An antibacterial photocurable resin composition, a method of preparing the same, and an application thereof

Abstract

The present application relates to the technical field of high polymer materials, and particularly relates to an antibacterial photocuring resin composition, a preparation method and application thereof, and provides the antibacterial photocuring resin composition, which comprises the following raw materials in parts by weight: 35-65 parts of polyurethane copolymer, 30-60 parts of active dilution monomer, 0.1-2.0 parts of AIE functional polymer and 1-6 parts of photoinitiator; the AIE functional polymer contains a polymerizable group; the preparation raw materials of the polyurethane copolymer include isocyanate and dihydric alcohol, the dihydric alcohol includes cashew phenolic dihydric alcohol, and the molar percentage of the cashew phenolic dihydric alcohol in the dihydric alcohol is 20-80%. The antibacterial photocuring resin composition provided by the present application has excellent mechanical properties and high curing efficiency, and has long-acting, safe and efficient light-triggered endogenous antibacterial function.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to an antibacterial photocurable resin composition, its preparation method, and its application. Background Technology

[0002] 3D printed dental molds are physical models of teeth created using 3D printing technology, which builds up material layer by layer based on digital oral model data. Compared to traditional dental mold making methods (such as pouring plaster using impression material), 3D printed dental molds offer advantages such as high precision, rapid prototyping, and personalized customization. They are widely used in the dental field, for example, to make orthodontic dental molds, restorations (such as crowns and bridges), and implant guides. These dental molds can be personalized according to the patient's specific needs and oral morphology, significantly improving treatment outcomes and patient satisfaction.

[0003] However, existing 3D printing dental model technology still has some limitations. Major risks may include material performance limitations, printing errors, long-term stability, and biocompatibility. For example, printing errors or defects may affect the accuracy of the dental model. Although digital scanning and design can improve the fit, scanning accuracy, software design errors, or the thickness of printing layers may affect the marginal fit of the prosthesis, leading to food impaction or secondary caries. Furthermore, a small number of patients may experience allergic reactions to the photosensitive resin component in the printing material, manifesting as gingival redness or mucosal irritation.

[0004] Currently, commonly used 3D printing dental mold materials are generally light-cured liquid resins, whose main components include oligomers (such as EA / PUA), monomers, photoinitiators, and other additives. These materials have a smooth surface but are inherently non-antibacterial, providing a smooth but inert surface for bacterial adhesion and colonization, posing a potential risk of biofilm formation.

[0005] To impart antibacterial properties to dental materials, existing technologies have mainly explored two technical approaches, but neither can meet the specific requirements of 3D printed dental models:

[0006] (1) Internally added release-type antibacterial agents: Antibacterial agents such as silver ions, quaternary ammonium salts, chlorhexidine, or antibiotics are physically blended into the resin matrix to achieve antibacterial effects. Its mechanism of action depends on the continuous release and leaching of antibacterial agents. However, this method has two inherent drawbacks: first, the antibacterial agents are rapidly depleted in the body fluid environment, resulting in unsustainable antibacterial effects; second, the migration of additives may degrade the mechanical properties of the material, and some metal ions or organic antibacterial agents pose a risk of cytotoxicity, raising questions about long-term biosafety.

[0007] (2) Surface post-treatment modification: Apply an antibacterial coating to the surface of the formed printed part or graft antibacterial molecules using technologies such as plasma. This method has problems such as complex process, high cost, and poor repeatability. Most importantly, any surface coating will introduce additional thickness (usually on the micrometer level), which is unacceptable for dental models with extremely high precision requirements (edge ​​fit error needs to be controlled within tens of micrometers), and will directly lead to clinical failures such as poor placement of restorations and occlusal interference.

[0008] In summary, existing antibacterial technologies for 3D-printed dental mold materials either fail to meet practical clinical needs due to short-lived effects, safety risks, or compromise of crucial dimensional accuracy. Therefore, there is an urgent need in the field to develop a novel 3D printing material that can meet the high-precision molding requirements of dental applications while possessing safe and long-lasting intrinsic antibacterial properties to overcome the shortcomings of existing technologies. Summary of the Invention

[0009] This invention provides an antibacterial photocurable resin composition, its preparation method, and its application, to address the shortcomings of existing 3D printed dental model materials, such as the lack of long-lasting and safe antibacterial function, and the defects of existing antibacterial modification methods, such as the easy migration of antibacterial agents leading to short-lived effects and biosafety risks, or the damage of surface coatings to the critical dimensional accuracy of the model. The invention achieves a material with visible light-triggered, long-lasting, stable, safe, and non-migrating antibacterial function, while maintaining excellent mechanical properties, high printing accuracy, and biosafety.

[0010] This invention provides an antibacterial photocurable resin composition comprising the following raw materials in parts by weight: 35-65 parts of polyurethane copolymer, 30-60 parts of reactive diluent monomer, 0.1-2.0 parts of AIE functional polymer, and 1-6 parts of photoinitiator;

[0011] The AIE functional polymer contains polymerizable groups; the raw materials for preparing the polyurethane copolymer include isocyanate and diol, the diol including cashew nut glycol, and the cashew nut glycol accounting for 20-80% of the molar percentage of the diol.

[0012] The antibacterial photocurable resin composition provided by this invention combines a polyurethane copolymer containing a specific proportion of cashew nut shell diol, an active diluent monomer, a covalently bondable AIE functional polymer, and a photoinitiator. The synergistic effect of these components solves the fundamental problem of existing 3D printed dental mold materials lacking long-lasting and safe antibacterial properties. This invention utilizes the unique microphase separation structure formed by cashew nut shell diol in polyurethane to provide a rigid nano-environmental confinement for the AIE functional polymer, thereby greatly enhancing its photodynamic antibacterial efficiency in generating reactive oxygen species (ROS) under light irradiation. Simultaneously, the polymerizable groups on the AIE functional polymer allow it to be firmly anchored in the resin matrix network through chemical bonds during photocuring, ultimately resulting in a resin composition that combines excellent mechanical properties and high curing efficiency with long-lasting, safe, and highly efficient phototriggered endogenous antibacterial function.

