to a solid state.

[0003] Currently, the photoinitiators used in industry are essentially small molecules, such as phosphoryl oxide compounds. As free radical photoinitiators, they have become a class of photoinitiators that have gained increasing attention in recent years due to their outstanding activity and excellent photosensitivity. Common commercial products include (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO). In addition, there are also patents regarding phosphoryl oxide photoinitiators, such as CN 113454095A, which discloses a phosphoryl oxide photoinitiator with a phenyl group. Although these photoinitiators have excellent photoinitiating activity, they have some significant drawbacks in terms of residual residue after photocuring, which have not yet been addressed. For example, these photoinitiators are biotoxic. During the photocuring process, residual small molecule photoinitiators easily migrate to the product surface, producing a certain odor. This greatly limits the application of phosphoryl oxide photoinitiators in food packaging, medical and health care, and other aspects.

[0004] In view of this, research and development of phosphoryl oxide photoinitiators with higher environmental performance remains the core work in this field, especially the development of new phosphoryl oxide photoinitiators with low biological toxicity and low mobility that are suitable for the rapidly developing species, which has gradually become the current research direction of phosphoryl oxide photoinitiators. Summary of the Invention

[0005] In view of the problems existing in the prior art, the inventors of the present invention have conducted extensive and in-depth research on phosphoryl oxide photoinitiators with higher environmental performance, in order to find a new phosphoryl oxide photoinitiator with low biological toxicity and low mobility.

[0006] The inventors surprisingly discovered that by taking carbon dots as the basis and regulating the surface groups of the carbon dots, a specific phosphoryloxy structural part is introduced on the surface of the carbon dots in a post-modification manner to form a new type of phosphoryloxy carbon dot photoinitiator, which can be used for UV-VIS LED light source curing. The phosphoryloxy carbon dot photoinitiator of the present invention maintains the morphology of the carbon dots and has a uniform size distribution (1-50nm). It can show good initiation performance in the range of 200-1200nm, especially 250-660nm, and can effectively initiate the photopolymerization reaction of photopolymerizable monomers, especially (meth)acrylate monomers. In addition, the photoinitiator of the present invention has low biological toxicity, low mobility, and excellent biocompatibility. It can be used in the fields of photopolymerizable materials and biomacromolecules, and the synthesis route is simple, thus having extremely high practical value.

[0007] The purpose of the present invention is achieved based on the above findings.

[0008] Therefore, an object of the present invention is to provide a phosphoryl oxide type carbon dot photoinitiator, which not only has an absorption wavelength suitable for UV-VIS LED light source radiation curing, but also has low biological toxicity, low mobility, and excellent biocompatibility.

[0009] Another object of the present invention is to provide a method for preparing the phosphoryl oxide-type carbon dot photoinitiator of the present invention.

[0010] Another object of the present invention is to provide a use of the phosphoryl oxide-type carbon dot photoinitiator of the present invention as a photoinitiator or photosensitizer.

[0011] The technical solutions for achieving the above-mentioned purpose of the present invention can be summarized as follows:

[0012] 1. A phosphoryloxy-type carbon dot photoinitiator, wherein the carbon dot surface has a group containing a phosphoryloxy moiety, and the average particle size of the carbon dot is 1-50 nm.

[0013] 2. The phosphoryloxy carbon dot photoinitiator according to item 1, wherein the average particle size of the carbon dots is 1-20 nm, preferably 1-15 nm, more preferably 1-10 nm.

[0014] 3. The phosphoryloxy carbon point photoinitiator according to item 1 or 2, wherein the group containing the phosphoryloxy structural portion has a structure shown in the following formula (1):

[0015]

[0016] in:

[0017] * indicates the connection position with the carbon dots;

[0018] R1 represents hydrogen, C1-C 20Alkyl, C3-C 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C2-

[0019] C 20 Alkenyl, C3-C 20 Cycloalkenyl, C3-C 10 Cycloalkenyl-C1-C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 Alkyl, wherein the aforementioned C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C2-C 20 Alkenyl, C3-C 20 Cycloalkenyl, C3-C 10 Cycloalkenyl-C1-

[0020] C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 The alkyl group is optionally substituted by one or more groups independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkylthio, C1-C6 alkoxy, halogen, nitro, amino, cyano, mono(C1-C6 alkyl)amino, di(C1-C6 alkyl)amino and mercapto, and the aforementioned C3-C6 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C3-C 20 Cycloalkenyl,

[0021] C3-C 10 Cycloalkenyl-C1-C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 The ring carbon atoms of the alkyl group are optionally replaced by one or more heteroatoms selected from N, S and O.

[0022] 4. The phosphoryloxy carbon dot photoinitiator according to item 3, wherein:

[0023] R1 represents hydrogen, C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-C1-C4 alkyl, C2-C 12 Alkenyl, C3-C 12Cycloalkenyl, C3-C8 cycloalkenyl-C1-C4 alkyl, C6-C 12 Aryl or C6-C 10 Aryl-C1-C4 alkyl, wherein the aforementioned C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-

[0024] C1-C4 alkyl, C2-C 12 Alkenyl, C3-C 12 Cycloalkenyl, C3-C8 cycloalkenyl-C1-C4 alkyl,

[0025] C6-C 12 Aryl or C6-C 10 The aryl-C1-C4 alkyl group is optionally substituted by one or more groups independently selected from the group consisting of C1-C4 alkyl, C1-C4 alkylthio, C1-C4 alkoxy, halogen, nitro, amino, cyano, mono(C1-C4 alkyl)amino, di(C1-C4 alkyl)amino and mercapto, and the aforementioned C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-C1-C4 alkyl, C3-C 12 Cycloalkenyl, C3-C8 cycloalkenyl-

[0026] C1-C4 alkyl, C6-C 12 Aryl or C6-C 10 The ring carbon atoms of the aryl-C1-C4alkyl group are optionally replaced by one or more heteroatoms selected from N, S and O;

[0027] Preferably, R1 represents hydrogen, C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 Cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl, wherein the aforementioned C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 Cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl is optionally substituted by fluorine, chlorine, bromine and C1-C4 alkyl, and the aforementioned C3-C6 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 The ring carbon atoms of the cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl are optionally replaced by one or more heteroatoms selected from N, S and O;

[0028] More preferably, R1 represents hydrogen, C1-C8 alkyl, C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-

[0029] C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-C1-C2 alkyl, phenyl or naphthyl, wherein the aforementioned C1-C8 alkyl, C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-C1-C2 alkyl, phenyl or naphthyl is optionally substituted with C1-C4 alkyl, and the aforementioned C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-

[0030] The ring carbon atoms of the C1-C2 alkyl, phenyl or naphthyl group are optionally replaced by one or more heteroatoms selected from N, S and O.

[0031] 5. The phosphoryloxy carbon dot photoinitiator according to item 3 or 4, wherein R1 represents hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, cyclopropyl, cyclopentylethyl or phenyl, preferably hydrogen, methyl or methoxy.

[0032] 6. A method for preparing the phosphoryloxy carbon dot photoinitiator according to any one of items 1 to 5, comprising the following steps:

[0033] S1: subjecting a compound having at least one aldehyde group and / or hydroxyl group to carbonization under hydrothermal or solvothermal conditions

[0034] The carbon dots with aldehyde groups on the surface were obtained by chemical reaction;

[0035] S2: reacting the carbon dots with aldehyde groups on the surface from step S1 with diphenylphosphine oxide compounds

[0036] Obtaining α-hydroxydiphenylphosphine oxide carbon dots; and

[0037] S3: subjecting the α-hydroxydiphenylphosphine oxide carbon dots from step S2 to oxidation reaction to obtain corresponding phosphoryl oxide-type carbon dot photoinitiators.

