阅读说明：本技术 包含银纳米片的组合物 (Compositions comprising silver nanoplates ) 是由 N·A·格里戈连科 A·奥斯瓦尔德 M·里歇特 于 2020-04-23 设计创作，主要内容包括：本发明涉及包含银纳米片的组合物,其中组合物中存在的银纳米片的数量平均直径在50至150nm的范围内,其中标准偏差小于60％,且组合物中存在的银纳米片的数量平均厚度在5至30nm的范围内,其中标准偏差小于50％,其中银纳米片的平均纵横比高于2.0,且组合物中所有银纳米片的总体的最高波长吸收最大值在560至800nm的范围内。包含该组合物的涂层在透射中显示出蓝色且在反射中显示出金属黄色。(The present invention relates to a composition comprising silver nanoplates, wherein the number average diameter of the silver nanoplates present in the composition is in the range of 50 to 150nm, wherein the standard deviation is less than 60%, and the number average thickness of the silver nanoplates present in the composition is in the range of 5 to 30nm, wherein the standard deviation is less than 50%, wherein the average aspect ratio of the silver nanoplates is higher than 2.0, and the highest wavelength absorption maximum of the ensemble of all silver nanoplates in the composition is in the range of 560 to 800 nm. Coatings comprising the composition exhibit a blue color in transmission and a metallic yellow color in reflection.)

1. A composition comprising silver nanoplates, wherein the average diameter of the silver nanoplates present in the composition is in the range 50nm to 150nm, wherein the standard deviation is less than 60%, and the average thickness of the silver nanoplates present in the composition is in the range 5nm to 30nm, wherein the standard deviation is less than 50%, wherein the average aspect ratio of the silver nanoplates is higher than 2.0, and the highest wavelength absorption maximum of the ensemble of all silver nanoplates in the composition is in the range 560nm to 800nm, in particular in the range 600nm to 800 nm.

2. The composition according to claim 1, wherein the molar extinction coefficient of the silver nanoplates, measured at the highest wavelength absorption maximum of the population of all silver nanoplates in the composition, is higher than 4000L/(cm x mol)_Ag)。

3. A composition according to claim 1 or 2, wherein the silver nanoplates have a surface stabilizer on their surface of the formula:

wherein

R¹Is H, C₁-C₁₈Alkyl, phenyl, C₁-C₈Alkylphenyl or CH₂COOH；

R²、R³、R⁴、R⁵、R⁶And R⁷Independently of one another is H, C₁-C₈Alkyl or phenyl;

y is O or NR⁸；

R⁸Is H or C₁-C₈An alkyl group;

k1 is an integer in the range of 1 to 500,

k2 and k3 are independently of each other 0 or an integer in the range of 1 to 250;

k4 is 0 or 1 and,

k5 is an integer in the range of 1 to 5.

4. A composition according to any one of claims 1 to 3, wherein the silver nanoplates have a surface stabilizer, said stabilizer being a polymer or copolymer, obtained by a process comprising the steps of:

i1) in a first step at least one of the compounds has a structural elementPolymerizing one or more ethylenically unsaturated monomers in the presence of the nitroxyl ether of (a),

wherein X represents a group having at least one carbon atom and which enables a radical X. generated by X to initiate polymerization; or

i2) In a first step in at least one stable nitroxide radicalAnd polymerizing one or more ethylenically unsaturated monomers in the presence of a free radical initiator; c wherein at least one monomer used in step i1) or i2) is acrylic acid or methacrylic acid₁-C₆Alkyl or C₁-C₆A hydroxyalkyl ester; and optionally

ii) a second step comprising modifying the polymer or copolymer prepared under i1) or i2) by transesterification, amidation, hydrolysis or anhydride modification or a combination thereof.

5. A composition according to claim 3, wherein R¹Is H or C₁-C₈An alkyl group; r²、R³、R⁴、R⁵、R⁶And R⁷Independently of one another, H or CH₃(ii) a Y is O or NR⁸；R⁸Is H or C₁-C₈An alkyl group; k1 is 22 to 450; k2 and k3 are independently of each other 0 or an integer in the range of 1 to 100; k4 is 0; k5 is an integer in the range of 1 to 4.

