High-refractive-index sulfur-containing polymer dispersants, their preparation, applications, and resulting dispersions, coatings, and devices.

Abstract

This invention relates to the field of optical-grade functional materials, specifically to high-refractive-index sulfur-containing polymer dispersants, their preparation, application, and the resulting dispersions, coatings, and devices. The high-refractive-index sulfur-containing polymer dispersant is a polymer having the structure of Formula 1(). In high-refractive-index inorganic particle dispersion systems, the dispersant of this invention can reduce coating haze by more than 20%, while simultaneously increasing the refractive index of the nano-dispersion system by 0.06~0.15, significantly outperforming existing commercially available dispersant products.

Description

Technical Field

[0001] This invention relates to the field of optical-grade functional materials, and more specifically to the technical field of high-refractive-index sulfur-containing polymer dispersants. Background Technology

[0002] With the deep integration of microelectronics technology and optical display, the demand for high-refractive-index (HRIPs) optical materials is experiencing explosive growth in cutting-edge fields such as augmented reality (AR), virtual reality (VR), CMOS image sensors, and micro-light-emitting diodes (Micro-LEDs). To achieve thinner, wider-angle, and higher light extraction efficiency in optical devices, optical coating materials are required to maintain high visible light transparency while possessing extremely high intrinsic refractive index (typically requiring n...). d ≥1.70). Currently, the mainstream strategy for preparing high refractive index materials is to use inorganic nanoparticles with extremely high intrinsic refractive indices (such as zirconium dioxide ZrO2, n... d ≈ 2.1; Titanium dioxide (TiO2, n ≈ 2.5-2.7) is filled into the organic resin matrix. However, high-refractive-index nanoparticles have a huge specific surface area and high surface energy, making them prone to spontaneous aggregation and sedimentation in organic systems. This aggregation not only leads to an increase in particle size and induces severe Rayleigh scattering, but also significantly reduces the transparency of the film and increases haze. To solve the dispersion stability problem, existing technologies usually require the introduction of a dispersant accounting for 5%-30% of the particle mass. However, the framework of existing traditional dispersants is mostly composed of C, H, and O elements with low atomic polarizability, and the intrinsic refractive index is extremely low (n ≈ 2.1; Titanium dioxide (TiO2, n ≈ 2.5-2.7). d (Only 1.40-1.50). When introduced into a high-filler system at a high proportion, it produces a severe "refractive index dilution effect," making it difficult for the overall refractive index of the composite system to reach the expected level. Furthermore, the development of high-refractive-index sulfur-containing polymer dispersants is often accompanied by severe color shift (yellowing or blackening) and decreased transmittance, failing to meet the stringent requirements of precision optical coatings for hue and high transmittance. In addition, directly blending existing dispersants with inorganic nanoparticles can cause serious interfacial compatibility problems, leading to particle agglomeration, product fogging, and a sharp drop in transmittance. Summary of the Invention

[0003] To overcome the problem that traditional dispersants have low intrinsic refractive index and produce a "refractive index dilution effect" in highly filled nano-dispersions, resulting in a decrease in the overall refractive index, this invention provides a high refractive index sulfur-containing polymer dispersant. The aim is to provide a dispersant that takes into account both excellent intrinsic refractive index and can improve interfacial compatibility with inorganic particles.

[0004] The second objective of this invention is to provide a method for preparing and applying the aforementioned high-refractive-index sulfur-containing polymer dispersant.

[0005] A third objective of this invention is to provide dispersions, coatings, and devices comprising the aforementioned high-refractive-index sulfur-containing polymer dispersant.

[0006] The key factors affecting the refractive index of high-refractive-index coatings are mainly twofold: the intrinsic refractive index of the dispersant and the interfacial compatibility between the dispersant and the inorganic material. Both must be considered synergistically to achieve the desired effect—even if the dispersant possesses excellent intrinsic refractive properties, poor compatibility with the inorganic material will still significantly reduce the refractive index performance of the high-refractive-index coating. However, existing dispersants struggle to simultaneously meet the dual requirements of intrinsic high refractive index and targeted compatibility with inorganic materials. To address this issue, this invention proposes the following improvement:

[0007] High-refractive-index sulfur-containing polymer dispersants are polymers with the structure of Formula 1:

[0008] Formula 1

[0009] In Equation 1, R1, R3, and R5 are H or CH3;

[0010] R2 is C1~C 18 Alkyl or substituted alkyl, cycloalkyl, ether chain or aryl;

[0011] R4 is a substituent containing at least one active substituent of a phosphate ester group, a carboxyl group, or a siloxane;

[0012] R6 is a structural unit containing at least one of an aromatic ring, a thioether bond, a sulfur atom, or a halogen with high electronic polarizability / high molar refractivity.