[0013] The present invention provides an antibacterial photocurable resin composition comprising the following raw materials in parts by weight: 40-60 parts of polyurethane copolymer, 40-55 parts of reactive diluent monomer, 0.5-1.0 parts of AIE functional polymer and 2-4 parts of photoinitiator.

[0014] According to the antibacterial photocurable resin composition of the present invention, the raw materials for preparing the AIE functional polymer, by weight, include: 80-120 parts of 4-bromoaniline, 100-150 parts of p-iodoanisole, 250-300 parts of BBr3, 75-100 parts of 5-aldehyde-2-thiopheneboronic acid, 20-40 parts of a first acrylate compound, and 10-20 parts of a second acrylate compound; wherein, the first acrylate compound is selected from one or more of ethyl isocyanate, allyl isocyanate, and isocyanoethyl methacrylate; and the second acrylate compound is selected from one or more of methyl acrylate, methyl methacrylate, octyl acrylate, and isobornyl acrylate.

[0015] In this invention, 4-bromoaniline and 5-aldehyde-2-thiopheneboronic acid are aggregation-induced emission (AIE) core molecules with highly efficient photodynamic activity in the raw materials for preparing the AIE functional polymer. The introduced first acrylate compound (such as ethyl isocyanate) serves as a polymerizable group acting as a chemical anchor, transforming the original AIE core molecule into a copolymerizable reactive monomer. This ensures that it can be permanently fixed in the final resin network through stable covalent bonds, enhancing its fluorescence emission and increasing its reactive oxygen species (ROS, mainly singlet oxygen) quantum yield. This fundamentally solves the problems of antibacterial agent migration and exudation leading to effect attenuation and biosafety risks, endowing the material with long-lasting, stable, and highly biocompatible endogenous antibacterial capabilities. The introduction of a second acrylate compound (such as methyl acrylate) as a comonomer enables more precise molecular engineering control.

[0016] According to the antibacterial photocurable resin composition of the present invention, the preparation method of the AIE functional polymer includes the following steps:

[0017] S1. Compound 1 was prepared by coupling 4-bromoaniline with p-iodoanisole.

[0018] S2. Compound 1 is demethylated to obtain compound 2;

[0019] S3. Compound 2 and 5-aldehyde-2-thiopheneboronic acid were subjected to a Suzuki-Miyaura reaction to prepare compound 3;

[0020] S4. Compound 3 is reacted with the first acrylate compound in a Williamson reaction to form an AIE monomer with a triphenylamine-based structure containing acrylate double bonds.

[0021] S5. The obtained AIE monomer is subjected to photopolymerization reaction with a second acrylate compound to obtain AIE functional polymers with different molecular weights.

[0022] According to the antibacterial photocurable resin composition of the present invention, the preparation method of the AIE functional polymer includes the following steps:

[0023] S1. 4-Bromoaniline, p-iodoanisole, 1,10-phenanthroline monohydrate, CuCl, KOH, and toluene are stirred at 100-120°C for 24-48 h to obtain compound 1. Preferably, the molar ratio of 4-bromoaniline to p-iodoanisole is 1:(1-1.5); the molar amount of 1,10-phenanthroline monohydrate is 5-15% of the molar amount of 4-bromoaniline; the molar amount of CuCl is 5-15% of the molar amount of 4-bromoaniline; and the molar amount of KOH is 5-15 times the molar amount of 4-bromoaniline.

[0024] S2. Slowly add BBr3 to a mixture of compound 1 and dichloromethane at -25°C to -15°C. Heat the mixture to room temperature, stir for 3-5 hours, and then pour it into a saturated aqueous solution of sodium bicarbonate. Dry the organic layer on anhydrous magnesium sulfate and purify by column chromatography to obtain compound 2. Preferably, the molar amount of BBr3 is 2-4 times the molar amount of compound 1.

[0025] S3. A mixture of compound 2, 5-aldehyde-2-thiopheneboronic acid, Pd(dppf)Cl2, and K2CO3 is added to a flask containing DMF. The reaction mixture is stirred at 70-80°C for 14-18 h to obtain compound 3. Preferably, the molar amount of 5-aldehyde-2-thiopheneboronic acid is 1.5-2 times the molar amount of compound 2.

[0026] S4. Compound 3, AOI isocyanate ethyl acrylate, K2CO3, and acetonitrile (CH3CN) are stirred at 80-90℃ for 16-20 h to obtain the AIE monomer. Preferably, the molar amount of AOI isocyanate ethyl acrylate is 1.0-1.5 times the molar amount of compound 3; the molar amount of K2CO3 is 2-4 times the molar amount of compound 3.

[0027] S5. Add AIE monomer and MMA to the reaction tube separately. Add THF and sonicate until dissolved, then add photoinitiator TPO and mix thoroughly by shaking. Insert a nitrogen syringe below the liquid surface to purge oxygen, and seal the reaction tube under nitrogen purging. Irradiate with a 365nm UV lamp (2-5cm distance) for 30-50 minutes to obtain a viscous polymerization product. Preferably, the molar ratio of AIE monomer to MMA is 1:(1-1.5); the amount of photoinitiator is 1-3% of the total monomer mass.

[0028] This experiment achieved controllable preparation of low, medium, and high molecular weight gradients by adjusting the light exposure time and nitrogen deoxygenation conditions. All reactions were carried out in 10 mL reaction tubes.

