Particles for electrophoretic displays

Abstract

This invention relates to particles comprising a pigment core particle encapsulated by a polymer, a process for their preparation, electrophoretic fluids comprising such particles, and electrophoretic display devices comprising such fluids.

Claims

1. Particles comprising an organic or inorganic pigment core particle encapsulated by a polymer having monomer units of a) at least one monomer, b) at least one polymerisable ionic liquid of Formula (I) or at least one polymerisable ionic liquid of Formula (II)
X.sub.1R.sub.1-A.sub.1.sup.?C.sub.1.sup.+Formula (I)
X.sub.2R.sub.2C.sub.2.sup.+A.sub.2.sup.?Formula (II) wherein X.sub.1 and X.sub.2 are a polymerisable group, R.sub.1 and R.sub.2 are a spacer group, A.sub.1.sup.? is an anion selected from borate, imide,phosphate, sulfonate, sulfate, succinate, naphthenate, or carboxylate, and C.sub.1.sup.+ a cation selected from phosponium, sulfonuim, oxonium, ammonium, uranium, thioronium, guanidinium or heterocyclic cations, wherein if C.sub.1.sup.+ is an ammonium cation [NR.sub.4].sup.+, R is a straight-chain or branched alkyl having 4-20 C atoms, and wherein A.sub.2.sup.? and C.sub.2.sup.+ are as follows: TABLE-US-00007 C.sub.2.sup.+ A.sub.2.sup.? c) optionally at least one polymerisable dye, and d) optionally at least one polymerisable steric stabiliser and the particles comprise at least one surfactant, wherein if C.sub.1.sup.+ is a heterocyclic cation it is of the following formula: ##STR00117## ##STR00118## ##STR00119## wherein R.sup.1to R.sup.4each, independently of one another, denote a straight-chain or branched alkyl having 1- 20 C atoms, which optionally can be partially fluorinated, but not in ?-position to hetero-atom, and which can also include oxygen or/and sulfur atoms in any positions in between carbon atoms; saturated, partially or fully unsaturated cycloalkyl having 5- 7 C atoms, which may be substituted by alkyl groups having 1-6 C atoms, where the substituents R.sup.1, R.sup.2, R.sup.3and /or R.sup.4 together may also form a ring system.

2. The particles according to claim 1, wherein X.sub.1 and X.sub.2 are a methacrylate, acrylate, methacrylamide, acrylonitrile, ?-substituted acrylate, styrene, vinyl or substituted vinyl group.

3. The particles according to claim 1, wherein R.sub.1 and R.sub.2 are an alkylene, polyether or poly-dimethylsiloxane group.

4. The particles according to claim 1, wherein the monomer is selected from the group consisting of methacrylate, acrylate and a mixture of methancrylate and acrylate.

5. The particles according to claim 1, wherein the at least on surfactant is soluble in non-polar organ solvents.

6. The particles according to claim 1, wherein a single organic or inorganic pigment core particle is coated with at least one surfactant and encapsulated by a polymer.

7. The particles according to claim 1, wherein the pigment core particle is titanium dioxide in the rutile, anatase, or amorphous modification or carbon black.

8. The particles according to claim 1, wherein the polymerisable steric stabiliser is a poly(dimethylsiloxane) macromonomer with at least one polymerisable group and a molecular weight in the range of 1000-50000.

9. A process for the preparation of the particles according to claim 1 comprising a) dispersing at least one organic or inorganic pigment particle in a solution comprising at least one non-polar organic solvent, optionally at least one surfactant, and optionally at least one polymerisable steric stabiliser; b) adding at least one monomer, at least one polymerisable ionic liquid of Formula (I) or at least one polymerisable ionic liquid of Formula (II), at least one initiator, and optionally at least one polymerisable dye; c) subjecting the dispersion of step b) to polymerisation; d) optionally washing by repeated centrifugation and redispersion in fresh solvent or filtration, and e) optionally isolating the resulting coated particles.