[0038] 7. The method according to item 6, wherein the compound having at least one aldehyde group and / or hydroxyl group is selected from compounds having a cyclic structure and having at least one aldehyde group and / or hydroxyl group, and linear compounds having at least 5 carbon atoms and having at least one aldehyde group and / or hydroxyl group, wherein the cyclic structure is optionally substituted with one or more groups independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkylthio, C1-C6 alkoxy and halogen;

[0039] Preferably, the cyclic structure has 5-10 ring members, more preferably 5-8 ring members, for example 5 or 6 ring members, wherein the ring members are C atoms and optionally 1-3 heteroatoms selected from N, O or S, and the cyclic structure is optionally substituted by one or more groups independently selected from the group consisting of C1-C4 alkyl, C1-C4 alkylthio, C1-C4 alkoxy and chlorine.

[0040] 8. The method according to item 6 or 7, wherein the compound having at least one aldehyde group and / or hydroxyl group has 1 to 4, such as 1 or 2, aldehyde groups and / or hydroxyl groups;

[0041] Preferably, the compound having at least one aldehyde group and / or hydroxyl group is of biomass origin, such as furfural, hydroxymethylfurfural, vanillin or cinnamaldehyde.

[0042] 9. The method according to any one of items 6 to 8, wherein the solvent in step S1 is selected from C1-C6 alkyl alcohol, preferably ethanol, N,N-dimethylformamide or dimethyl sulfoxide.

[0043] 10. The method according to any one of items 6 to 9, wherein the mass ratio of the compound having at least one aldehyde group and / or hydroxyl group to water or solvent is 1:1-1:15, preferably 1:2-1:10.

[0044] 11. The method according to any one of items 6 to 10, wherein the carbonization temperature in step S1 is 100-250° C., preferably 120-200° C.; and / or the pressure is 0.1-7 MPa, preferably 0.2-3 MPa; and / or the reaction time is 4-15 h, preferably 6-12 h.

[0045] 12. The method according to any one of items 6 to 11, wherein the reaction of step S2 is carried out in the presence of pyridine, piperidine, triethylamine and / or tetramethylammonium hydroxide, preferably triethylamine, as a catalyst.

[0046] 13. The method according to any one of items 6 to 12, wherein in the reaction of step S2, the mass ratio of the carbon dots having aldehyde groups on the surface to the diphenylphosphine oxide compound is 1:1-1:12, preferably 1:1-1:10.

[0047] 14. The method according to any one of items 6 to 13, wherein the diphenylphosphine oxide compound is a compound of formula (Va):

[0048]

[0049] wherein R1 is as defined in any one of items 3-5.

[0050] 15. The method according to item 14, wherein the diphenylphosphine oxide compound is selected from diphenylphosphine oxide, di(p-tolyl)phosphine oxide, di(p-methoxyphenyl)phosphine oxide, di(3,5-dimethylphenyl)phosphine oxide, phenylmethylphosphine oxide, phenylethylphosphine oxide, phenylisopropylphosphine oxide and phenyl-tert-butylphosphine oxide, preferably diphenylphosphine oxide, di(p-tolyl)phosphine oxide or di(p-methoxyphenyl)phosphine oxide.

[0051] 16. The method according to any one of items 6 to 15, wherein the oxidation reaction in step S3 is carried out in the presence of one or more of manganese dioxide, hydrogen peroxide, Dess-Martin reagent, potassium permanganate, preferably manganese dioxide as an oxidant.

[0052] 17. The method according to item 16, wherein the mass ratio of the α-hydroxydiphenylphosphine oxide carbon dots to the oxidant is 1:1-1:12, preferably 1:1-1:8.

[0053] 18. Use of the phosphoryl oxide type carbon dot photoinitiator obtained according to any one of items 1 to 5 or according to any one of items 6 to 17 as a photoinitiator, especially use as a photoinitiator in a UV-VIS LED light source curing system, especially use as a photoinitiator in a light source curing system with a radiation wavelength of 200-1200 nm, especially 250-660 nm.

[0054] 19. A photocurable composition comprising at least one phosphoryl oxide type carbon dot photoinitiator obtained according to any one of items 1 to 5 or according to any one of items 6 to 17.

[0055] 20. A cured material obtainable from the photocurable composition according to item 19.

[0056] 21. A method for preparing a photocurable material, comprising the step of irradiating the photocurable composition according to item 19 with a light source having a radiation wavelength of 200-1200 nm, especially 250-660 nm, such as a UV-VIS LED light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 TEM images of carbon dots (CDs), α-hydroxydiphenylphosphine oxide carbon dots (A), and phosphoryl oxide carbon dots (CD-PI) obtained in steps S1 / S2 / S3 in Example 1 of the present invention;

[0058] Figure 2 1 is the XRD spectra of the carbon dots (CDs), α-hydroxydiphenylphosphine oxide carbon dots (A), and phosphoryl oxide carbon dots (CD-PI) obtained in steps S1 / S2 / S3 in Example 1 of the present invention;

[0059] Figure 3 are UV-visible absorption spectra of carbon dots (CDs), α-hydroxydiphenylphosphine oxide carbon dots (A), and phosphoryl oxide carbon dots (CD-PI) obtained in steps S1 / S2 / S3 in Example 1 of the present invention;

[0060] Figure 4 IR absorption spectra of carbon dots (CDs), α-hydroxydiphenylphosphine oxide carbon dots (A), and phosphoryl oxide carbon dots (CD-PI) obtained in steps S1 / S2 / S3 of Example 1 of the present invention;

[0061] Figure 5 The photopolymerized film is obtained by polymerizing diurethane dimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA) by initiating polymerization of the phosphoryl oxide carbon dots (CD-PI) obtained in Example 1 of the present invention under a 365 nm LED light source;

[0062] Figure 6 This is a comparative mobility test graph of the phosphoryl oxide carbon dots (CD-PI) obtained in Example 1 of the present invention and commercial TPO;

[0063] Figure 7 3 is a graph showing the cell viability of the phosphoryl oxide carbon dots (CD-PI) obtained in Example 1 of the present invention compared with commercial TPO. DETAILED DESCRIPTION

[0064] According to a first aspect of the present invention, a phosphoryloxy-type carbon dot photoinitiator is provided, wherein the carbon dots have groups containing phosphoryloxy structural moieties on their surfaces, and the average particle size of the carbon dots is 1-50 nm.

[0065] In one embodiment of the present invention, the average particle size of the carbon dots is 1-20 nm, preferably 1-15 nm, and more preferably 1-10 nm.

[0066] In a particularly preferred embodiment of the present invention, the average particle size of the carbon dots is 1-5 nm.

[0067] In one embodiment of the present invention, the group containing the phosphoryloxy moiety has the structure shown in the following formula (1):

[0068]

[0069] in:

[0070] * indicates the connection position with the carbon dots;

[0071] R1 represents hydrogen, C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C2-

[0072] C 20 Alkenyl, C3-C 20 Cycloalkenyl, C3-C 10 Cycloalkenyl-C1-C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 Alkyl, wherein the aforementioned C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C2-C 20 Alkenyl, C3-C 20 Cycloalkenyl, C3-C 10 Cycloalkenyl-C1-

[0073] C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 The alkyl group is optionally substituted by one or more groups independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkylthio, C1-C6 alkoxy, halogen, nitro, amino, cyano, mono(C1-C6 alkyl)amino, di(C1-C6 alkyl)amino and mercapto, and the aforementioned C3-C6 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C3-C 20 Cycloalkenyl,

[0074] C3-C 10 Cycloalkenyl-C1-C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 The ring carbon atoms of the alkyl group are optionally replaced by one or more heteroatoms selected from N, S and O.