[0013] S x These are polysulfide compound segments (x = 1 ~ 8);

[0014] Y is either O or S;

[0015] The molar ratio of n1:n2:n3 is 1~30:1~30:10~85.

[0016] This invention provides a novel ternary polymer dispersant that disperses polysulfide compound segments (S... xBy introducing a polymer backbone and simultaneously incorporating high-refractive-index functional units and multi-mode anchoring units (R2, R4, R6) into the side chains, a synergistic effect of increased refractive index, enhanced interfacial adsorption, and improved dispersion stability is achieved. This synergistic effect is not a simple superposition of the properties of each structural unit, but rather stems from the mutually reinforcing interaction between the conformational flexibility of the polysulfide backbone, the coordination activity of sulfur atoms, and the polarizability of the high-refractive-index side groups—an effect that is difficult for those skilled in the art to anticipate. In particular, the dispersant of this invention, in a high-refractive-index inorganic particle (n ≥ 1.8) dispersion system, can reduce coating haze by more than 20% while maintaining a refractive index n ≥ 1.60, significantly outperforming existing commercial dispersant products.

[0017] In Formula 1, R1, R3, and R5 are H or CH3, preferably R1, R3, and R5 are CH3 groups;

[0018] R2 is C1~C 18 alkyl or polyether chains;

[0019] R4 is a substituted alkyl group containing a phosphate ester group, a substituted phosphate ester group, or a substituted alkyl group containing a silane segment;

[0020] R6 is a group containing at least one of an aromatic ring, a thioether bond, a sulfur atom, or a halogen; preferably, R6 is selected from the following groups: phenyl, biphenyl, naphthyl, fluorenyl, carbazolyl, phenylthioyl (–S–C6H5), bromophenyl, dibromophenyl, thiophene, or phenylthioalkyl (–R'–S–Ph).

[0021] More preferably, R6 is an aromatic substituent containing a sulfide bond or a bromine-containing aromatic group, wherein the refractive index n of the monomer corresponding to R6 is ≥ 1.55;

[0022] S x For polysulfide compound segments, x = 2~4;

[0023] Further details on the characteristics of the polymer:

[0024] In Equation 1, the molar ratio of n1:n2:n3 is 4-6:4-10:20-40;

[0025] In Formula 1, the mass fraction of sulfur in the polymer dispersant is 5% to 50%, preferably 20% to 35%;

[0026] In Formula 1, the refractive index n of the polymer dispersant film is ≥ 1.55, preferably n ≥ 1.60 (589 nm, 25°C).

[0027] In Formula 1, the number-average molecular weight (M) of the polymer dispersant is... nThe concentration is 2,000–100,000 g / mol, preferably 3,000–10,000 g / mol;

[0028] This invention also provides a method for preparing a high-refractive-index sulfur-containing polymer dispersant, which involves mixing a composite monomer, sulfur, and an initiator and then polymerizing the mixture to obtain the desired dispersant.

[0029] The composite monomer includes monomer of formula 2 and monomer of formula 3, and may selectively include monomer of formula 4;

[0030] Formula 2

[0031] Formula 3

[0032] Formula 4

[0033] The selection ranges of R1~R6 and Y in Equations 2~3 are the same as those in Equation 1.

[0034] This invention innovatively uses the aforementioned composite monomer, sulfur, and initiator for polymerization, thereby preparing a dispersant that combines excellent intrinsic refractive index with interfacial compatibility with inorganic particles, which is beneficial for enhancing the comprehensive mechanical and refractive properties of subsequent inorganic-organic high-refractive-index coatings.

[0035] In this invention, the monomer of formula 2 includes at least one of the following compounds;

[0036] .

[0037] In this invention, the monomer of formula 3 includes at least one of the following compounds;

[0038] .

[0039] R3 in formulas 3a and 3b is a methyl group.

[0040] In this invention, the monomer of Formula 4 includes at least one of the following compounds.

[0041]

[0042] In formulas 4a and 5a, R5 is a methyl group.

[0043] In this invention, the molar ratio of Formula 2: Formula 3: Formula 4 in the composite monomer is 1-30: 1-30: 10-85; preferably 4-6: 4-10: 20-40.

[0044] In this invention, the polymerization method can be free radical polymerization or anionic polymerization.

[0045] Preferably, the initiator is a compound having the structure of Formula 5;

[0046] Formula 5;

[0047] In Formula 5, R7 is H, an alkyl group of C1 to C4, a benzyl group, a phenylthio group, or a mercapto-substituted phenylthio group;

[0048] In this invention, the sulfur is S8.