10. The process according to claim 9, wherein the process comprises the following steps: a) solubilising at least one surfactant and at least one polymerisable steric stabiliser in a non-polar organic solvent; b) dispersing at least one organic or inorganic pigment particle in the solution of step a) with optional sonication, milling or high shear mixing; c) adding at least one monomer, at least one polymerisable ionic liquid of Formula (I) or at least one polymerisable ionic liquid of Formula (II), at least one initiator, and optionally at least one polymerisable dye; d) subjecting the dispersion of step c) to heating and optionally sonication, milling or high shear mixing or stirring for polymerisation, e) optionally washing by repeated centrifugation and redispersion in fresh solvent or filtration, and f) optionally isolating the resulting coated particles.

11. An electrophoretic fluid comprising particles prepared by the process according to claim 9.

12. An optical, electrooptical, electronic, electrochemical, electrophotographic, electrowetting or electrophoretic displays and in security, cosmetic, decorative, and diagnostic applications, which comprises the particles according to claim 1.

13. A mono, bi or polychromal electrophoretic devices which comprises particles according to claim 1.

14. An electrophoretic fluid comprising particles according to claim 1.

15. An electrophoretic display device comprising the electrophoretic fluid according to claim 14.

16. The electrophoretic display device according to claim 15, wherein the electrophoretic fluid is applied by a technique selected from inkjet printing, slot die spraying, nozzle spraying, and flexographic printing, or deposition technique.

17. The electrophoretic display device according to claim 15, wherein the electrophoretic fluid is applied by a contact or contactless printing.

18. The particles according to claim 1, wherein the heterocyclic cations are selected from the group consisting of imidazolium, pyridinium, pyrrolidinium, trizalolium, morpholinium and piperidinium cation.

19. The particles according to claim 1, wherein the cation C.sub.1.sup.+ is tetrahexylammonium, tetradodecylammonium, tetrabutylphosphonium, tetracytophosphonium, trihexyltetradecylphosphonium, methyloctylimidazolium or dodecymethylpyrrolidinium.

20. The particles according to claim 1, wherein the anion A.sub.1.sup.? is 3-sulfopropylmethacrylate or 3-sulfopropylacrylate.

21. The particles according claim 1, wherein the at least one polymerisable ionic liquid of Formula (I) is present.

22. The particles according to claim 1, wherein said cation and anion are as follows: TABLE-US-00008 Cation anion

23. The particles to claim 1, wherein the cation C.sub.1.sup.+ is selected from the group consisting a tetraalkylammonium, tetraalkylphosphonium, N-alkylpyridinium, N,N-dialkypyrrolidinium, 1,3-dialkylimidazolium, and trialkulsufonium cation, wherein if C.sub.1.sup.1 is an ammonium cation [NR.sub.4].sup.+ R is a straight-chain or branched alkyl having 4-20 C atoms.

Description

EXAMPLES

(1) PDMS monomers, are purchased from Fluorochem, UK. In the following experiments a terminated monomethacrylate of molecular weight of 10,000 is used. Reagents and dodecane are purchased from Sigma-Aldrich Company and used without further purification. AIBN initiator is purchased from VWR. V59 initiator is purchased from Wako. Non-aqueous dispersion stabiliser (NADS) is purchased from ICI. Polymerisable ionic liquids are prepared before use as described above. PILs with cationic monomers can be prepared by methods described in WO 2012/072218. Titanium dioxide TR92 is obtained from Huntsman, RDI-S is obtained from Sachtleben, Carbon black used is FW200 from Evonik.

(2) Yellow dye (Dye 1) synthesis is previously disclosed in WO 2012/019704/example 24.

(3) Black dye (Dye 3) synthesis is previously disclosed in WO 2013/079146019704/example 3.

(4) Particle size is measured by SEM and image analysis. One drop of a particle dispersion is added to 2.5 ml heptane. One drop of this solution is deposited onto a silica wafer attached to the SEM stub. Samples are sputtered by gold for 120 seconds at 18 mA before being assessed in the SEM chamber.

(5) The electrophoretic fluids are prepared by vortex mixing 3 wt % of particles, 3 wt % of AOT (sodium bis(2-ethylhexyl) sulfosuccinate; 5 wt % in dodecane), and 94 wt % of dodecane. The dispersion is then roller mixed for 30 minutes. This formulation is used for the zeta potential measurement. For the reflective Y values measurements the following formulation is used: 15 wt % of particles, 3 wt % of AOT (sodium bis(2-ethylhexyl) sulfosuccinate; 5 wt % in dodecane), and 82 wt %. For black absorbance measurements the following formulation is used: 1 wt % of particles, 1 wt % of AOT (sodium bis(2-ethylhexyl) sulfosuccinate; 5 wt % in dodecane), and 98 wt %.