[0075] In the present invention, the prefix "C n -C m " in each case means that the number of carbon atoms contained in the group is nm.

[0076] "Halogen" refers to fluorine, chlorine, bromine and iodine. In the present invention, it is preferred that halogen is fluorine, chlorine, bromine or a combination thereof.

[0077] The term "C n -C m"Alkyl" means a branched or unbranched saturated hydrocarbon radical having nm, for example 1 to 20, carbon atoms, for example methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylbutyl, 2,2-dimethylpropyl -methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl and its isomers, etc.

[0078] The term "C6-C m The term "aryl" refers to a monocyclic or bicyclic aromatic hydrocarbon group containing 6 to m carbon atoms, such as 6 to 20 carbon atoms, for example, phenyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, xylyl, methylethylphenyl, diethylphenyl, methylpropylphenyl, naphthyl and isomers thereof.

[0079] The term "C2-C m "Alkenyl" refers to a branched or unbranched unsaturated hydrocarbon group having 2 to 20 carbon atoms, for example, 2 to 20 carbon atoms, and having one double bond located at any position, for example, ethenyl, 1-propenyl, 2-propenyl, 1-methylethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl and isomers thereof.

[0080] The term "C3-C m The term "cycloalkyl" refers to a saturated alicyclic monocyclic group having 3 to 20 ring carbon atoms, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl and isomers thereof.

[0081] The term "C3-C m The term "cycloalkenyl" refers to an unsaturated alicyclic monocyclic group having 3 to 20 ring carbon atoms, for example, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, cyclodecenyl and isomers thereof.

[0082] The term "C3-C m Cycloalkyl-C n -C m "Alkyl" means C3-Cm Cycloalkyl substituted C n -C m Alkyl, in which case the two m's may be the same or different, wherein C n -C m Alkyl and C3-C m The definition of cycloalkyl herein applies. For example, C3-C m Cycloalkyl-C n -C m The alkyl group can be a C3-C6 cycloalkyl-C1-C4 alkyl group, such as cyclopropylmethyl, cyclopropylethyl, cyclopropylpropyl, cyclopropylbutyl, cyclobutylmethyl, cyclobutylethyl, cyclobutylpropyl, cyclobutylbutyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylpropyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylpropyl, cyclohexylbutyl and isomers thereof.

[0083] The term "C3-C m Cycloalkenyl-C n -C m "Alkyl" means C3-C m Cycloalkenyl-substituted C n -C m Alkyl, in which case the two m's may be the same or different, wherein C n -C m Alkyl and C3-C m The definition of cycloalkenyl herein applies. For example, C3-C m Cycloalkenyl-C n -C m The alkyl group can be a C3-C6 cycloalkenyl-C1-C4 alkyl group, such as cyclopropenylmethyl, cyclopropenylethyl, cyclopropenylpropyl, cyclopropenylbutyl, cyclobutenylmethyl, cyclobutenylethyl, cyclobutenylpropyl, cyclobutenylbutyl, cyclopentenylmethyl, cyclopentenylethyl, cyclopentenylpropyl, cyclopentenylbutyl, cyclohexenylmethyl, cyclohexenylethyl, cyclohexenylpropyl, cyclohexenylbutyl and isomers thereof.

[0084] The term "C6-C m Aryl-C n -C m "Alkyl" means C6-C m Aryl-substituted C n -C m Alkyl, in which case the two m's may be the same or different, wherein C n -C m Alkyl and C6-C m The definition of aryl herein applies. m Aryl-C n -C m The alkyl group can be C6-C 10Aryl-C1-C4 alkyl, such as benzyl, phenethyl, naphthylmethyl, naphthylethyl, etc.

[0085] The term "C n -C m "Alkoxy (thio) group" includes "C n -C m Alkoxy" and "C n -C m "Alkylthio" refers to a C n -C m Alkyl corresponding open chain C n -C m Any carbon atom of an alkane is bonded with an oxygen atom or a sulfur atom as a linking group. n -C m Alkyl groups such as C1-C6 alkoxy(thio) groups, for example, C1-C6 alkoxy groups such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, 2-butoxy, tert-butoxy, pentyloxy, isopentyloxy, hexyloxy and isomers thereof, and C1-C6 alkylthio groups such as methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, 2-butylthio, tert-butylthio, pentylthio, isopentylthio, hexylthio and isomers thereof, etc.

[0086] In one embodiment of the present invention, R1 represents hydrogen, C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-C1-C4 alkyl, C2-C 12 Alkenyl, C3-C 12 Cycloalkenyl, C3-C8 cycloalkenyl-C1-C4 alkyl, C6-C 12 Aryl or C6-C 10 Aryl-C1-C4 alkyl, wherein the aforementioned C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-C1-C4 alkyl, C2-C 12 Alkenyl, C3-C 12 Cycloalkenyl, C3-C8 cycloalkenyl-C1-C4 alkyl, C6-C 12 Aryl or C6-C 10 The aryl-C1-C4 alkyl group is optionally substituted by one or more groups independently selected from the group consisting of C1-C4 alkyl, C1-C4 alkylthio, C1-C4 alkoxy, halogen, nitro, amino, cyano, mono(C1-C4 alkyl)amino, di(C1-C4 alkyl)amino and mercapto, and the aforementioned C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-C1-C4 alkyl, C3-C 12 Cycloalkenyl, C3-C8 cycloalkenyl-C1-C4 alkyl, C6-C 12Aryl or C6-C 10 The ring carbon atoms of the aryl-C1-C4alkyl group are optionally replaced by one or more heteroatoms selected from N, S and O.

[0087] In a preferred embodiment of the present invention, R1 represents hydrogen, C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 Cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl, wherein the aforementioned C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 Cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl is optionally substituted by fluorine, chlorine, bromine and C1-C4 alkyl, and the aforementioned C3-C6 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 The ring carbon atoms of the cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl are optionally replaced by one or more heteroatoms selected from N, S and O.

[0088] In a more preferred embodiment of the present invention, R1 represents hydrogen, C1-C8 alkyl, C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-C1-C2 alkyl, phenyl or naphthyl, wherein the aforementioned C1-C8 alkyl, C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-C1-C2 alkyl, phenyl or naphthyl is optionally substituted by C1-C4 alkyl, and the ring carbon atoms of the aforementioned C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-C1-C2 alkyl, phenyl or naphthyl are optionally replaced by one or more heteroatoms selected from N, S and O.

[0089] In a particularly preferred embodiment of the present invention, R1 represents hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, cyclopropyl, cyclopentylethyl or phenyl, preferably hydrogen, methyl or methoxy.