[0049] Preferably, the molar ratio of the composite monomer to sulfur is 1:0.5 to 1:20; more preferably, it is 1:1 to 6; the amount of initiator is 3 to 15 mol% of the molar amount of sulfur; and more preferably, it can be 5 to 10 mol%.

[0050] Preferably, the solvent used in the polymerization process is a hydrophobic solvent; more preferably, it can be at least one of N,N-dimethylformamide (DMF), N,N-diethylformamide (DMAc), and dimethyl sulfoxide (DMSO).

[0051] Preferably, the polymerization temperature is 20~80°C;

[0052] Preferably, the polymerization time is 18-30 h;

[0053] In this invention, the refractive index can be adjusted by controlling the ratio of the composite monomer to sulfur. For example, by adjusting the monomer:S8 feeding ratio (1:0.5~1:10), the sulfur content of the dispersant can be controlled within the range of 5~50 wt%, thereby adjusting the intrinsic refractive index within the range of 1.50~1.75; increasing the amount of S8 increases the sulfur content from about 18 wt% to about 40 wt%, and the refractive index increases from 1.59 to 1.65.

[0054] The present invention also provides an application of the aforementioned high refractive index sulfur-containing polymer dispersant, which is combined with inorganic materials to prepare organic-inorganic composite high refractive index dispersions and / or coatings.

[0055] The present invention also provides an organic-inorganic composite high refractive index dispersion, comprising a dispersant, a solvent and an inorganic material, wherein the dispersant is the high refractive index sulfur-containing polymer dispersant described above;

[0056] Preferably, the solvent includes at least one of propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol methyl ether acetate, methyl ethyl ketone, or tetrahydrofuran;

[0057] Preferably, the inorganic material includes at least one of zirconium dioxide (ZrO2), titanium dioxide (TiO2), or zinc sulfide (ZnS);

[0058] Preferably, in the organic-inorganic composite high-refractive-index dispersion, the content of inorganic material is 10-60 wt.%; more preferably, it is 25-35 wt.%. The dispersant can be 1-20 wt.% of the weight of the inorganic material; more preferably, it is 5-15 wt.%.

[0059] The preparation method of the dispersion includes: washing inorganic nanoparticles 2-3 times by centrifugation with an organic solvent, adding a high-refractive-index sulfur-containing polymer dispersant (5-20 wt% of the nanoparticle mass), stirring and reacting at room temperature to 150°C for 8-24 h to allow the dispersant to fully chemically bond to the particle surface, filtering through a 0.22 μm filter membrane, and then concentrating by rotary evaporation to obtain a dispersion with a solid content of 30-50 wt%; the refractive index n of the cured film prepared from the dispersion is... d Compared to using traditional dispersants (n) at the same nanoparticle loading amount d The cured film obtained by (e.g., 1.40~1.50) has an improvement of 0.06~0.15, visible light transmittance >91%, and haze <0.5%.

[0060] The present invention also provides applications of the aforementioned dispersion for preparing high refractive index optical coatings, augmented reality (AR) / virtual reality (VR) waveguide coatings, CMOS image sensor encapsulation coatings, or UV-curable nanoimprint adhesives.

[0061] The present invention also provides an organic-inorganic composite high refractive index coating comprising a dispersant and an inorganic material, wherein the dispersant is the high refractive index sulfur-containing polymer dispersant described in the present invention;

[0062] Preferably, the coating is obtained by drying an organic-inorganic composite high-refractive-index dispersion.

[0063] The present invention also provides a high refractive index device, the surface of which is coated with the organic-inorganic composite high refractive index coating described in the present invention;

[0064] Preferably, the high-refractive-index device is a high-refractive-index optical device, an augmented reality (AR) / virtual reality (VR) waveguide coating device, a CMOS image sensor, or an ultraviolet-curable nanoimprint adhesive.

[0065] Beneficial effects:

[0066] 1. Adjustable and significantly improved refractive index of the dispersant: The intrinsic refractive index of the dispersant described in this invention can be adjusted by using elemental sulfur and high refractive index units, and its refractive index is adjustable in the range of 1.50~1.75, which is significantly improved compared to traditional carbon-oxygen skeleton dispersants (n... d Compared to (1.40~1.50), the refractive index is increased by 0.10~0.35.

[0067] 2. Reduce the dilution effect of the dispersant's refractive index: When the dispersant described in this invention is combined with high refractive index nanoparticles, under the same particle filling amount, the overall refractive index of the nano-dispersion is increased by 0.06~0.15 compared with the traditional system due to the high refractive index of the dispersant itself, effectively eliminating the dilution effect of the dispersant on the overall refractive index in the nanocomposite system.

[0068] 3. Inorganic material interface compatibility: The dispersant of this invention has selective chemical interaction with the surface of inorganic nanoparticles, which can improve the interface compatibility of inorganic materials, thereby improving the stability and performance of the dispersion and coating. For example, the dispersion of this invention achieves ultra-long storage stability of more than 6 months at room temperature.