(6) The Zeta potentials of the formulations are performed using a Malvern NanoZS particle analyser unless otherwise stated. This instrument measures the size of particles in dispersion and the zeta potential of an electrophoretic fluid. The Zeta potential (ZP) is derived from the real-time measurement of the electrophoretic mobility and thus is an indicator of the suitability of the fluid for use in electrophoretic applications.

(7) Samples for analysis are prepared from PIL containing particle dispersions with known particle weight content. When using additives, surfactants are added at a concentration so that the ratio of particles to surfactant is 1:1 by weight.

(8) Preparation of PILs

(9) (A) MOTMA Based PILs:

(10) Preparation of MOTMA PF6.

(11) MOTMA Cl (5.0 g, 75% in water) is weighed into a round bottom flask and acetonitrile (10 ml) is added. Separately potassium hexafluorophosphate (3.66 g) added to the acetonitrile solution. The mixture is stirred vigorously overnight at room temperature. The potassium by-product is then removed by filtration, and washed with further acetonitrile. The solvent is concentrated in vacuo. The residue is redissolved in DCM, refiltered and concentrated to yield the ionic liquid product.

(12) (B) Vim Based Ionic Liquids:

(13) Preparation of C12Vim Br

(14) Vinyl imidazole (10.0 g) and bromododecane (29.13 g) are weighed into a round bottomed flask and acetonitrile is added (30 ml) and stirred at 65? C. until consumption of vinyl imidazole is evident by NMR analysis. The reaction mixture is cooled and the mixture concentrated in vacuo. The resulting material is recrystallised using ethyl acetate.

(15) Preparation of C12Vim BuSO3

(16) Amberlite IRA-400 (Cl) resin (100 ml) is loaded into a column and flushed with water until the solvent runs clear. C12Vim Br (10.0 g) is dissolved in acetonitrile (100 ml) and is passed slowly through the resin. The resin is washed with further acetonitrile. The solvent is concentrated in vacuo. The resulting chloride salt is then re-dissolved in acetonitrile (20 ml). In a separate flask the sodium butanesulfonate (5.13 g) is dissolved in acetonitrile. This solution is added drop wise to the stirring chloride salt and is stirred overnight. The resulting suspension is filtered and concentrated in vacuo. The residue is re-dissolved in DCM, re-filtered and concentrated to yield the product ionic liquid.

(17) Preparation of C12Vim NTf

(18) C12Vim Br is charged to a flask (3.0 g). In a separate beaker, lithium bis(trifluoromethane)sulfonimide (2.63 g) is dissolved in water. The aqueous solution is added to the bromide salt and the mixture is stirred overnight. DCM (20 ml) is added and the phases are then separated. The aqueous phase is extracted with further DCM. The combined organics are washed several times with water to remove traces of LiBr and then concentrated in vacuo to yield the ionic liquid.

(19) Preparation of Bromide Salts

(20) (Used for the Preparation of all Imidazolium and Pyrridinium Based Ionic Liquids)

(21) ##STR00106##

(22) Methyl imidazole (1 eq) and a bromoalkane (1.1 eq) are weighed into a round bottomed flask and acetonitrile is added. The flask is equipped with a magnetic stirrer bar, and a condenser. The mixture is stirred at 65? C. until consumption of methyl imidazole is evident by NMR analysis. The reaction mixture is then cooled and the mixture concentrated in vacuo. The resulting material is recrystallised using ethyl acetate.

(23) Anion Exchange

(24) (Used for the Preparation of all SPMA Ionic Liquids)

(25) ##STR00107##

(26) Amberlite IRA-400 (Cl) resin (100 ml) is loaded into a column and flushed with water until the solvent runs clear. A bromide salt (10 g) is dissolved in acetonitrile (100 ml) and is passed slowly through the resin. The resin is washed with further acetonitrile. The solvent is then concentrated in vacuo. The resulting chloride salt is then re-dissolved in acetonitrile (20 ml). In a separate flask the 3-sulfopropylmethyacylate potassium salt (1.1 eq) is dissolved in acetonitrile. This solution is added drop wise to the stirring chloride salt, once addition is complete allowed to stir at room temperature overnight. The resulting suspension is then filtered and concentrated in vacuo. The residue is re-dissolved in DCM, re-filtered and concentrated to yield the product ionic liquid.