[0090] In some particularly preferred embodiments of the present invention, the phosphoryloxy carbon point photoinitiator of the present invention has a structure shown in the following formula (I)-(III):

[0091]

[0092] According to a second aspect of the present invention, there is provided a method for preparing the phosphoryl oxide-type carbon dot photoinitiator of the present invention, comprising the following steps:

[0093] S1: subjecting a compound having at least one aldehyde group and / or hydroxyl group to carbonization under hydrothermal or solvothermal conditions

[0094] The carbon dots with aldehyde groups on the surface were obtained by chemical reaction;

[0095] S2: reacting the carbon dots with aldehyde groups on the surface from step S1 with diphenylphosphine oxide compounds

[0096] Obtaining α-hydroxydiphenylphosphine oxide carbon dots; and

[0097] S3: subjecting the α-hydroxydiphenylphosphine oxide carbon dots from step S2 to oxidation reaction to obtain corresponding phosphoryl oxide-type carbon dot photoinitiators.

[0098] In order to prepare the phosphoryl oxide type carbon dot photoinitiator of the present invention, it is necessary to start from a specific compound having at least one aldehyde group and / or hydroxyl group, first perform a carbonization reaction to obtain carbon dots with aldehyde groups on the surface, then react with diphenylphosphine oxide compounds to obtain α-hydroxydiphenylphosphine oxide carbon dots, and then convert the hydroxyl group into the corresponding carbonyl group through an oxidation reaction, thereby obtaining the phosphoryl oxide type carbon dot photoinitiator of the present invention.

[0099] carbonization reaction

[0100] In the carbonization reaction of step S1 , a specific compound having at least one aldehyde group and / or hydroxyl group is subjected to a carbonization reaction under hydrothermal or solvothermal conditions to obtain carbon dots having aldehyde groups on their surfaces.

[0101] In the carbonization reaction, the compound having at least one aldehyde group and / or hydroxyl group that can be used is selected from a compound having a cyclic structure and having at least one aldehyde group and / or hydroxyl group and a linear compound having at least 5 carbon atoms and having at least one aldehyde group and / or hydroxyl group, wherein the cyclic structure is optionally substituted by one or more groups independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkylthio, C1-C6 alkoxy and halogen.

[0102] In one embodiment of the present invention, the cyclic structure of the compound having at least one aldehyde group and / or hydroxyl group has 5-10 ring members, more preferably 5-8 ring members, for example 5 or 6 ring members, wherein the ring members are C atoms and optionally 1-3 heteroatoms selected from N, O or S, and the cyclic structure is optionally substituted by one or more groups independently selected from the following groups: C1-C4 alkyl, C1-C4 alkylthio, C1-C4 alkoxy and chlorine.

[0103] In a preferred embodiment of the present invention, the compound having at least one aldehyde group and / or hydroxyl group has 1 to 4, such as 1 or 2, aldehyde groups and / or hydroxyl groups.

[0104] In a more preferred embodiment of the present invention, the compound having at least one aldehyde group and / or hydroxyl group is of biomass origin, such as furfural, hydroxymethylfurfural, vanillin or cinnamaldehyde.

[0105] In order to accelerate the carbonization reaction, the above reaction is usually carried out under hydrothermal or solvent thermal conditions. As the solvent, C1-C6 alkyl alcohol, preferably ethanol, N,N-dimethylformamide or dimethyl sulfoxide can be used.

[0106] In the carbonization reaction of step S1 , the mass ratio of the compound having at least one aldehyde group and / or hydroxyl group to water or solvent may be 1:1-1:15, preferably 1:2-1:10.

[0107] The temperature range of the carbonization reaction may be 100-250° C., preferably 120-200° C.; the pressure may be 0.1-7 MPa, preferably 0.2-3 MPa; and the reaction time may be 4-15 hours, preferably 6-12 hours.

[0108] After the carbonization reaction in step S1 is completed, the reaction system can be naturally cooled to room temperature before removing the precipitate. There is no particular limitation on the means for removing the precipitate, and it can usually be removed by centrifugation. After removing the precipitate, a supernatant is obtained. The supernatant is dialyzed through a dialysis bag of specific specifications, such as a dialysis bag with a molecular weight cutoff of 300 Da for 1-3 days, preferably 2 days, to obtain a carbon dot solution containing aldehyde groups on the surface. The aldehyde content in the obtained carbon dot solution is measured by potentiometric titration, and the measurement result is about 7.5 mmol / g-200 mmol / g, preferably 10 mmol / g-100 mmol / g.

[0109] Reaction of step S2

[0110] In the reaction of step S2, the carbon dots having aldehyde groups on the surface obtained in step S1 react with a diphenylphosphine oxide compound to obtain α-hydroxydiphenylphosphine oxide carbon dots.

[0111] The reaction of step S2 can be carried out in the presence of pyridine, piperidine, triethylamine and / or tetramethylammonium hydroxide, preferably triethylamine as a catalyst. The amount of catalyst used is conventional and can be determined by common sense in the art, or by several routine preliminary experiments.

[0112] The reaction in step S2 can be carried out in one or more of tetrahydrofuran, ethyl acetate, dichloromethane, acetone, 1,2-dichloroethane, and cyclohexane, preferably tetrahydrofuran. The amount of solvent used is conventional and can be determined by common sense in the art or by several routine preliminary experiments.

[0113] In the reaction of step S2, the mass ratio of the carbon dots having aldehyde groups on the surface to the diphenylphosphine oxide compound can be 1:1-1:12, preferably 1:1-1:10.

[0114] In the reaction of step S2, the reaction temperature may be in the range of 10-50°C, preferably 20-40°C; and the reaction time may be in the range of 8-48 hours, preferably 18-28 hours.

[0115] The diphenylphosphine oxide compound used in step S2 can be a compound of formula (Va):

[0116]

[0117] wherein R1 is as defined above.

[0118] The diphenylphosphine oxide compound can be selected from diphenylphosphine oxide, di(p-tolyl)phosphine oxide, di(p-methoxyphenyl)phosphine oxide, di(3,5-dimethylphenyl)phosphine oxide, phenylmethylphosphine oxide, phenylethylphosphine oxide, phenylisopropylphosphine oxide and phenyl-tert-butylphosphine oxide, preferably diphenylphosphine oxide, di(p-tolyl)phosphine oxide or di(p-methoxyphenyl)phosphine oxide.

[0119] After the reaction in step S2 is completed, post-processing can be performed according to conventional operations in the art. For example, the reaction system can be filtered and the precipitate can be collected. The precipitate can be washed with the above-mentioned solvent, then filtered and dried conventionally.

[0120] Oxidation reaction in step S3

[0121] In the oxidation reaction of step S3, the α-hydroxydiphenylphosphine oxide carbon dots from step S2 are oxidized to obtain the corresponding phosphoryl oxide type carbon dot photoinitiator.

[0122] According to the present invention, the oxidation reaction in step S3 is performed by reacting the α-hydroxydiphenylphosphine oxide carbon dots obtained in step S2 with an oxidant. This oxidation reaction is routine for those skilled in the art, and the oxidant is not particularly limited, as long as it can convert the hydroxyl group in the α-hydroxydiphenylphosphine oxide carbon dots obtained in step S2 into a carbonyl group. For example, one or more of manganese dioxide, hydrogen peroxide, Dess-Martin reagent, and potassium permanganate can be used, with manganese dioxide being preferred.

[0123] The above oxidation reaction is usually carried out in a solvent, preferably an organic solvent. Examples of solvents include one or more of dichloromethane, ethyl acetate, tetrahydrofuran, acetone, 1,2-dichloroethane, methyl acetate, and chlorobenzene, preferably tetrahydrofuran. The amount of solvent used is conventional and can be determined by common sense in the art or by a few routine preliminary experiments.

[0124] In the oxidation reaction of step S3, the mass ratio of α-hydroxydiphenylphosphine oxide carbon dots to the oxidant can be 1:1-1:12, preferably 1:1-1:8.