6. A composition according to claim 5 wherein the surface stabilizer has the formulaWherein

R¹Is H or C₁-C₈An alkyl group; and

k1 is 22 to 450, in particular 22 to 150.

7. The composition according to any one of claims 1 to 6, comprising one or more stabilizers selected from the group consisting of compounds of formula (IIb) and compounds of formula (IIc):

wherein

R^21aIs a hydrogen atom, a halogen atom, C₁-C₈Alkoxy or C₁-C₈An alkyl group, a carboxyl group,

R^21bis a hydrogen atom or a compound of the formula-CHR²⁴-N(R²²)(R²³) The group of (a) or (b),

R²²and R²³Independently of one another are C₁-C₈Alkyl radical, C₁-C₈Hydroxyalkyl or of formula- [ (CH)₂CH₂)-O]_n1-CH₂CH₂-OH, wherein n1 is 1 to 5,

R²⁴is H or C₁-C₈Alkyl, and

wherein

R²⁵May be the same or different at each occurrence and is a hydrogen atom, a halogen atom, C₁-C₁₈Alkyl radical, C₁-C₁₈Alkoxy or a group-C (═ O) -R²⁶，

R²⁶Is hydrogen atom, hydroxyl, C₁-C₁₈Alkyl, unsubstituted or substituted amino, unsubstituted or substituted phenyl or C₁-C₁₈Alkoxy, and

n3 is a number from 1 to 4,

m3 is a number from 2 to 4, an

The sum of m3 and n3 is 6.

8. A coating or printing ink composition comprising a composition according to any one of claims 1 to 7.

9. The coating or printing ink composition according to claim 8, comprising:

(i) the composition according to any one of claims 1 to 7,

(ii) a binder, and

(iii) optionally a solvent.

10. A security or decorative element comprising a substrate which may comprise a logo or other visible feature in or on its surface, and a coating on at least a portion of the substrate surface comprising a composition according to any one of claims 1 to 7.

11. The security or decorative element according to claim 10, wherein the coating comprising the composition according to any one of claims 1 to 7 shows a blue color in transmission and a metallic yellow color in reflection.

12. Security or decorative element according to claim 10 or 11, wherein the security element comprises a substrate, a coating comprising at least one liquid crystalline compound on at least a part of the substrate, wherein the coating is applied to the opposite side of the substrate if the substrate is transparent or translucent or to the surface side if the substrate is transparent, translucent, reflective or opaque, and a further coating located on at least a part of the coating comprising the liquid crystalline compound or directly on the substrate if the coating comprising the liquid crystalline compound is placed on the opposite side of the substrate, the further coating comprising a composition according to any one of claims 1 to 7; or

The security element consists of an interference-capable multilayer structure, wherein the interference-capable multilayer structure has a reflective layer, a dielectric layer and a partially transparent layer, wherein the dielectric layer is arranged between the reflective layer and the partially transparent layer, wherein the reflective layer is formed by a colored layer comprising a composition according to any one of claims 1 to 7; or a security element comprising a transparent carrier substrate, a layer comprising a Diffractive Optical Element (DOE) and a translucent functional layer comprising a composition according to any one of claims 1 to 7; or

The security or decorative element is a blister for tablets comprising a transparent carrier substrate comprising a translucent functional layer comprising a composition according to any one of claims 1 to 7; or

The security or decorative element is a package comprising a plastic film shaped part and a cover film, wherein the plastic film shaped part defines the front side of the package and the cover film defines the back side of the package and the cover film is based on a carrier substrate provided with a translucent functional layer comprising a composition according to any one of claims 1 to 7.

13. A product comprising a security or decorative element according to any one of claims 10 to 12.

14. Use of a security or decorative element according to any of claims 10 to 12 to prevent counterfeiting or copying of a document, security label or branded good having a value, right, identity.