[0069] 4. Excellent optical quality: This invention controls the sulfur content within the optimal range through a mild synthesis process, so that while the refractive index of the sulfur-containing dispersant is improved, the light transmittance remains >92% and the haze <0.2%, effectively suppressing the yellowing problem common in high sulfur-containing systems. Attached Figure Description

[0070] Figure 1 The image shows the 1H NMR spectrum of the polymer dispersant (Si-S18wt%) in Example 1-1.

[0071] Figure 2 The Fourier transform infrared absorption spectrum (FTIR) of the polymer dispersant (Si-S18wt%) in Example 1-1 is shown.

[0072] Figure 3 The refractive index curve of the polymer dispersant (Si-S18wt%) in Example 1-1 is shown.

[0073] Figure 4 The refractive index curves are for the polymer dispersant (Si-S34wt%) in Examples 1-4.

[0074] Figure 5 The images show the nano-dispersions of Examples 2-1, 2-2, 2-3, and 2-4.

[0075] Figure 6 This is a transmission electron microscope (TEM) image of the zirconium dioxide nanodispersion in Example 2-1.

[0076] Figure 7 The images are transmission electron microscope (TEM) images of titanium dioxide nanoparticles in Examples 2-4.

[0077] Figure 8 The refractive index diagram of the zirconium dioxide nano-dispersion coating in Example 2-1 is shown. Detailed Implementation

[0078] Test methods

[0079] 1) Dispersion appearance test:

[0080] The visual inspection method is used. Under natural light, place the sample to be tested in a transparent glass bottle and observe its color, transparency, and whether there is any sediment or layering. If it is a clear and transparent liquid, it is judged to be "transparent"; if it is a translucent liquid that allows light to pass through, it is judged to be "translucent"; if it is white, cloudy, opaque, or has obvious sediment, it is judged to be "white".

[0081] 2) Molecular weight test

[0082] The molecular weight and polydispersity index (PDI) of the dispersant were determined using a Shimadzu Prominence LC-20A system equipped with a Prominence RID-20A differential refractive index detector and a Prominence SPD-20A UV-Vis detector (detection wavelength 250 nm). Gel permeation chromatography (GPC) was performed at 20 °C with tetrahydrofuran (THF) or water as the mobile phase, and polymethyl methacrylate (PMMA) as the calibration standard.

[0083] 3) Refractive index testing

[0084] The refractive index of UV-curable coatings was tested according to GB / T 6488-2008 standard. The refractive index of the UV-curable coatings was measured using an Abbemat 300 refractometer at 20℃.

[0085] 4) Viscosity test

[0086] The viscosity of high-refractive-index nano-dispersions was tested using a Brookfield rotational viscometer. The viscometer model was RV-SSR-H, and it was compatible with an ultra-low viscosity adapter (ULR).

[0087] 5) Transmittance test

[0088] The transmittance of the optical film was tested according to GB / T 2410-2008 standard. The transmittance of the optical film prepared on the glass substrate was tested in the range of 400nm~700nm using a UV-vis spectrophotometer.

[0089] 6) Haze test

[0090] A colorimeter was used to measure the cured optical thin film and calculate the ratio of scattered light flux to transmitted light flux. The colorimeter model was TS8520.

[0091] 7) Dispersion stability test

[0092] Seal the sample and store it at room temperature (25°C). Observe it periodically to see if gelation, layering, or precipitation occurs. Record the longest time that the sample remains clear and transparent without precipitation.

[0093] The following examples are examples of possible solutions:

[0094] Formula 2 monomers are typically illustrated using Formula 2A as an example:

[0095] Formula 2A;

[0096] The molecular weight of Formula 2A is 400.

[0097] Formula 3 uses Formula 3a and Formula 3b as typical examples of monomers:

[0098] Equation 3a;

[0099] Equation 3b;

[0100] Formula 3c;

[0101] Formula 4 monomers are typically illustrated using Formula 4a as an example:

[0102] Equation 4a;

[0103] Equation 4b.

[0104] I. Dispersant Preparation

[0105] Example 1-1: Siloxane-anchored high refractive index dispersant (Si-S 18wt%)

[0106] Procedure: In a dry 100 mL Schlenk flask, add formula 4a (30 mmol), formula 3a (5 mmol), formula 2A (5 mmol), and elemental sulfur S8 (2.00 g, equivalent to 60 mmol sulfur atoms) sequentially, and dissolve completely in 20 mL of anhydrous DMF. Add initiator PhSNa (0.35 g, 5 mol% molar ratio to S8). Perform three cycles of "freeze-thaw-vacuum-argon purging" on the system. Under argon protection, stir magnetically at 25°C for 24 h, and the color of the reaction solution changes from pale yellow to deep red. Filter to remove a small amount of unreacted S8 solid particles, slowly pour the filtrate into cold diethyl ether (300 mL, 0°C) to precipitate, filter, wash twice with diethyl ether, and vacuum dry at 40°C for 24 h to obtain a white powder product. Obtain white powdered Si-S18wt%. Mn = 2.5 kg / mol, S content 19.1 wt%, n d = 1.58@589 nm.