[0125] The temperature range of the above oxidation reaction is usually 10-50° C., preferably 20-40° C. The oxidation reaction time is also not particularly limited, and is usually carried out for 8-48 hours, preferably 12-28 hours.

[0126] After the oxidation reaction is complete, the reaction system can be post-treated to obtain the purified phosphoryloxy carbon dot photoinitiator of the present invention. Advantageously, according to the present invention, the reaction mixture obtained by the oxidation reaction is subjected to a diatomaceous earth column to remove the oxidant from the system, and the solvent is removed by rotary evaporation, followed by conventional drying.

[0127] The phosphoryl oxide-based carbon dot photoinitiator of the present invention can be used for UV-VIS LED light source curing. It exhibits excellent initiation performance in the wavelength range of 200-1200 nm, particularly 250-660 nm, and can effectively initiate the photopolymerization of photopolymerizable monomers, especially (meth)acrylate monomers. Furthermore, the photoinitiator of the present invention has low biotoxicity, low mobility, and excellent biocompatibility, making it suitable for applications in photopolymerizable materials and biomacromolecules. Its simple synthesis route also makes it highly practical.

[0128] Therefore, according to the third aspect of the present invention, there is provided the use of the phosphoryl oxide type carbon dot photoinitiator of the present invention. The phosphoryl oxide type carbon dot photoinitiator of the present invention can be applied to UV-VIS LED photocuring technology and can effectively initiate the curing reaction. It is particularly preferred that the phosphoryl oxide type carbon dot photoinitiator of the present invention is used as a photoinitiator in a photocuring system with a radiation wavelength of 200-1200nm, especially 250-660nm. The phosphoryl oxide type carbon dot photoinitiator of the present invention can also be used as a photoinitiator or photosensitizer in the fields of coatings, inks, microelectronics, printing, etc. When the phosphoryl oxide type carbon dot photoinitiator of the present invention is used as a photoinitiator, its dosage is conventional, or can be determined by routine preliminary tests.

[0129] According to a fourth aspect of the present invention, there is provided a photocurable composition comprising the phosphoryl oxide-type carbon dot photoinitiator of the present invention.

[0130] In the photocurable composition, the amount of the photoinitiator of the present invention is generally 0.01 to 10% by weight, preferably 0.1 to 6% by weight, such as 0.2 to 5% by weight, based on the amount of active ingredients of the photocurable composition.

[0131] In the context of this disclosure, active ingredients refer to the ingredients in the photocurable composition other than the solvent.

[0132] In addition to the photoinitiator of the present invention, the photocurable composition further comprises a photocurable resin.

[0133] In the present invention, a photocurable resin refers to an oligomer or prepolymer containing unsaturated carbon-carbon double bonds. Upon exposure to light, this oligomer or prepolymer undergoes a polymerization reaction initiated by a photoinitiator, leading to crosslinking and curing. Photocurable resins are the main component of photocurable products (e.g., UV coatings, UV inks, and UV adhesives).

[0134] As the photocurable resin, there may be mentioned epoxy (meth)acrylate resins, polyester (meth)acrylates, polyurethane (meth)acrylates, ethylenically unsaturated polyesters, amino (meth)acrylate resins, photoimageable alkali-soluble resins, etc. According to the present invention, it is advantageous to use epoxy (meth)acrylate resins, polyester (meth)acrylates, polyurethane (meth)acrylates, or combinations thereof.

[0135] The epoxy (meth)acrylate resin is preferably bisphenol A epoxy (meth)acrylate, bisphenol A epoxy acrylate diluted with tripropylene glycol di(meth)acrylate, or a combination thereof, such as bisphenol A epoxy acrylate WSR-U125 from Wuxi Resin Factory, modified bisphenol A epoxy acrylate 623-100 from Taiwan Changxing Chemical Company, modified bisphenol A epoxy acrylate 6231A-80 diluted with 20% tripropylene glycol diacrylate from Taiwan Changxing Chemical Company, etc.

[0136] The polyester (meth)acrylate is preferably a high-functionality hyperbranched polyester acrylate resin, particularly a hyperbranched polyester acrylate resin with a functionality of 5-30, such as a hyperbranched polyester acrylate prepolymer with a functionality of 6-20. Examples of such prepolymers include hyperbranched polyester acrylate prepolymer 932-100 (6 functionality) from Wuxi Knox Co., Ltd., and hyperbranched polyester acrylate prepolymers CN2300 (8 functionality), CN2301 (9 functionality), and CN2302 (16 functionality) from Sartomer Co., Ltd., USA.

[0137] The polyurethane (meth)acrylate is preferably an aliphatic polyurethane acrylate resin. Examples of the polyurethane (meth)acrylate include aliphatic polyurethane acrylate CN9013 (9-functionality) from Sartomer, Inc., USA; aliphatic polyurethane acrylate CN966B85 (2-functionality) diluted with 15% 1,6-hexanediol diacrylate (HDDA) from Sartomer, Inc., USA; and aliphatic polyurethane acrylate CN962 (2-functionality).

[0138] The photocurable resin is generally used in the photocurable composition in an amount of 10 to 90% by weight, preferably 55 to 80% by weight, based on the amount of active ingredients in the photocurable composition.

[0139] The photocurable composition may further include a multifunctional reactive diluent.

[0140] In the present invention, a multifunctional reactive diluent refers to a monomer containing two or more photopolymerizable groups. Multifunctional reactive diluents have low viscosity and strong dissolving power. Upon exposure to a light source, multifunctional reactive diluents can be polymerized by reactive free radicals to form a crosslinked network.

[0141] According to the present invention, the preferred multifunctional reactive diluent is a multifunctional (meth)acrylate reactive diluent. This refers to a monomer containing two or more (meth)acrylate polymerizable groups. Examples of multifunctional (meth)acrylate reactive diluents include trimethylolpropane triacrylate (TMPTA), propoxylated trimethylolpropane triacrylate (PO-TMPTA), ethoxylated trimethylolpropane triacrylate (EO-TMPTA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPEPA), dipentaerythritol hexaacrylate (DPHA), tripropylene glycol diacrylate (TPGDA), 1,6-hexanediol diacrylate (HDDA), triethylene glycol dimethacrylate (TEGDMA), diethylene glycol dimethacrylate (DEGDMA), glycerol diacrylate, and diurethane dimethacrylate (UDMA).

[0142] The amount of the multifunctional reactive diluent used in the photocurable composition is generally 8 to 60% by weight, preferably 15 to 45% by weight, based on the amount of the active ingredients in the photocurable composition.

[0143] According to the present invention, the photocurable composition may further comprise a monofunctional reactive diluent.

[0144] In the present invention, a monofunctional reactive diluent refers to a monomer containing a photopolymerizable group. It has a low viscosity and a strong dissolving power, and can act as a partial organic solvent. After being irradiated by a light source, the monofunctional reactive diluent can be initiated to undergo polymerization by active free radicals. Monofunctional reactive diluents mainly include (meth)acrylate compounds and vinyl compounds. As (meth)acrylate monofunctional reactive diluents, methyl methacrylate (MMA), n-butyl acrylate (BA), isooctyl acrylate (2-EHA), isodecyl acrylate (IDA), lauryl acrylate (LA), hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and some (meth)acrylates with cyclic structures can be mentioned. In addition, as vinyl monofunctional reactive diluents, styrene (St), vinyl acetate (VA), N-vinyl pyrrolidone (NVP), etc. can be mentioned.