[0029] According to the antibacterial photocurable resin composition of the present invention, the number average molecular weight of the AIE functional polymer is 1000-5000 Da, preferably 2000-4000 Da, and more preferably 3000 Da.

[0030] In the antibacterial photocurable resin composition according to the present invention, the cashew phenol diol accounts for 40-60% of the molar percentage of the diol.

[0031] According to the antibacterial photocurable resin composition of the present invention, the diol further includes polycaprolactone diol, wherein the number average molecular weight of the polycaprolactone diol is 1000-5000 Da.

[0032] This invention introduces polycaprolactone diol within a specific molecular weight range into the soft segments of polyurethane, achieving synergistic optimization of material mechanical properties and antibacterial activity. On one hand, as a flexible segment, the addition of polycaprolactone diol significantly improves the flexibility, toughness, and impact strength of the cured resin, mitigating the brittleness that may result from high crosslinking density and making it less prone to breakage while meeting the precision requirements of dental molds. On the other hand, in contrast to the rigid diols (such as cashew phenol diol) already present in the system, it helps to strengthen and finely control the microphase separation structure of the polyurethane, providing a more ideal nano-environment for AIE functional polymers that combines flexible buffering with rigid confinement. This further enhances the photodynamic antibacterial effect, ultimately achieving a combination of high toughness and efficient, long-lasting antibacterial performance.

[0033] According to the antibacterial photocurable resin composition of the present invention, the molar ratio of the isocyanate to the diol is (1-1.1):1.

[0034] According to the antibacterial photocurable resin composition of the present invention, the raw materials for preparing the polyurethane copolymer further include functional monomers, wherein the functional monomers are selected from one or more of acrylates or methacrylates; the molar amount of the functional monomers is 0.5-2% of the molar amount of the isocyanate.

[0035] This invention introduces functional monomers with polymerizable double bonds during the polyurethane synthesis stage, directly grafting photocuring reaction sites onto the core skeletal component of polyurethane. This allows not only small-molecule reactive diluent monomers to participate in crosslinking during photocuring, but also the polyurethane macromolecules themselves to become part of the crosslinking network, thus significantly increasing the crosslinking density of the final cured product. This higher crosslinking density directly translates into a substantial improvement in the material's mechanical properties, such as strength, hardness, and modulus, and enhances its dimensional stability and chemical resistance. It also facilitates more complete curing, reduces the content of harmful residual monomers, and thereby improves the material's biocompatibility.

[0036] According to the antibacterial photocurable resin composition of the present invention, the method for preparing the polyurethane copolymer includes: using isophorone diisocyanate (IPDI) as the hard segment source, polycaprolactone diol (PCL) and bio-based cashew nutshell oil derivative (cashew phenolic diol) as the soft segment and functional segment, and in combination with the chain extender trimethylolpropane monoallyl ether, to synthesize a photocurable polyurethane (PU) containing side groups in one step.

[0037] According to the antibacterial photocurable resin composition of the present invention, the preparation method of the polyurethane copolymer includes the following steps:

[0038] Under nitrogen protection, isophorone diisocyanate and the catalyst dibutyltin dilaurate (DBTDL) are heated to 70-90°C, and a mixed diol composed of polycaprolactone diol and cashew nut shell polyoxypropylene ether diol is added dropwise. The reaction is maintained at this temperature for 1-3 hours, and the -NCO content is monitored by titration using the di-n-butylamine method until the theoretical value is reached. Preferably, the amount of DBTDL used is 0.01-0.1% of the total material mass.

[0039] Cool the system to 40-60°C, add the chain extender trimethylolpropane monoallyl ether (TMPAE), and heat to 70-80°C to continue the reaction for 2-4 hours. Preferably, the molar amount of TMPAE is 10-30% of the molar amount of isophorone diisocyanate.

[0040] Cool the temperature again to 40-50℃, add the polymerization inhibitor p-hydroxyanisole and excess hydroxyethyl methacrylate (HEA), and react at 50-70℃ until the IR spectrum reaches 2270 cm⁻¹. -1 The -NCO characteristic peak at the point completely disappeared. The molar amount of HEA was 0.5-2% of the molar amount of isophorone diisocyanate. Residual solvent was removed by rotary evaporation to obtain a pale yellow viscous liquid.

[0041] According to the antibacterial photocurable resin composition of the present invention, the active diluent monomer is selected from one or more of hydroxyethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA), bisphenol A dimethacrylate (Bis-GMA), and urethane dimethacrylate (UDMA).

[0042] The antibacterial photocurable resin composition according to the present invention further includes, optionally, 0-3 parts of additives. Additives include polymerization inhibitors (such as p-hydroxyanisole, BHT), leveling agents, colorants, etc.

[0043] According to the antibacterial photocurable resin composition of the present invention, the photoinitiator is selected from one or more of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), camphorquinone (CQ), 2-hydroxy-2-methyl-1-phenylpropanone, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0044] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-mentioned antibacterial photocurable resin composition, comprising: reacting a polyurethane copolymer, an active diluent monomer, an AIE functional polymer and a photoinitiator at 50-60°C under light-protected conditions for 1-3 hours.

[0045] The preparation method of the antibacterial photocurable resin composition provided by this invention involves mixing at a specific temperature of 50-60°C, which significantly reduces the viscosity of high molecular weight components, ensuring complete and uniform physical dispersion of all components, especially the key AIE functional polymers. Secondly, operation under light-protected conditions avoids accidental activation of the photoinitiator, preventing premature polymerization of the resin and ensuring good storage stability and processing suitability for 3D printing. The preparation method provided by this invention is highly compatible with conventional polyurethane synthesis processes, requires no complex or expensive post-processing equipment, has a simple production process, and controllable costs, making it ideal for large-scale industrial production.