15. A method of making a composition comprising silver nanoplates according to any of claims 1-7 comprising:

(a) preparing a solution (a) comprising a silver precursor, a compound of the formula and a polymer or copolymer obtained by a process comprising the steps of:

wherein

R¹Is H, C₁-C₁₈Alkyl, phenyl, C₁-C₈Alkylphenyl or CH₂COOH；

R²、R³、R⁴、R⁵、R⁶And R⁷Independently of one another is H, C₁-C₈Alkyl or phenyl;

y is O or NR⁸；

R⁸Is H or C₁-C₈An alkyl group;

k1 is an integer in the range of 1 to 500;

k2 and k3 are independently of each other 0 or an integer in the range of 1 to 250;

k4 is 0 or 1;

k5 is an integer in the range of 1 to 5;

i1) in a first step at least one of the compounds has a structural elementPolymerizing one or more ethylenically unsaturated monomers in the presence of the nitroxyl ether of (a),

wherein X represents a group having at least one carbon atom and which enables a radical X. generated by X to initiate polymerization; or

i2) In a first step in at least one stable nitroxide radicalAnd polymerizing one or more ethylenically unsaturated monomers in the presence of a free radical initiator; c wherein at least one monomer used in step i1) or i2) is acrylic acid or methacrylic acid₁-C₆Alkyl or C₁-C₆A hydroxyalkyl ester; and optionally

ii) a second step comprising modifying the polymer or copolymer prepared under i1) or i2) by transesterification, amidation, hydrolysis or anhydride modification, or a combination thereof;

water, and optionally a defoamer;

(b1) preparing a solution (b) comprising a reducing agent comprising at least one boron atom in a molecule, and water;

(b2) adding the solution (a) to the solution (b) and adding one or more complexing agents;

(c) adding an aqueous solution of hydrogen peroxide; and

(d) optionally adding a surface stabilizer to the mixture obtained in step (c), thereby synthesizing a composition comprising silver nanoplates.

Examples

The UV-visible spectrum of the dispersion was recorded on a Varian Cary 50 UV-visible spectrophotometer at a dispersion concentration such that an optical density of 0.3 to 1.5 was achieved with a 1cm light path.

TEM analysis of the dispersion and coating was performed on an EM 910 instrument from ZEISS in bright field mode at an electron beam acceleration voltage of 100 kV. At least 2 representative images at different magnifications were recorded to characterize the predominant particle morphology of each sample.

The diameter of the particles was determined from TEM images with the largest dimension of the nanoplatelets oriented parallel to the plane of the image based on the measurement of at least 300 randomly selected particles using the Fiji image analysis software.

The thickness of the particles was measured manually from TEM images based on measurements of at least 50 randomly selected particles with the largest dimension of the nanoplatelets oriented perpendicular to the plane of the images.

Example 1

a) In a 1L double-walled glass reactor equipped with an anchor stirrer, 365g of deionized water were cooled to +2 ℃. 13.62g of sodium borohydride were added and the mixture was cooled to-1 ℃ with stirring at 250 revolutions per minute (RPM, solution A).

In a 0.5L double-walled glass reactor equipped with an anchor stirrer, 132g of deionized water and 4.8g of MPEG-5000-thiol were combined, and the mixture was stirred at room temperature for 10 minutes. 72g of the product of example A3 of WO2006074969 were added and the resulting mixture was stirred at room temperature for a further 10 minutes for homogenization. A solution of 30.6g silver nitrate in 30g deionized water was added in one portion and the mixture was stirred for 10 minutes to give an orange-brown viscous solution. To this solution was added 96g of deionized water followed by 3g of Struktol SB2080 antifoam, pre-dispersed in 36g of deionized water. The resulting mixture was cooled to 0 deg.C (solution B) with stirring at 250 RPM.

Thereafter, solution B was added via a peristaltic pump to the subsurface solution a at a constant rate over 2 hours via a cooled (0 ℃) metering tube, resulting in a spherical silver nanoparticle dispersion. During pumping, solution a was stirred at 250 RPM.

After metering was complete, the reaction mixture was warmed to +5 ℃ over 15 minutes and a solution of 862mg KCl in 10g deionized water was added in one portion followed by 9.6g ethylenediaminetetraacetic acid (EDTA) in 4 portions at 10 minute intervals.

After the addition of the last portion of EDTA, the reaction mixture was stirred for 15 minutes at +5 ℃ and then warmed to 35 ℃ over 30 minutes and stirred at this temperature for 1 hour. At this point, hydrogen evolution is complete.