[0107] Examples 1-2: Phosphate ester anchored high refractive index dispersant (P-S 18wt%)

[0108] In a dry 100 mL Schlenk flask, 30 mmol of formula 4a, 5 mmol of formula 3b, 5 mmol of formula 2A, and 2.00 g of elemental sulfur S8 (equivalent to 60 mmol sulfur atoms) were added sequentially, followed by 20 mL of anhydrous DMF to dissolve completely. PhSNa (0.35 g, 5 mol% molar ratio to S8) was added as an initiator. The system was subjected to three cycles of freeze-thaw, vacuuming, and argon purging to remove oxygen. Under argon protection, the mixture was magnetically stirred at 25°C for 24 h, during which the color of the reaction solution changed from pale yellow to deep red. A small amount of unreacted S8 solid particles was then removed by filtration. The filtrate was slowly poured into cold diethyl ether, causing a solid precipitate to form. This precipitate was filtered, washed twice with diethyl ether, and dried under vacuum at 40°C for 24 h to obtain a white powder, P-S18wt%. n = 3.2 kg / mol, S content is 18.2 wt%, n d = 1.58@589 nm.

[0109] Examples 1-3: High-sulfur content siloxane-anchored high-refractive-index dispersants (Si-S 25wt%)

[0110] In a dry 100 mL Schlenk flask, a monomer mixture (Formula 4a 30 mmol, Formula 3a 5 mmol, Formula 2A 5 mmol) was added, followed by elemental sulfur S8 (3.5 g, equivalent to approximately 110 mmol of sulfur atoms), bringing the total monomer to sulfur a molar ratio of 1:2.75. The initiator PhSNa (5 mol%) was then added. The remaining steps and purification process were the same as in Example 1. The resulting product was a solid resin, M n = 2.8 kg / mol, S content = 24.6 wt%, refractive index n d = 1.60 @589 nm.

[0111] Examples 1-4: High-sulfur content siloxane-anchored high-refractive-index dispersants (Si-S 34wt%)

[0112] In a dry 100 mL Schlenk flask, a monomer mixture (Formula 4a 30 mmol, Formula 3a 5 mmol, Formula 2A 5 mmol) was added, followed by elemental sulfur S8 (7.05 g, equivalent to approximately 220 mmol of sulfur atoms), bringing the total monomer to sulfur a molar ratio of 1:5.5. The initiator PhSNa (molar ratio 5 mol%) was then added. The remaining steps and purification process were the same as in Example 1. The resulting product was a pale yellow, transparent solid resin. n = 2.9 kg / mol, S content = 36.5 wt%, refractive index n d = 1.62 @589 nm.

[0113] Examples 1-5: High anchoring density dispersant (Si-S18wt%-HiAnchor)

[0114] In a dry 100 mL Schlenk flask, add formula 4a (30 mmol), formula 3a (7.5 mmol), formula 2A (5 mmol), and elemental sulfur S8 (2.00 g, equivalent to 60 mmol sulfur atoms) sequentially, and dissolve completely in 20 mL of anhydrous DMF. Add initiator PhSNa (0.35 g, 5 mol% molar ratio to S8). The remaining steps and purification process are the same as in Example 1-1. The refractive index n of the obtained product is... d = 1.56 @589 nm.

[0115] In this embodiment, while maintaining the high refractive index framework and sulfur content of Formula 4a basically unchanged, the amount of anchoring monomer Formula 3a is increased to 7.5 mmol (1.5 times that of Example 1-1), which is expected to further improve the dispersion stability of nanoparticles; however, the intrinsic refractive index of the dispersant decreases from 1.58 to 1.56.

[0116] Examples 1-6: Bifunctional acrylic siloxane-anchored high refractive index dispersant (Spd-Si-S 18wt%)

[0117] This embodiment uses a bifunctional monomeric 4b(n) d_ ≈ 1.65) was used as the high refractive index unit. In a dry 100 mL Schlenk flask, formula 4b (30 mmol), formula 3a (5 mmol), formula 2A (5 mmol), and elemental sulfur S8 (2.00 g, equivalent to 60 mmol sulfur atoms) were added sequentially, followed by 20 mL of anhydrous DMF to dissolve completely. Initiator PhSNa (0.35 g, 5 mol% molar ratio to S8) was added. The remaining steps and purification process were the same as in Example 1-1, yielding powdered Spd-Si-S18wt%, with an S content of 18.7 wt% and n d = 1.60@589 nm.