[0046] According to a third aspect of the invention, the invention also provides the application of the above-described antibacterial photocurable resin composition in 3D printed dental molds.

[0047] The antibacterial light-cured resin composition provided by this invention combines aggregation-induced emission (AIE) polymers with biomass polyurethane to prepare a dental resin that can generate antibacterial activity upon visible light excitation. Based on the principle of photodynamic antimicrobial therapy (PDAT), this material generates cytotoxic reactive oxygen species (ROS) through the interaction of a photosensitizer and oxygen under light irradiation, thereby achieving highly efficient and broad-spectrum killing of bacteria without easily inducing bacterial resistance. 3D printing using this resin can produce dental molds with visible light-induced antibacterial function, providing a new technical approach to improving the antibacterial properties of existing materials. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] In the following examples and comparative examples, the component amounts are all expressed in parts by weight. Unless otherwise specified, each part by weight is 1 g.

[0050] The testing methods for each performance aspect are as follows:

[0051] Molecular weight testing methods:

[0052] Gel permeation chromatography (GPC) was used to determine the molecular weight (Mn) and molecular weight distribution (PDI) of polymers. The molecular weight and distribution of the samples were determined using a GPC instrument (LC98IIR model) manufactured by Beijing Wenfen Analytical Instrument Technology Development Co., Ltd. Tetrahydrofuran (THF) was used as the mobile phase, the sample concentration was 5 mg / mL, polystyrene standard was used as the universal calibration curve, the column temperature was 40℃, and the flow rate was set to 0.80 mL / min.

[0053] Mechanical property testing methods:

[0054] Mechanical property testing was conducted according to the national standard GB / T1040-2018. At 25℃, dumbbell-shaped specimens (narrowest part 15mm long, 4mm wide, and 1mm thick) were tested on a SANS CMT6000 universal testing machine with a clamping speed of 10mm / min. Five specimens were tested, and the average value was taken.

[0055] Fluorescence quantum yield assay method: The fluorescence quantum yield was measured using a FluoroSENS-9003 fluorescence spectrometer (China). To determine the relative luminescence quantum yield, AIE monomer solutions (water and methanol) with a maximum absorbance value below 0.05 (at 480 nm wavelength) were first prepared. The results were compared with the standard RhB in methanol. The calculation was performed using the following formula:

[0056]

[0057] In the formula, Indicates the quantum yield of the sample to be tested; The quantum yield of the standard sample is 43%. and , respectively, are the refractive indices of the standard solution (methanol) and the sample solution (water), where =1.333, =1.327; and These are the integrated areas of emission intensity in the fluorescence spectra of the sample and the standard solution, respectively. and These represent the absorption intensities of the sample and standard sample solutions, respectively.

[0058] Reactive oxygen species (ROS) testing methods:

[0059] A polyurethane composite film was immersed in a prepared dichlorofluorescein diacetate (DCF-DA) solution. The fluorescence intensity of the sample solution was collected and measured under different white light irradiation times. During the measurement process, the sample was exposed to excitation light at 488 nm, and the fluorescence emission spectrum from 490 to 600 nm was measured. 9,10-Anthracene-bis(methylene)dimalonic acid (ABDA), as another important ROS indicator, plays a crucial role under oxidative stress conditions, particularly in the generation of reactive oxygen species. The absorption spectrum of ABDA at 378 nm was recorded under different white light irradiation times. The absorption of ABDA at 378 nm under different irradiation times was recorded to obtain the attenuation rate of the photosensitized process. The singlet oxygen quantum yield under white light irradiation was also measured. Calculated using equation (1):

[0060] Equation (1).

[0061] In the formula, and represents the decomposition rate constants of ABDA on the sample and RB, respectively. and The values ​​represent the light absorbed by the sample and RB, respectively, and are determined by area integration over the absorption band in the wavelength range of 400-700 nm. The reactive oxygen quantum yield was measured in water and was 0.75.

[0062] Antibacterial test method:

[0063] The antibacterial effects of polyurethane composite films were evaluated using Staphylococcus aureus ATCC6538, Escherichia coli ATCC25922, and methicillin-resistant Staphylococcus aureus ATCC29213.

[0064] Before the experiment, all materials were sterilized. Staphylococcus aureus, Escherichia coli, and methicillin-resistant Staphylococcus aureus were then incubated at 37 °C for 1 hour. The polyurethane composite film was cut into 1 cm x 1 cm square samples. A bacterial suspension (20 μL, 10⁷ CFU / mL) was then added to the sample surface, and three experimental control groups were formed. The light group was irradiated under white light for 1 hour, the dark group was incubated in the dark for 1 hour, and the blank group was untreated and incubated for 1 hour. After 1 hour, the materials were rinsed with 1 mL of sterile water, and 20 μL of the eluent was plated under suitable conditions (37 °C). After 12 hours, the colony count was calculated to obtain the sterilization rate.

[0065] Example 1

[0066] This embodiment provides an antibacterial photocurable resin composition comprising the following raw materials in parts by weight: 50 parts of polyurethane copolymer Bio-PUA-40, 30 parts of Bis-GMA, 19 parts of TEGDMA, 1.0 part of AIE functional polymer, and 3 parts of photoinitiator TPO, wherein the number average molecular weight of the AIE functional polymer is 3000 Da.