3.0ml of a 30% by weight aqueous ammonia solution was added, then 5.76g of solid NaOH was added, and the mixture was stirred at 35 ℃ for 15 minutes. 180ml of 50% by weight aqueous hydrogen peroxide solution were then added via a peristaltic pump to the subsurface reaction mixture at a constant rate over 4 hours with stirring at 250RPM, while maintaining the temperature at 35 ℃. This resulted in a dark blue color of the dispersion of silver nanoplates, which were cooled to room temperature. Adding 1.23g of a compound of the formula(B-3), and the mixture was stirred at room temperature for 1 hour.

b) Separation and purification of Ag nanoplates

B1) Decanting

9.6g of sodium lauryl sulfate was added to the reaction mixture and about 25g of anhydrous sodium sulfate powder was added in portions with stirring until the transmission color of the dispersion changed from blue to pink. The mixture was then left at room temperature for 24 hours without stirring, allowing the coagulated nanoplatelets to settle at the bottom of the reactor.

890g of supernatant was withdrawn from the reactor via a peristaltic pump and 890g of deionized water was added to the reactor. The mixture in the reactor was stirred at room temperature for 1 hour to redisperse the coagulated particles.

b2) Decanting

About 64g of anhydrous sodium sulfate powder was added in portions with stirring until the transmission color of the dispersion changed from blue to yellow pink. The mixture was then left at room temperature for 12 hours without stirring, allowing the coagulated nanoplatelets to settle at the bottom of the reactor. 990g of the supernatant was withdrawn from the reactor by a peristaltic pump, and 90g of deionized water was added to the reactor. The resulting mixture was stirred at room temperature for 30 minutes to redisperse the coagulated particles.

b3) Ultrafiltration in water

The resulting Ag nanosheet dispersion was ultrafiltered using a Millipore Amicon 8400 stirred ultrafiltration cell. The dispersion was diluted to 400g weight with deionized water and ultrafiltered to a final volume of about 50mL using a Polyethersulfone (PES) membrane with a cut-off of 300 kDa. This procedure was repeated a total of 4 times to provide a dispersion of 60g of Ag nanoplates in water. After completion of ultrafiltration, 0.17g of compound (B-3) was added to the dispersion.

The Ag content was 28.9 wt%; yield was about 89% based on total silver; the solids content (at 250 ℃) was 33.5% by weight; the purity of the silver was 86 wt% based on the solids content at 250 ℃.

b4) Ultrafiltration in isopropanol

The dispersion was further ultrafiltered in isopropanol. 60g of Ag nanosheet dispersion obtained after ultrafiltration in water was placed in a Millipore Amicon 8400 stirred ultrafiltration cell and diluted to a weight of 300g with isopropanol. The dispersion was ultrafiltered to a volume of about 50mL using a Polyethersulfone (PES) membrane with a cut-off of 500 kDa. This procedure was repeated a total of 4 times to provide a dispersion of 72g of silver nanoplates in isopropanol.

The Ag content was 24.1 wt%; the solids content (at 250 ℃) was 25.7% by weight; the purity of the silver was 93.5 wt% based on the solids content at 250 ℃.

UV-Vis-NIR spectroscopy at 9.8 x 10 in water^-5The Ag concentration of M is recorded. Lambda [ alpha ]_{Maximum value}700 nm; the maximum extinction coefficient ∈ 10200L/(cm × mol Ag), and FWHM 340 nm.

Refer to fig. 1. UV-Vis-NIR spectroscopy of Ag nanoplates of example 1b 4). The number average particle diameter is 93 plus or minus 40nm, and the number average particle thickness is 16 plus or minus 2.5 nm.

b5) Solvent switching

50g of the Ag nanoplate dispersion after ultrafiltration in isopropanol was placed in a250 mL round bottom flask and 15g of ethyl 3-ethoxypropionate was added. The resulting mixture was concentrated on a rotary evaporator at a pressure of 40 mbar and a bath temperature of 40 ℃ until no more solvent distilled off. The solids content was adjusted to 40% by weight by adding ethyl 3-ethoxypropionate.