[0118] Comparative Example 1-1 (S18wt%)

[0119] Compared with Example 1-1, the only difference is that monomer 3a is omitted; the amounts of the remaining monomers and the operating steps are exactly the same as in Example 1-1, yielding S18wt% resin, M n = 2.4 kg / mol, S content = 20.1 wt%, n d = 1.57@589 nm.

[0120] Comparative Examples 1-2: (C-S 18wt%)

[0121] Compared to Examples 1-2, Formula 3b was replaced with Formula 3c (0.36 g, 5 mmol), while the amounts of other monomers and the operating procedures were exactly the same as in Examples 1-1, yielding C-S18 wt% resin. Characterization results: M n = 4.3 kg / mol, S content = 17.8 wt%, n d = 1.58@589 nm.

[0122] Table 1. High Refractive Index Dispersants

[0123]

[0124] II. Preparation of Organic-Inorganic Dispersions

[0125] Example 2-1:

[0126] Two grams of zirconia powder (original particle size 10-15 nm) were centrifuged and washed three times with an organic solvent (such as propylene glycol monomethyl ether) to remove surface impurities and weak adsorbates. The washed wet cake was transferred to an Erlenmeyer flask, and 22 grams of the organic solvent and 0.2 grams of dispersant (high refractive index sulfur-containing dispersant prepared in Example 1-1) were added. The mixture was reacted at 50±5℃ for 12 hours under stirring to allow the dispersant to be fully adsorbed or chemically bonded to the surface of the zirconia nanoparticles, resulting in a surface-modified primary dispersion of zirconia. The obtained primary dispersion was filtered through a 0.22-micron microporous membrane to remove a small amount of agglomerated particles or impurities. Subsequently, the filtrate was concentrated under reduced pressure by rotary evaporation to finally obtain a high refractive index sulfur-containing dispersant-modified zirconia nanoparticle dispersion (test results are shown in Table 2).

[0127] Example 2-2:

[0128] Compared with Example 2-1, the only difference is that the dispersant prepared in Example 1-2 is used to replace the dispersant in Example 2-1, and the preparation process of Example 2-1 is repeated. The test results of the final dispersion are shown in Table 2.

[0129] Examples 2-3:

[0130] Compared with Example 2-1, the only difference is that the dispersant prepared in Example 1-4 is used to replace the dispersant in Example 2-1, and the preparation process of Example 2-1 is repeated. The test results of the final dispersion are shown in Table 2.

[0131] Examples 2-4:

[0132] Compared with Example 2-1, the only difference is that titanium dioxide powder (anatase type, original particle size of 10-15 nm) is used instead of ZrO2 as filler. All other operations and parameters are the same as in Example 2-1. The test results of the final dispersion are shown in Table 2.

[0133] Comparative Example 2-1:

[0134] Compared to Example 2-1, the only difference is that the dispersant is replaced with commercially available KH570 (n d = 1.43), other operations and parameters are the same as in Example 2-1, and the test results of the final dispersion are shown in Table 2.

[0135] Comparative Example 2-2:

[0136] Compared to Example 2-1, the only difference is that the dispersant is replaced with a commercially available phosphate ester dispersant (DISPERBYK-111, n d = 1.45), other operations and parameters are the same as in Example 2-1, and the test results of the final dispersion are shown in Table 2.

[0137] Comparative Examples 2-3:

[0138] Compared with Example 2-1, the only difference is that the dispersant is replaced with the dispersant of Comparative Example 1-1. All other operations and parameters are the same as in Example 2-1. The test results of the final dispersion are shown in Table 2.

[0139] Comparative Examples 2-4:

[0140] Compared with Example 2-1, the only difference is that the dispersant was replaced with the dispersant prepared in Comparative Example 1-2. All other operations and parameters are the same as in Example 2-1. The test results of the final dispersion are shown in Table 2.

[0141] Table 2. High refractive index nanodispersions

[0142]

[0143] Analysis of test results for each embodiment and comparative example

[0144] 1) Example 1-1 (sulfur content 19.1 wt%, n d = 1.58), Examples 1-3 (sulfur content 24.6 wt%, n d =1.60) and Examples 1-4 (sulfur content 36.5 wt%, n d = 1.62) indicates that, within the sulfur content range of 19–37 wt%, the intrinsic refractive index increases by approximately 0.02 for every 8 wt% increase in sulfur content, demonstrating a good linear correlation. In contrast, the intrinsic refractive index of conventional commercial dispersants is only 1.40–1.50, while the dispersant of this invention achieves a refractive index increase of 0.08–0.22 within the same sulfur content range.