[0067] This embodiment also provides a method for preparing an antibacterial photocurable resin composition, comprising the following steps:

[0068] 1. Preparation of AIE functional polymers:

[0069] S1. Take 10.0 g (58.1 mmol) of 4-bromoaniline, 11.3 g (48.4 mmol) of p-iodoanisole, 0.8 g (4.03 mmol) of 1,10-phenanthroline monohydrate, 0.4 g (4 mmol) of CuCl, 22.6 g (403 mmol) of KOH, and 200 mL of toluene. Stir the resulting solution at 110 °C for 36 h. Then, cool the reaction mixture to room temperature and evaporate the solvent. Dilute the residue with 200 mL of dichloromethane and wash with 3 x 100 mL of deionized water. Evaporate the solvent to obtain the crude compound. Purify the crude product by column chromatography to obtain pure compound 1 (13 g, 91%), which is a clear oily liquid.

[0070] S2. Compound 1 (3.4 g, 9.6 mmol) and dichloromethane (100 mL) were slowly added to BBr3 (7.2 g, 28.8 mmol) at -20 °C. The mixture was heated to room temperature and stirred for 4 h before being poured into a saturated aqueous solution of sodium bicarbonate. The organic layer was dried over anhydrous magnesium sulfate. The mixture was purified by column chromatography to obtain compound 2 (3.0 g, 92%).

[0071] S3. A mixture of compound 2 (8.7 g, 24.4 mmol), 5-aldehyde-2-thiopheneboronic acid (6.7 g, 43.2 mmol), Pd(dppf)Cl2 (0.9 g, 1.2 mmol, 10 mol%), and K2CO3 (17.6 g, 127.2 mmol) was added to a 250 mL Schlenk flask containing 100 mL of DMF. The reaction mixture was stirred at 75 °C. After 16 h, the reaction mixture was filtered to remove the organic solvent. The residue was dissolved in DCM. After washing with water, the mixture was dried over anhydrous MgSO4 to evaporate the solvent. The residue was purified by silica gel chromatography to give compound 3 (4.9 g, 52.6%).

[0072] S4. Compound 3 (1.4 g, 3.8 mmol), ethyl acrylate (AOI isocyanate) (0.71 g, 5 mmol), K₂CO₃ (1.6 g, 11.4 mmol), and acetonitrile (CH₃CN, 100 mL) were added to a 250 mL round-bottom flask. The mixture was stirred at 85 °C for 18 h, cooled to room temperature, and filtered to remove insoluble inorganic salts. The acetonitrile solution was concentrated under vacuum. The crude product was purified by column chromatography to give the AIE monomer (1.6 g, 86%).

[0073] S5. Add AIE monomer (51.2 mg, 0.1 mmol) and MMA (10 mg, 0.1 mmol) to 10 mL reaction tubes respectively. Add 2-3 mL of THF and sonicate until dissolved. Then add 1.2 mg of photoinitiator TPO (2 wt% of total monomer mass) and shake to mix. Insert a nitrogen syringe below the liquid surface and purge with nitrogen for 5 min to remove oxygen. Seal the reaction tube under nitrogen purging. Irradiate with a 365 nm UV lamp (3 cm away) for 40 min to obtain a viscous polymerization product. Pour the polymerization solution into 15-20 mL of ice-cold methanol, centrifuge to collect the yellow precipitate, and vacuum dry to constant weight to obtain the target copolymer.

[0074] This experiment achieved controllable preparation of low, medium, and high molecular weight gradients by adjusting the light exposure time and nitrogen deoxygenation conditions. All reactions were carried out in 10 mL reaction tubes.

[0075] 2. Synthesis of Bio-based Polyurethane Acrylate Oligomers (Bio-PUA)

[0076] Under dry nitrogen protection, isophorone diisocyanate (IPDI, 100 mmol) and dibutyltin dilaurate catalyst (DBTDL, 0.05 wt% of total material) were added to a reaction flask equipped with a stirrer, temperature control, and condenser. The temperature was raised to 80 °C, and a mixed diol (total hydroxyl group 100 mmol) consisting of polycaprolactone diol (PCL-2000, 60 mmol) and cardanol-based polyoxypropylene ether diol (Cardanol-PPG, Mn=2000, 40 mmol) was slowly added dropwise. The reaction was maintained at this temperature for 2 hours, and the -NCO content was monitored by titration using the di-n-butylamine method until the theoretical value was reached.

[0077] The system was cooled to 50°C, and the chain extender trimethylolpropane monoallyl ether (TMPAE, 20 mmol) was added. The temperature was then raised to 75°C and the reaction continued for 3 hours.

[0078] The temperature was lowered again to 45°C, and the polymerization inhibitor p-hydroxyanisole (100 ppm) and excess hydroxyethyl methacrylate (HEA, 1 mmol, used for end-capping and introducing double bonds) were added. The reaction was carried out at 60°C until the IR spectrum reached 2270 cm⁻¹. -1 The -NCO characteristic peak at that location completely disappeared.

[0079] The residual solvent was removed by rotary evaporation, yielding a pale yellow viscous liquid, denoted as Bio-PUA-40 (where 40 represents the molar percentage of the cashew nut shell oil derivative diol in the soft segment).

[0080] The components were mixed uniformly at 55°C under light-protected conditions for 2 hours, followed by vacuum degassing for 1 hour to obtain the various antibacterial light-curing resin compositions.

[0081] Example 2

[0082] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that it includes the following raw materials in parts by weight: 50 parts of polyurethane copolymer Bio-PUA-40, 30 parts of Bis-GMA, 19.5 parts of TEGDMA, 0.5 parts of AIE functional polymer, and 3 parts of photoinitiator TPO.

[0083] Example 3

[0084] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that it includes the following raw materials in parts by weight: 50 parts of polyurethane copolymer Bio-PUA-40, 30 parts of Bis-GMA, 18.5 parts of TEGDMA, 1.5 parts of AIE functional polymer, and 3 parts of photoinitiator TPO.