[0145] The monofunctional reactive diluent is generally used in the photocurable composition in an amount of 5 to 50% by weight, preferably 8 to 40% by weight, based on the amount of the active ingredients in the photocurable composition.

[0146] The photocurable composition of the present invention may also optionally contain an organic solvent. The selection of the organic solvent is conventional. As the organic solvent, aromatic hydrocarbons such as benzene and toluene, halogenated alkanes such as chloroform, dichloromethane, and ethyl chloride, ketones such as acetone, butanone, and pentanone, and alcohols such as methanol, ethanol, propanol, isopropanol, and ethylene glycol, and glycol ethers, glycol ether acetates, propylene glycol ethers, and propylene glycol ether acetates can be mentioned. The amount of the organic solvent used is conventional and can be determined by common sense in the art or by several routine preliminary experiments.

[0147] The photocurable composition of the present invention may also optionally contain other additives, such as leveling agents, antioxidants, anti-settling agents, colorants, microbicides, such as antibacterial agents and thermal insulation additives. In a preferred embodiment of the present invention, the leveling agent is selected from the group consisting of FLOW series leveling agents, particularly preferably 360S, 372S, 384S, 392S, 400U, 415U, etc. The amount of the additive is conventional and can be determined by common sense in the art or by a few routine preliminary experiments.

[0148] The preparation of the photocurable composition of the present invention is conventional, for example, the various components of the photocurable composition of the present invention are uniformly mixed together.

[0149] According to a fifth aspect of the present invention, a cured material obtainable from the photocurable composition of the present invention is provided. The resulting cured material can be a photocurable coating, including coatings containing functional materials, UV and / or visible light filter coatings; sealants; photolithographic materials; holographic recording materials; 3D printing materials; lithographic materials; materials for preparing optical devices; and materials for improving mechanical properties, such as carbon fiber composites and / or inorganic and / or organic nanoparticles.

[0150] According to a sixth aspect of the present invention, a method for preparing a photocurable material is provided, comprising the steps of irradiating the photocurable composition of the present invention with a light source having a radiation wavelength of 200-1200 nm, especially 250-660 nm, such as a UV-VIS LED light source.

[0151] The phosphoryloxy carbon dot photoinitiator disclosed in this invention has a simple synthetic route and is well-suited for industrial production. This photoinitiator exhibits excellent compatibility with UV-VIS LED light sources with a radiation wavelength of 200-1200 nm, particularly 250-660 nm. It can be widely used in applications related to UV-VIS LED photocuring, including traditional applications such as coatings, inks, microelectronics, and printing, as well as emerging applications such as the preparation of laser recording and three-dimensional components. Therefore, the phosphoryloxy carbon dot photoinitiator of this invention has promising market prospects.

[0152] In particular, given the shortcomings of phosphoryl oxide photoinitiators currently available for UV-VIS LED light source curing in terms of biotoxicity caused by photocuring residues, the phosphoryl oxide-based carbon dot photoinitiator of the present invention has low biotoxicity and low mobility, as well as excellent biocompatibility and a simple synthesis route, and can make substantial contributions to promoting the application of green and environmentally friendly UV curing industry.

[0153] Example

[0154] The scheme of the present invention will be explained below with reference to the examples. Those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are followed.

[0155] Example 1:

[0156] Preparation of Phosphoryl Oxygen-Based Carbon Dot Photoinitiator

[0157] Step S1: Synthesis of biomass-based aldehyde-containing carbon dots

[0158] To a 100-mL polytetrafluoroethylene-lined reactor, 2.5 mL of the biomass raw material furfural was added, followed by 25 mL of anhydrous ethanol. After thorough mixing and dissolution, the reactor was covered and placed in an oven at 180°C for 8 hours at autogenous pressure. After the reaction was completed and allowed to cool to room temperature, the lid was opened to obtain a black reaction solution. After centrifugation to remove the precipitate, the supernatant was dialyzed for two days using a 300 Da molecular weight cutoff dialysis bag to obtain 27 mL of a 10 mg / mL solution of black carbon dots (CDs) containing aldehyde groups on their surfaces. The aldehyde content of the resulting CD solution was determined by potentiometric titration and found to be 100 mmol / g. The solution was then analyzed using TEM, XRD, UV-visible, and IR spectra (see below for details).

[0159] Step S2: Synthesis of α-hydroxydiphenylphosphine oxide carbon dots

[0160] To a 250 mL reaction flask, add 6 g of diphenylphosphine oxide and dissolve thoroughly in 20 mL of dry tetrahydrofuran. Then, add 65 mL of the above carbon dot solution and mix thoroughly. While stirring, add 1.5 mL of triethylamine dropwise. The mixture is allowed to react at room temperature for 24 hours. After the reaction is complete, filter and collect the precipitate. The precipitate is then washed three times with dry tetrahydrofuran, filtered to remove any unreacted material, and collected. After drying, the precipitate yields 3.5 g of brown α-hydroxydiphenylphosphine oxide carbon dots.

[0161] Step S3: Synthesis of phosphoryloxy carbon dots

[0162] To a 100 mL reaction flask, 0.5 g of the aforementioned α-hydroxydiphenylphosphine oxide carbon dots were added and thoroughly dissolved in 20 mL of anhydrous dichloromethane. Then, 2 g of manganese dioxide was added, and the reaction was allowed to proceed at room temperature under a nitrogen atmosphere for 18 hours. After the reaction, the manganese dioxide was removed using a celite column. The anhydrous dichloromethane was removed by rotary evaporation at 35°C and -0.1 MPa, and the mixture was dried to yield 0.6 g of light yellow phosphoryl oxide carbon dots. Their structure and properties are described below.

[0163] Example 2

[0164] The method of Example 1 was repeated, except that the biomass raw material in step S1 was hydroxymethylfurfural.

[0165] Example 3

[0166] The method of Example 1 was repeated, except that the biomass raw material in step S1 was cinnamaldehyde.

[0167] Example 4

[0168] The method of Example 1 was repeated, except that the biomass raw material in step S1 was vanillin.

[0169] Example 5

[0170] The method of Example 1 was repeated, except that the diphenylphosphine oxide in step S2 was replaced by di(p-methylphenyl)phosphine oxide.

[0171] Example 6

[0172] The method of Example 1 was repeated, except that the diphenylphosphine oxide in step S2 was replaced by p-bis(p-methoxyphenyl)phosphine oxide.

[0173] Analysis and results of the carbon dots, α-hydroxydiphenylphosphine oxide carbon dots, and phosphoryl oxide carbon dots prepared in steps S1, S2, and S3 of Example 1:

[0174] The carbon dots, α-hydroxydiphenylphosphine oxide carbon dots and phosphoryl oxide carbon dots prepared in steps S1, S2 and S3 of Example 1 were analyzed by transmission electron microscopy, and the transmission electron microscopy images are shown in FIG. Figure 1 The results showed that the carbon dots, α-hydroxydiphenylphosphine oxide carbon dots and phosphoryl oxide carbon dots prepared in steps S1, S2 and S3 all had a carbon dot particle structure, and the particle size of the carbon dots was 1-10 nm.

[0175] XRD analysis was performed on the carbon dots, α-hydroxydiphenylphosphine oxide carbon dots and phosphoryl oxide carbon dots prepared in steps S1, S2 and S3 of Example 1, respectively. The XRD results are shown in FIG. Figure 2 The results show that the carbon dots exhibit a peak at around 20°, indicating an amorphous structure. The particle structure remains unchanged after surface modification, indicating that surface modification does not destroy the carbon dot structure.