[0145] 2) Comparing Example 1-1, Example 1-2 and Comparative Example 1-2, the sulfur content of the three is similar and the refractive index is basically the same, indicating that the type of anchoring group has little effect on the intrinsic refractive index of the dispersant, and the refractive index is mainly determined by the contribution of polysulfide segments.

[0146] 3) Comparing Examples 1-1 and 1-4, the transmittance decreased slightly from >93.3% to >90.0%, and the haze increased from 0.10% to 0.23%, indicating that the increase in S content will cause the system to yellow and scatter. However, all examples remain within the acceptable range for optical applications (transmittance >90%, haze <0.3%).

[0147] 4) The refractive index of the cured film of the dispersion prepared in Example 2-1 reached 1.81, while the refractive index of the film using a traditional low-refractive-index dispersant (n) was significantly lower. dComparative Example 2-2 (≈ 1.45) has a refractive index of only 1.69 with similar solid content, representing an absolute increase of 0.12 and a relative increase of about 7.1%, demonstrating the synergistic enhancement effect of high refractive index sulfur-containing dispersants on the refractive index of high-refractive-index nano-dispersions.

[0148] 5) Comparing Example 2-1 (siloxane-based anchoring, Si-S 18wt%) and Example 2-2 (phosphate ester-based anchoring, P-S 18wt%), both ZrO2 dispersions exhibited a white and transparent appearance, with film refractive indices of 1.81 and 1.80, respectively, and storage stability of ≥180 days, showing comparable performance. However, Comparative Example 2-4 (carboxylic acid-based anchoring, C-S 18wt%) failed to form a stable ZrO2 dispersion under identical dispersion process conditions, directly producing a white precipitate, and its refractive index, transmittance, and haze could not be measured. This indicates the high selectivity of the anchoring groups to the surface chemical properties of inorganic particles. The coordination bond energy of the carboxylic acid group on the ZrO2 surface (approximately 40 kJ / mol) is lower than that of the siloxane group (covalent bonding) and the phosphate ester group (60~120 kJ / mol), which is insufficient to maintain stable dispersion in high specific surface area ZrO2 systems. This principle also provides an important basis for the targeted design of the dispersant in this invention.

[0149] 6) In Examples 2-3 (dispersant: Si-S 34wt%, n = 1.62), compared to Example 2-2 (dispersant: P-S 18wt%, n = 1.58), the refractive index of the dried coating further increased from 1.80 to 1.83, an absolute increase of 0.03. Both examples are significantly higher than the 1.69 refractive index of the coating in Comparative Example 2-2 (dispersant: BYK-111, n = 1.45). This indicates that the increase in the intrinsic refractive index of the dispersant (from 1.45 to 1.62) can directly lead to a corresponding increase in the refractive index of the cured film of the nano-dispersion (from 1.70 to 1.83), reflecting the positive transmission effect between the refractive index of the dispersant and the refractive index of the composite system. The ZrO2 dispersion prepared with the dispersant represented by Si-S 18wt% achieved an ultra-long storage stability of ≥180 days at room temperature, while the stability period of the traditional commercial dispersant (BYK-111) is only about 14 days, an improvement of more than 12 times.

[0150] 7) Comparative Examples 2-3, using sulfur-containing polymers without anchoring groups, produced nano-dispersions that directly showed white precipitates at the same solid content (30.5 wt%), making it impossible to measure refractive index, transmittance, and haze; the dispersion was completely ineffective. This indicates that the introduction of strong anchoring groups is a necessary condition for achieving stable dispersion of nanoparticles with sulfur-containing high refractive index dispersants.

[0151] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A high-refractive-index sulfur-containing polymer dispersant, characterized in that: For polymers having the structure of Formula 1: Formula 1 In Equation 1, R1, R3, and R5 are H or CH3; R2 is C1~C 18 Alkyl or substituted alkyl, cycloalkyl, ether chain or aryl; R4 is a substituent containing at least one active substituent of a phosphate ester group, a carboxyl group, or a siloxane; R6 is a structural unit containing at least one of an aromatic ring, a thioether bond, a sulfur atom, or a halogen with high electronic polarizability / high molar refractivity. S x These are polysulfide compound segments (x = 1 ~ 8); Y is either O or S; The molar ratio of n1:n2:n3 is 1~30:1~30:10~85.