[0085] Comparative Example 1

[0086] This comparative example provides an antibacterial photocurable resin composition, which differs from Example 1 in that an equal amount of chitosan (Mw < 5000 Da) is used instead of the AIE functional polymer. The chitosan is sourced from Shanghai Maclean Biochemical Technology Co., Ltd.

[0087] Comparative Example 2

[0088] This comparative example provides an antibacterial photocurable resin composition that differs from Example 1 in that it includes the following raw materials in parts by weight: 50 parts of urethane dimethacrylate (UDMA), 30 parts of Bis-GMA, 19 parts of TEGDMA, and 1.0 part of AIE functional polymer.

[0089] This comparative example also provides the antibacterial photocurable resin composition, comprising the following steps: mixing urethane dimethacrylate (UDMA), Bis-GMA and TEGDMA evenly, then adding AIE functional polymer for direct physical blending, stirring to disperse evenly and then curing.

[0090] Comparative Example 3

[0091] This comparative example provides an antibacterial photocurable resin composition, which differs from Example 1 in that an equal amount of methacryloyloxyethyltrimethylammonium chloride (METAC) homopolymer (Mw=3000) is used instead of the AIE functional polymer.

[0092] METAC was purchased from Shanghai McLean Biochemical Technology Co., Ltd.

[0093] Experimental Example 1

[0094] 1. Real-time antibacterial performance test (for Streptococcus mutans)

[0095] According to ISO 22196, the antibacterial light-cured resin composition samples of Examples 1-3 and Comparative Examples 1-3 were incubated with a suspension of Streptococcus mutans (S. mutans ATCC 35668) for 24 hours. Before the experiment, the surface of all samples was irradiated with a dental light-curing lamp for 20 seconds. The antibacterial rate (%) was determined by calculating colony forming units (CFU).

[0096] Results: See Table 1. The data show that the samples of the present invention exhibit near-complete immediate antibacterial properties. Among them, Example 1 achieves the best balance between effectiveness and material properties.

[0097] Table 1: Antibacterial rate of sample surface in contact (24h, after light triggering)

[0098]

[0099] 2. Long-lasting antibacterial performance test (simulating the aging of the oral environment)

[0100] The samples were immersed in simulated artificial saliva at 37°C and circulated 10,000 times in a hot and cold cycler (4°C / 55°C, 1 minute each) (approximately equivalent to 3 months in the oral cavity). Before and after aging, samples were taken for the same antibacterial test as in Experiment 1. The retention rate of antibacterial rate before and after aging (antibacterial rate after aging / initial antibacterial rate × 100%) was used as the core indicator of long-lasting effectiveness.

[0101] Results: See Table 2. The data strongly demonstrate that only the sample of this invention maintained nearly unchanged high antibacterial activity. Comparative Example 2 showed a sharp loss of performance, highlighting the AIE component migration problem.

[0102] Table 2: Long-lasting antibacterial properties of samples after simulated aging

[0103]

[0104] 3. Biosafety testing (cytotoxicity and migration assessment)

[0105] Sample extracts were prepared according to ISO 10993-5 standard (samples were immersed in cell culture medium at 37°C for 72 hours). Mouse fibroblasts (L929) were cultured with the extracts for 24 and 72 hours, and the relative cell proliferation rate (RGR) was determined using the CCK-8 assay to assess cytotoxicity. An RGR ≥ 90% was considered safe.

[0106] Results: See Table 3. The sample extract of Example 1 of this invention showed no cytotoxicity, proving that the AIE component was firmly bound and did not migrate. In contrast, the sample extract of Comparative Example 2 exhibited severe cytotoxicity, directly demonstrating that migrating additives pose a biosafety risk.

[0107] Table 3: Relative proliferation rate (RGR) of L929 cells by sample extracts

[0108]

[0109] 4. Key mechanical properties and conversion rate testing

[0110] Double bond conversion (DC%, by FTIR), flexural strength (FS, MPa), and flexural modulus (FM, GPa) were tested to demonstrate that the material’s fundamental mechanical properties were not impaired by the introduction of functional components.

[0111] Results: See Table 4. The sample of Example 1 of this invention exhibited excellent comprehensive performance, with mechanical properties comparable to commonly used clinical resins. It also had a high conversion rate, indicating that the material was fully cured with few residual monomers, further ensuring biosafety.

[0112] Table 4: Mechanical properties and double bond conversion rate of the samples

[0113]

[0114] Based on the above experimental data, the following conclusions can be drawn:

[0115] The antibacterial photocurable resin composition of the present invention maintains an antibacterial retention rate of nearly 100% after rigorous simulated aging (Table 2), while the retention rate of Comparative Example 2 drops sharply to 15.5%. This comparison demonstrates that chemical bonding is the fundamental way to solve the problem of unsustainable antibacterial effects.

[0116] The extract of the antibacterial photocurable resin composition of the present invention exhibits grade 0 cytotoxicity (Table 3), while the extract of Comparative Example 2 shows significant cytotoxicity (72h RGR of only 42.1%). This confirms that simple physical addition can lead to the migration of AIE components, posing a safety hazard, while the present invention eliminates this risk through chemical bonding.

[0117] Compared with Comparative Example 1, the antibacterial photocurable resin composition of the present invention has made a qualitative leap in antibacterial efficiency (especially after light triggering) and long-lasting effect, demonstrating the significant advantages of the AIE mechanism over the traditional contact antibacterial mechanism.

[0118] Compared with Comparative Example 3, the antibacterial photocurable resin composition of the present invention is superior in terms of broad-spectrum antibacterial activity (especially against anaerobic bacteria), speed of action, and long-lasting effect, indicating that the photodynamic antibacterial pathway of AIE functional polymers is unique and inventive.