[0176] The carbon dots, α-hydroxydiphenylphosphine oxide carbon dots and phosphoryl oxide carbon dots prepared in steps S1, S2 and S3 of Example 1 were measured for UV-visible absorption by a UV-visible spectrophotometer in the wavelength range of 220-500 nm. The UV-visible absorption spectra were as follows: Figure 3 The results show that compared with the absorption spectrum of carbon dots, the absorption spectrum of phosphoryl oxide carbon dots after surface modification shows an obvious blue shift, with the main absorption band being 250-350nm.

[0177] Furthermore, the changes in the functional groups of the carbon dots, α-hydroxydiphenylphosphine oxide carbon dots and phosphoryl oxide carbon dots prepared in steps S1, S2 and S3 of Example 1 were analyzed by Fourier transform infrared spectroscopy. The infrared spectra thereof are as follows: Figure 4 The results show that: by comparing the infrared spectra of carbon dots and α-hydroxydiphenylphosphine oxide carbon dots, after surface modification, the 1747cm -1 The characteristic peak of aldehyde group disappears, while the peak at 700cm -1It is worth noting that at 3100cm -1 There is an obvious characteristic peak of -OH around 3100cm, which indicates that the α-hydroxydiphenylphosphine oxide functional group has been successfully grafted onto the surface of the carbon dots. Comparing the infrared spectra of α-hydroxydiphenylphosphine oxide carbon dots and phosphoryl oxide carbon dots, the peak at 3100cm -1 The characteristic peaks of -OH on the left and right sides are obviously weakened. At the same time, the peaks of 1720 cm -1 The characteristic peak of carbonyl group reappeared around 50 nm, which indicated that the hydroxyl group was oxidized to carbonyl group, and the preparation of phosphoryloxy-type carbon dot photoinitiator was successful.

[0178] Example 7

[0179] The purpose of Example 7 is to illustrate that the phosphoryl oxide carbon dot photoinitiator of Example 1 can effectively initiate the photopolymerization reaction of (meth)acrylate monomers under the irradiation of LED light source.

[0180] Taking the phosphoryloxy carbon dot photoinitiator in Example 1 as an example, 10 mg of the phosphoryloxy carbon dot photoinitiator was mixed with 400 mg of triethylene glycol dimethacrylate (TEGDMA) and ultrasonically shaken for 1 minute to fully dissolve it. 600 mg of diurethane dimethacrylate (UDMA) was added to the mixture and ultrasonically shaken for another 1 minute to fully mix it. The mixture was placed under 200 mW / cm 2 Under the irradiation of 365nm LED, the photopolymerization reaction is carried out, and the obtained photopolymerized film is as follows Figure 5 shown.

[0181] Example 8

[0182] The purpose of Example 8 is to illustrate that the phosphoryl oxide-type carbon dot photoinitiator of Example 1 has a lower mobility.

[0183] Mobility test:

[0184] Taking the phosphoryl oxide carbon dot photoinitiator in Example 1 as an example and commercial TPO as a comparison, a test sample was prepared. Specifically, the photoinitiator (1 wt%) was added to a mixture of UDMA and TEGDMA (6:4) and mixed evenly. 2 Irradiate with 365nm ultraviolet light for 15 minutes for light curing, and rinse the unreacted monomers and initiators on the film surface with ethanol. Take an appropriate amount of film and soak it in ethanol. Monitor the changes in the absorbance value of the solution. The monitoring wavelength of TPO is 380nm, and the monitoring wavelength of carbon dot initiator is 299nm. Figure 6As shown, at 0.5h, the mobility of the phosphoryl oxide type carbon dot photoinitiator was 0.02%, while the mobility of TPO was 5.23%; at 48h, the mobility of the phosphoryl oxide type carbon dot photoinitiator was 2.81%, while the mobility of TPO was 12.35%. Figure 6 The results show that the mobility of the prepared phosphoryl oxide type carbon dot photoinitiator is much lower than that of the commercial photoinitiator TPO.

[0185] Example 9

[0186] The purpose of Example 9 is to illustrate that the phosphoryl oxide-type carbon dot photoinitiator of Example 1 has lower cytotoxicity.

[0187] Cytotoxicity test:

[0188] The cytotoxicity of the photoinitiator was tested using the MTT assay, and commercial TPO was used as a comparison. L929 cells (mouse fibroblasts, provided by Shanghai Biotechnology Co., Ltd.) were seeded in a 96-well plate and cultured with photoinitiators at different concentrations (25, 50, and 100 μg / mL) for 24 hours. The absorbance of each well was measured using a microplate reader (BioTek, USA) at a wavelength of 490 nm. The cell survival rate was calculated according to the following formula 1. The results are shown in Figure 1. Figure 7 The results showed that the phosphoryl oxide carbon dot photoinitiator prepared in Example 1 had lower cytotoxicity than the commercial TPO photoinitiator. At a photoinitiator concentration of 25 μg / mL, the TPO cell survival rate was 89.06%. However, the phosphoryl oxide carbon dot photoinitiator prepared in Example 1 had lower cytotoxicity, with a cell survival rate of 100%.

[0189] Cell survival rate = (A experimental group / A control group) × 100% (Formula 1),

[0190] Among them: A experimental group is the absorbance of the experimental group (with sample added) measured by a microplate reader, and A control group is the absorbance of the control group (without sample added) measured by a microplate reader.

Claims

1. A phosphoryloxy-type carbon dot photoinitiator, wherein the carbon dot surface has a group containing a phosphoryloxy structural portion, and the average particle size of the carbon dot is 1-50 nm. 2 . The phosphoryl oxide-type carbon dot photoinitiator according to claim 1 , wherein the average particle size of the carbon dots is 1-20 nm, preferably 1-15 nm, more preferably 1-10 nm.

3. The phosphoryloxy carbon dot photoinitiator according to claim 1 or 2, wherein the group containing the phosphoryloxy structural portion has a structure as shown in the following formula (1): in: * indicates the connection position with the carbon dots; R1 represents hydrogen, C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C2-C 20 Alkenyl, C3-C 20 Cycloalkenyl, C3-C 10 Cycloalkenyl-C1-C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 Alkyl, wherein the aforementioned C1-C 20 Alkyl, C3-C 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C2-C 20 Alkenyl, C3-C 20 Cycloalkenyl, C3-C 10 Cycloalkenyl-C1-C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 The alkyl group is optionally substituted by one or more groups independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkylthio, C1-C6 alkoxy, Halogen, nitro, amino, cyano, mono(C1-C6 alkyl)amino, di(C1-C6 alkyl)amino and mercapto, and the aforementioned C3-C 20 Cycloalkyl, C3-C 10 Cycloalkyl-C1-C 10 Alkyl, C3-C 20 Cycloalkenyl, C3-C 10 Cycloalkenyl-C1-C 10 Alkyl, C6-C 20 Aryl or C6-C 10 Aryl-C1-C 10 The ring carbon atoms of the alkyl group are optionally replaced by one or more heteroatoms selected from N, S and O.