(27) Preparation of Dye 2

(28) ##STR00108##

Step 1: 4,4-(5-acetamido-2-methoxyphenylazanediyl)bis(butane-4,1-diyl)diacetate

(29) A stirred mixture of 3-amino-4-methoxyacetanilide (18.0 g, 0.1 mol), 4-bromobutyl acetate (48.8 g, 0.25 mol), 1-methyl-2-pyrrolidinone (50 ml) and sodium bicarbonate (55.2 g, 0.66 mol) is heated in an oil bath at 105? C. overnight, allowed to cool and then poured into water (500 ml). After stirring for 30 minutes, the oil that separates is extracted with dichloromethane (150 ml), the organic layer is dried (MgSO.sub.4) and evaporated to give a thick brown oil (57.0 g). The oil is used directly without further purification (95% purity).

Step 2: 4,4-(5-amino-2-methoxyphenylazanediyl)dibutan-1-ol

(30) Crude 4,4-(5-acetamido-2-methoxyphenylazanediyl)bis(butane-4,1-diyl)diacetate (0.1 mol) is dissolved in dioxane (200 ml) and 1 M LiOH (300 ml) is added. After 15 minutes, the reaction is neutralised with 35% HCl (5 ml) then evaporated to give a brown oil. The oil is dissolved in a mixture of water (200 ml) and 35% HCl (100 ml) and heated for 4 h at 90? C., allowed to cool to RT, basified to pH 11.0 and the resultant oil is extracted with DCM (2?150 ml), dried (MgSO.sub.4) and evaporated to give a dark brown viscous oil. (28.3 g, 100%). The crude product is used directly without purification.

Step 3: N-(3-(Bis(4-hydroxybutyl)amino)-4-methoxyphenyl)-3,5,5-trimethylhexanamide

(31) 4,4-(5-Amino-2-methoxyphenylazanediyl)dibutan-1-ol (50 mmol) is dissolved in dichloromethane (200 ml) and to this is added triethylamine (7.6 g, 75 mmol). 3,5,5-Trimethylhexanoyl chloride (8 ml) is added dropwise. Methanol (100 ml) is added and the reaction is stirred overnight and is used directly without further purification.

Step 4: (E)-N-(5-(Bis(4-hydroxybutyl)amino)-2-((2-bromo-6-cyano-4-nitrophenyl)diazenyl)-4-methoxyphenyl)-3,5,5-trimethylhexanamide

(32) Sulfuric acid (80% w/w, 75 ml) is cooled to 5? C. and 6-bromo-2-cyano-4-nitroaniline (9.7 g, 40 mmol) is added and stirred for 10 minutes at <5? C. until fully dispersed. Nitrosyl sulfuric acid 40% (w/w) in sulfuric acid (15.3 g, 0.048 mol) is added in portions at 3-5? C. over 30 minutes, then stirred for a further hour at <5? C. N-(3-(Bis(4-hydroxybutyl)amino)-4-methoxyphenyl)-3,5,5-trimethylhexanamide (assume 41 mmol) is diluted with methanol (100 ml), cooled externally in an ice bath to 5? C. and solid ice (50 g) and water (50 ml) are added. Sulfamic acid (10 ml) is added. The above diazonium salt solution is added dropwise over 1 hour. The reaction is stirred overnight, then the solid filtered-off and dried overnight at 40? C. (13.4 g, 50%). The crude product is recrystallised from hot IMS to give the required dye as a green crystalline solid (8.9 g, 32%).