[0119] The antibacterial photocurable resin composition of the present invention achieves a balance of high antibacterial activity, extreme long-lasting effect, excellent biocompatibility and good mechanical properties through the synergistic effect of AIE functional monomers and cashew nut shell oil-based PUA resin that can construct a multiphase separation network. Comparative Examples 1-3 could not achieve this balance of properties at the same time.

[0120] Example 4

[0121] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that Bio-PUA-20 is used instead of Bio-PUA-40.

[0122] Example 5

[0123] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that Bio-PUA-60 is used instead of Bio-PUA-40.

[0124] Example 6

[0125] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that Bio-PUA-80 is used instead of Bio-PUA-40.

[0126] Comparative Example 4

[0127] This comparative example provides an antibacterial photocurable resin composition, which differs from Example 1 in that Bio-PUA-0 is used instead of Bio-PUA-40.

[0128] The mechanical properties, fluorescence quantum yield, and reactive oxygen species (ROS) yield of Examples 1, 4-6, and Comparative Example 4 are compared in Table 5 below.

[0129] Table 5

[0130]

[0131] As shown in Table 5, the experimental data indicate that from 0 to 40% molar concentration of PU, the introduction of an appropriate amount of cashew nut shell oil diol into the soft segments improves microphase separation, making the hard segment microregions purer and more orderly arranged, thereby enhancing their effective strength as physical crosslinking points. Simultaneously, the increased rigidity of the soft segments themselves allows for more effective load transfer and distribution, leading to a gradual increase in tensile strength; however, beyond PU-40, phase separation may decrease. With increasing cashew nut shell oil diol proportion in the soft segments, the material modulus increases, while the elongation at break decreases. A PU molar concentration of 40% achieves the optimal balance between toughness and rigidity.

[0132] From 0 to 40% molar concentration of PU, the degree of microphase separation improved and the rigidity of the soft segment increased with the increase of the proportion of cashew nut shell oil-based diol in the soft segment, thus strengthening the π-interaction with the AIE unit. This together led to an enhanced confinement effect on the AIE chromophore and suppression of non-radiative decay channels. Therefore, both the AIE fluorescence quantum yield and ROS yield were significantly improved, reaching a peak near a PU molar concentration of 40%.

[0133] With PU molar concentrations ranging from 40% to 80%, the excessively high proportion of cashew nut shell oil-based diol in the soft segments reduces the chemical difference between the soft and hard segments, potentially leading to microphase mixing. This blurs the boundaries of the hard segment microregions, weakening their rigid confinement ability. Simultaneously, the high content of aromatic rings may cause unfavorable aggregation or self-quenching of AIE units. Consequently, luminescence and ROS yields decrease.

[0134] Example 7

[0135] This embodiment provides an antibacterial light-curing resin composition, which differs from Example 1 in that the amount of AIE functional polymer used is 0.1 parts.

[0136] Example 8

[0137] This embodiment provides an antibacterial light-curing resin composition, which differs from Example 1 in that the amount of AIE functional polymer is 2 parts.

[0138] The comparison of fluorescence quantum yield and ROS yield in Examples 1-3, 7 and 8 is shown in Table 6 below.

[0139] Table 6

[0140]

[0141] As shown in Table 6, the fluorescence intensity significantly increased with the addition of AIE functional polymer from 0.1 parts to 1 part. This is because AIE molecules are fully dispersed and effectively captured and confined by the hard-segment microregions of PU-40. At this point, each AIE unit is in an ideal rigid environment, intramolecular rotation is sufficiently restricted, and non-radiative decay is suppressed, thus the luminescence efficiency (fluorescence quantum yield) approaches its maximum value. The fluorescence intensity in this range is essentially linearly positively correlated with the AIE concentration.

[0142] As the amount of AIE functional polymer added increases from 1 part to 2 parts, the fluorescence intensity increase slows down and may decline after reaching a peak. This is because the excess AIE functional polymer exceeds the capacity of the PU hard segment microregions, causing some AIE units to aggregate in the more compatible soft segment region or form self-aggregates. This non-ideal aggregation may lead to the ACQ effect, where π-π stacking occurs between AIE units, forming excitoassociates and resulting in nonradiative energy transfer. Another reason is the formation of larger aggregates, causing light scattering and reducing the effective excitation light intensity and emitted fluorescence.

[0143] As the amount of AIE functional polymer added increased from 0.1 parts to 1 part, the fluorescence intensity significantly improved. The ROS yield increased rapidly with increasing AIE functional polymer content. The rigid confinement environment also greatly promoted intersystem crossing (ISC). Well-dispersed AIE photosensitizers exhibit high triplet quantum yields and long lifetimes, and the PU matrix allows oxygen diffusion, resulting in highly efficient ROS yields.

[0144] As the amount of AIE functional polymer added increases from 1 part to 2 parts, the ROS yield increases to saturation or even decreases. At high concentrations, triplet excitons of adjacent AIE units collide and annihilate each other, resulting in energy loss. The self-aggregates of AIE may hinder oxygen permeation, preventing the triplet excitons generated inside from reacting with oxygen.

[0145] Example 9

[0146] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that the number-average molecular weight of the AIE functional polymer is 1000 Da. The preparation method of the AIE functional polymer is similar to that of Example 1, and the molecular weight gradient can be controlled by adjusting the light irradiation time and nitrogen deoxygenation conditions.

[0147] Example 10

[0148] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that the number-average molecular weight of the AIE functional polymer is 2000 Da. The preparation method of the AIE functional polymer is similar to that of Example 1, and the molecular weight gradient can be controlled by adjusting the light irradiation time and nitrogen deoxygenation conditions.

[0149] Example 11

[0150] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that the number-average molecular weight of the AIE functional polymer is 4000 Da. The preparation method of the AIE functional polymer is similar to that of Example 1, and the molecular weight gradient can be controlled by adjusting the light irradiation time and nitrogen deoxygenation conditions.