2. The high refractive index sulfur-containing polymer dispersant as described in claim 1, characterized in that: In Equation 1, R2 represents C1~C 18 alkyl or polyether chains; R4 is a phosphate ester group, a substituted phosphate ester group, or a substituted alkyl group with a silane segment; R6 is phenyl, biphenyl, naphthyl, fluorenyl, carbazolyl, phenylthio (–S–C6H5), bromophenyl, dibromophenyl, thiophene, or phenylthioalkyl; S x It consists of polysulfide compound segments, x = 2~4.

3. The high refractive index sulfur-containing polymer dispersant as described in claim 1 or 2, characterized in that: In Equation 1, the molar ratio of n1:n2:n3 is 4-6:4-10:20-40; In Formula 1, the mass fraction of sulfur in the polymer dispersant is 5% to 50%, preferably 20% to 35%; In Formula 1, the refractive index n of the polymer dispersant film is ≥ 1.55, preferably n ≥ 1.60 (589 nm, 25°C). In Formula 1, the number-average molecular weight (Mn) of the polymer dispersant is 2,000 to 100,000 g / mol, preferably 3,000 to 10,000 g / mol.

4. A method for preparing a high-refractive-index sulfur-containing polymer dispersant, characterized in that: The composite monomer, sulfur, and initiator are mixed and polymerized to obtain the product. The composite monomer includes monomer of formula 2 and monomer of formula 3, and may selectively include monomer of formula 4; Formula 2 Formula 3 Formula 4 The selection ranges of R1~R6 and Y in Equations 2~3 are the same as those in Equation 1.

5. The method for preparing the high refractive index sulfur-containing polymer dispersant as described in claim 1, characterized in that: The monomer of Formula 2 includes at least one of the following compounds; ； Preferably, the monomer of formula 3 includes at least one of the following compounds; ； Preferably, the monomer of Formula 4 is a compound of at least one of the following; 。 6. The method for preparing the high refractive index sulfur-containing polymer dispersant as described in claim 4, characterized in that: In the composite monomer, the molar ratio of Formula 2: Formula 3: Formula 4 is 1-30: 1-30: 10-85; preferably 4-6: 4-10: 20-40. Preferably, the initiator is a compound having the structure of Formula 5; Formula 5; In Formula 5, R7 is H, an alkyl group of C1 to C4, a benzyl group, a phenylthio group, or a mercapto-substituted phenylthio group; Preferably, the molar ratio of the composite monomer to sulfur is 1:0.5 to 1:20; more preferably, it is 1:1 to 6; the amount of initiator is 3 to 15 mol% of the molar amount of sulfur. Preferably, the solvent used in the polymerization process is a hydrophobic solvent; Preferably, the polymerization temperature is 20~80°C; Preferably, the polymerization time is 18-30 h.

7. The application of a high refractive index sulfur-containing polymer dispersant according to any one of claims 1 to 3 or a high refractive index sulfur-containing polymer dispersant prepared by the preparation method according to any one of claims 4 to 6, characterized in that: By combining it with inorganic materials, organic-inorganic composite high-refractive-index dispersions and / or coatings can be prepared.

8. An organic-inorganic composite high-refractive-index dispersion, comprising a dispersant, a solvent, and an inorganic material, characterized in that, The dispersant is the high refractive index sulfur-containing polymer dispersant according to any one of claims 1 to 3 or the high refractive index sulfur-containing polymer dispersant prepared by the preparation method according to any one of claims 4 to 6; Preferably, the solvent includes at least one of propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol methyl ether acetate, methyl ethyl ketone, or tetrahydrofuran; Preferably, the inorganic material includes at least one of zirconium dioxide (ZrO2), titanium dioxide (TiO2), or zinc sulfide (ZnS); Preferably, in the organic-inorganic composite high refractive index dispersion, the content of inorganic materials is 10-60 wt.%; more preferably 25-35 wt.%; and the dispersant is 1-20 wt.% of the weight of the inorganic materials; more preferably 5-15 wt.%. Preferably, it is used to prepare high refractive index optical coatings, augmented reality (AR) / virtual reality (VR) waveguide coatings, CMOS image sensor encapsulation coatings, or UV-curable nanoimprint adhesives.

9. An organic-inorganic composite high-refractive-index coating, comprising a dispersant and an inorganic material, characterized in that, The dispersant is the high refractive index sulfur-containing polymer dispersant according to any one of claims 1 to 3 or the high refractive index sulfur-containing polymer dispersant prepared by the preparation method according to any one of claims 4 to 6; Preferably, it is obtained by drying an organic-inorganic composite high-refractive-index dispersion.

10. A high-refractive-index device, characterized in that, The surface is coated with the organic-inorganic composite high-refractive-index coating as described in claim 9; Preferably, the high-refractive-index device is a high-refractive-index optical device, an augmented reality (AR) / virtual reality (VR) waveguide coating device, a CMOS image sensor, or an ultraviolet-curable nanoimprint adhesive.

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