4. The phosphoryl oxide type carbon dot photoinitiator according to claim 3, wherein: R1 represents hydrogen, C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-C1-C4 alkyl, C2-C 12 Alkenyl, C3-C 12 Cycloalkenyl, C3-C8 cycloalkenyl-C1-C4 alkyl, C6-C 12 Aryl or C6-C 10 Aryl-C1-C4 alkyl, wherein the aforementioned C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-C1-C4 alkyl, C2-C 12 Alkenyl, C3-C 12 Cycloalkenyl, C3-C8 cycloalkenyl-C1-C4 alkyl, C6-C 12 Aryl or C6-C 10 The aryl-C1-C4 alkyl group is optionally substituted by one or more groups independently selected from the group consisting of C1-C4 alkyl, C1-C4 alkylthio, C1-C4 alkoxy, halogen, nitro, amino, cyano, mono(C1-C4 alkyl)amino, di(C1-C4 alkyl)amino and mercapto, and the aforementioned C3-C 12 Cycloalkyl, C3-C8 cycloalkyl-C1-C4 alkyl, C3-C 12 Cycloalkenyl, C3-C8 cycloalkenyl-C1-C4 alkyl, C6-C 12 Aryl or C6-C 10 The ring carbon atoms of the aryl-C1-C4alkyl group are optionally replaced by one or more heteroatoms selected from N, S and O; Preferably, R1 represents hydrogen, C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 Cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl, wherein the aforementioned C1-C 10 Alkyl, C3-C 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 Cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl is optionally substituted by fluorine, chlorine, bromine and C1-C4 alkyl, and the aforementioned C3-C6 10 Cycloalkyl, C3-C6 cycloalkyl-C1-C4 alkyl, C3-C 10 The ring carbon atoms of the cycloalkenyl, C3-C6 cycloalkenyl-C1-C4 alkyl, phenyl or naphthyl are optionally replaced by one or more heteroatoms selected from N, S and O; More preferably, R1 represents hydrogen, C1-C8 alkyl, C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-C1-C2 alkyl, phenyl or naphthyl, wherein the aforementioned C1-C8 alkyl, C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-C1-C2 alkyl, phenyl or naphthyl is optionally substituted by C1-C4 alkyl, and the ring carbon atoms of the aforementioned C3-C8 cycloalkyl, C3-C6 cycloalkyl-C1-C2 alkyl, C3-C8 cycloalkenyl, C3-C6 cycloalkenyl-C1-C2 alkyl, phenyl or naphthyl are optionally replaced by one or more heteroatoms selected from N, S and O.

5. The phosphoryl oxide type carbon dot photoinitiator according to claim 3 or 4, wherein R1 represents hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, cyclopropyl, cyclopentylethyl or phenyl, preferably hydrogen, methyl or methoxy.

6. A method for preparing the phosphoryl oxide type carbon dot photoinitiator according to any one of claims 1 to 5, comprising the following steps: S1: subjecting a compound having at least one aldehyde group and / or hydroxyl group to a carbonization reaction under hydrothermal or solvothermal conditions to obtain carbon dots having aldehyde groups on their surfaces; S2: reacting the carbon dots having aldehyde groups on their surfaces obtained from step S1 with a diphenylphosphine oxide compound to obtain α-hydroxydiphenylphosphine oxide carbon dots; and S3: subjecting the α-hydroxydiphenylphosphine oxide carbon dots from step S2 to oxidation reaction to obtain corresponding phosphoryl oxide-type carbon dot photoinitiators.

7. The method according to claim 6, wherein the compound having at least one aldehyde group and / or hydroxyl group is selected from compounds having a cyclic structure and having at least one aldehyde group and / or hydroxyl group, and linear compounds having at least 5 carbon atoms and having at least one aldehyde group and / or hydroxyl group, wherein the cyclic structure is optionally substituted with one or more groups independently selected from the group consisting of C1-C6 alkyl, C1-C6 alkylthio, C1-C6 alkoxy and halogen; Preferably, the cyclic structure has 5-10 ring members, more preferably 5-8 ring members, for example 5 or 6 ring members, wherein the ring members are C atoms and optionally 1-3 heteroatoms selected from N, O or S, and the cyclic structure is optionally substituted by one or more groups independently selected from the group consisting of C1-C4 alkyl, C1-C4 alkylthio, C1-C4 alkoxy and chlorine.

8. The method according to claim 6 or 7, wherein the compound having at least one aldehyde group and / or hydroxyl group has 1 to 4, such as 1 or 2, aldehyde groups and / or hydroxyl groups; Preferably, the compound having at least one aldehyde group and / or hydroxyl group is of biomass origin, such as furfural, hydroxymethylfurfural, vanillin or cinnamaldehyde.

9. The method according to any one of claims 6 to 8, wherein the solvent in step S1 is selected from C1-C6 alkyl alcohol, preferably ethanol, N,N-dimethylformamide or dimethyl sulfoxide.

10. The method according to any one of claims 6 to 9, wherein the mass ratio of the compound having at least one aldehyde group and / or hydroxyl group to water or solvent is 1:1 to 1:15, preferably 1:2 to 1:

10.

11. The method according to any one of claims 6 to 10, wherein the carbonization temperature in step S1 is 100-250°C, preferably 120-200°C; and / or the pressure is 0.1-3 MPa, preferably 0.2-2 MPa; and / or the reaction time is 4-15 h, preferably 6-12 h.

12. The method according to any one of claims 6 to 11, wherein the reaction of step S2 is carried out in the presence of pyridine, piperidine, triethylamine and / or tetramethylammonium hydroxide, preferably triethylamine, as a catalyst.

13. The method according to any one of claims 6 to 12, wherein in the reaction of step S2, the mass ratio of the carbon dots having aldehyde groups on the surface to the diphenylphosphine oxide compound is 1:1-1:12, preferably 1:1-1:

10.

14. The method according to any one of claims 6 to 13, wherein the diphenylphosphine oxide compound is a compound of formula (Va): wherein R1 is as defined in any one of claims 3 to 5.

15. according to the method for claim 14, wherein said diphenylphosphine oxide compound is selected from diphenylphosphine oxide, bis(p-tolyl)phosphine oxide, bis(p-methoxyphenyl)phosphine oxide, bis(3,5-dimethylphenyl)phosphine oxide, phenylmethylphosphine oxide, phenylethylphosphine oxide, phenylisopropylphosphine oxide and phenyl tert-butylphosphine oxide, preferably diphenylphosphine oxide, bis(p-tolyl)phosphine oxide or bis(p-methoxyphenyl)phosphine oxide.

16. The method according to any one of claims 6 to 15, wherein the oxidation reaction in step S3 is carried out in the presence of one or more of manganese dioxide, hydrogen peroxide, Dess-Martin reagent, potassium permanganate, preferably manganese dioxide as an oxidant. 17 . The method according to claim 16 , wherein the mass ratio of the α-hydroxydiphenylphosphine oxide carbon dots to the oxidant is 1:1-1:12, preferably 1:1-1:

8.

18. Use of the phosphoryl oxide type carbon dot photoinitiator obtained according to any one of claims 1 to 5 or according to any one of claims 6 to 17 as a photoinitiator, especially use as a photoinitiator in a UV-VIS LED light source curing system, especially use as a photoinitiator in a light source curing system with a radiation wavelength of 200-1200 nm, especially 250-660 nm.

19. A photocurable composition comprising at least one phosphoryl oxide type carbon dot photoinitiator obtained according to any one of claims 1 to 5 or according to the method of any one of claims 6 to 17.

20. Cured material obtainable from a photocurable composition according to claim 19.

21. A method for preparing a photocurable material, comprising the step of irradiating the photocurable composition according to claim 19 with a light source having a radiation wavelength of 200-1200 nm, in particular 250-660 nm, such as a UV-VIS LED light source.

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