[0151] Example 12

[0152] This embodiment provides an antibacterial photocurable resin composition, which differs from Example 1 in that the number-average molecular weight of the AIE functional polymer is 5000 Da. The preparation method of the AIE functional polymer is similar to that of Example 1, and the molecular weight gradient can be controlled by adjusting the light irradiation time and nitrogen deoxygenation conditions.

[0153] The comparison of fluorescence quantum yield and ROS yield for Examples 1, 9-12 is shown in Table 7 below.

[0154] Table 7

[0155]

[0156] As can be seen from the experimental results in Table 7, when the molecular weight of the AIE functional polymer is between 1000-2000 Da, due to the short polymer chain, high mobility, and easy dispersion, it can penetrate and disperse more deeply in the hard segment microregions of PU. It is "anchored" by multiple hard segment microregions, resulting in a strong and uniform confinement effect. This leads to a moderate local concentration of AIE units, high ISC efficiency, and good dispersion, which is conducive to oxygen contact and ROS diffusion. Therefore, the ROS yield gradually increases, promoting the killing rate of bacteria.

[0157] When the molecular weight of the AIE functional polymer is 3000 Da, the polymer chain length is moderate and has a certain entanglement ability, which may form nano-aggregates of ideal size. There are enough intra-chain AIE units to interact (enhancing light absorption) and form a good interpenetrating or embedded structure with the PU microdomain, giving it a strong aggregation restriction effect. At this time, the reactive oxygen species yield is the highest and the killing effect on bacteria is the greatest.

[0158] When the molecular weight of AIE functional polymers exceeds 3000 Da, the excessively long polymer chains result in strong entanglement and restricted chain segment movement, leading to poorer compatibility with polyurethane (PU). This tends to cause more pronounced phase separation, forming large self-aggregates of the AIE functional polymers. Excessive stacking of AIE units within these aggregates can lead to ACQ effects and triplet-triplet annihilation, reducing ISC efficiency and ROS quantum yield. Large aggregates also hinder internal oxygen supply, further decreasing ROS yield. Simultaneously, larger phase regions can cause surface inhomogeneities, affecting bacterial contact and resulting in low antibacterial rates.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An antibacterial photocurable resin composition, characterized in that, The raw materials include the following parts by weight: 35-65 parts of polyurethane copolymer, 30-60 parts of reactive diluent monomer, 0.1-2.0 parts of AIE functional polymer and 1-6 parts of photoinitiator; The AIE functional polymer contains polymerizable groups; the number average molecular weight of the AIE functional polymer is 1000-5000 Da; the raw materials for preparing the polyurethane copolymer include isocyanate and diol, the diol including cashew nut glycol, and the cashew nut glycol accounting for 20-80% of the molar percentage of the diol; The preparation method of the AIE functional polymer includes the following steps: S1. Compound 1 was prepared by coupling 4-bromoaniline with p-iodoanisole; the molar ratio of 4-bromoaniline to p-iodoanisole was 1:(1-1.5). S2. Compound 1 is demethylated to obtain compound 2; S3. Compound 2 and 5-aldehyde-2-thiopheneboronic acid were subjected to a Suzuki-Miyaura reaction to prepare compound 3; S4. Compound 3 is reacted with the first acrylate compound in a Williamson reaction to form an AIE monomer with a triphenylamine-based structure containing acrylate double bonds. S5. The obtained AIE monomer is photopolymerized with a second acrylate compound to obtain AIE functional polymers with different molecular weights. Wherein, the first acrylate compound is selected from one or more of ethyl isocyanate, allyl isocyanate, and isocyanoethyl methacrylate; the second acrylate compound is selected from one or more of methyl acrylate, methyl methacrylate, octyl acrylate, and isobornyl acrylate. A functional monomer with polymerizable double bonds is introduced during the synthesis stage of the polyurethane copolymer; the functional monomer is selected from one or more of acrylates or methacrylates; the molar amount of the functional monomer is 0.5-2% of the molar amount of the isocyanate.

2. The antibacterial photocurable resin composition according to claim 1, characterized in that, The raw materials for preparing the AIE functional polymer, by weight, include: 80-120 parts of 4-bromoaniline, 100-150 parts of p-iodoanisole, 250-300 parts of BBr3, 75-100 parts of 5-aldehyde-2-thiopheneboronic acid, 25-40 parts of the first acrylate compound, and 10-20 parts of the second acrylate compound.

3. The antibacterial photocurable resin composition according to claim 1, characterized in that, The cashew phenol diol accounts for 40-60% of the total diol.

4. The antibacterial photocurable resin composition according to claim 1 or 3, characterized in that, The diol also includes polycaprolactone diol, wherein the number average molecular weight of the polycaprolactone diol is 1000-5000 Da.

5. The antibacterial photocurable resin composition according to claim 1, characterized in that, The molar ratio of the isocyanate to the diol is (1-1.1):

1.

6. The antibacterial photocurable resin composition according to claim 1, characterized in that, The reactive diluent monomer is selected from one or more of hydroxyethyl methacrylate, triethylene glycol dimethacrylate, bisphenol A dimethacrylate, and urethane dimethacrylate; And / or, the photoinitiator is selected from one or more of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, camphorquinone, 2-hydroxy-2-methyl-1-phenylpropanone, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

7. A method for preparing the antibacterial photocurable resin composition according to any one of claims 1-6, characterized in that, include: The polyurethane copolymer, reactive diluent monomer, AIE functional polymer and photoinitiator were reacted at 50-60℃ under light-protected conditions for 1-3 hours.

8. The use of the antibacterial photocurable resin composition according to any one of claims 1-6 in 3D printed dental molds.

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