Step 5: (E)-N-(5-(bis(4-hydroxybutyl)amino)-2-((2,6-dicyano-4-nitrophenyl)diazenyl)-4-methoxyphenyl)-3,5,5-trimethylhexanamide

(33) N-(5-(Bis(4-hydroxybutyl)amino)-2-((2-bromo-6-cyano-4-nitrophenyl)diazenyl)-4-methoxyphenyl)-3,5,5-trimethylhexanamide (8.8 g, 13.0 mmol) is suspended in 1-methyl-2-pyrrolidinone (15 ml) and warmed to 55? C. to dissolve. Zinc cyanide (0.82 g, 7 mmol) followed by copper(I) cyanide (0.4 mg, 0.45 mmol) are added and the reaction heated to 105? C. (bath temp). After 3 h, external heating is removed and methanol (45 ml) is added. The resultant crystalline solid is filtered off. The solid is recrystallised from IMS (6.1 g, 75%).

Step 6: (E)-4,4-(4-((2,6-dicyano-4-nitrophenyl)diazenyl)-2-methoxy-5-(3,5,5-trimethyihexanamido)phenylazanediyl)bis(butane-4,1-diyl)bis(3-chloropropanoate)

(34) (E)-N-(5-(Bis(4-hydroxybutyl)amino)-2-((2,6-dicyano-4-nitrophenyl)diazenyl)-4-methoxyphenyl)-3,5,5-trimethylhexanamide (6.0 g, 9.7 mmol) and sodium bicarbonate (8.1 g, 97 mol) are suspended in dichloromethane (120 ml) and 3-chloropropionyl chloride (3.7 g, 29.1 mmol) added. The mixture is heated at 40? C. overnight. Methanol (300 ml) is added and the mixture is concentrated in vacuo to half volume. The precipitated tarry solid is filtered off. The solid is added to dichloromethane (100 ml) and stirred for 5 minutes to dissolve, before inorganics are removed by filtration. The dichloromethane solution is evaporated to give the crude product as a black tarry solid (7.7 g, 90%). The material is purified over silica gel, eluting with 2-5% ethyl acetate in dichloromethane. Combination and evaporation of the pure fractions afford the required compound as a black tarry solid (6.8 g, 80%), which is >99% pure by HPLC.

Step 7: (E)-4,4-(4-((2,6-dicyano-4-nitrophenyl)diazenyl)-2-methoxy-5-(3,5,5-trimethylhexanamido)phenylazanediyl)bis(butane-4,1-diyl)bis(acrylate)

(35) (E)-4,4-(4-((2,6-dicyano-4-nitrophenyl)diazenyl)-2-methoxy-5-(3,5,5-trimethylhexanamido)phenyl-azanediyl)bis(butane-4,1-diyl)bis(3-chloropropanoate) (6.8 g, 8.5 mmol) is dissolved in dichloromethane (68 ml) and triethylamine (6.0 ml, 43 mmol) is added. The reaction is warmed for 3 h at 35? C. The solution is washed with 0.2 N HCl, then with water, dried (Na.sub.2SO.sub.4) and filtered. The solution is evaporated and the resultant tarry solid redissolved in dichloromethane (200 ml), diluted with methanol (400 ml) and stirred overnight allowing solvent to slowly evaporate. The resultant solid is filtered-off, washed with methanol on the filter and dried under high vacuum until a constant weight is obtained. The required dye was obtained as a dark blue solid (5.4 g, 87%). Mp: 120-121? C., ?.sub.max (EtOAc) 642 nm (98,000), ? band width=70 nm. .sup.1H NMR (CDCl.sub.3, 300 MHz) ? 0.92 (9H, s), 1.03 (3H, d, J 6.6), 1.17 (1H, dd, J 14.0, J 6.6), 1.34 (1H, dd, J 14.0, J 3.7), 1.81 (8H, m), 2.16 (1H, m), 2.42 (1H, dd, J 14.0, J 8.0) 2.52 (1H, dd, J 14.0, J 6.5), 3.71 (4H, m), 3.88 (3H, s), 4.23 (4H, t, J 6.0), 5.84 (2H, dd, J 10.5, J 1.5), 6.13 (2H, dd, J 17.3, J 10.5), 6.42 (2H, J 17.3, J 1.5), 7.54 (1H, s), 8.32 (1H, s), 8.63 (2H, s), 9.27 (1H, br. s).

Example 1

Synthesis of White Reflective Particles with Positive Zeta Potential with AOT Surfactant in Dodecane

(36) PDMS-MA (2.08 g), dodecane (75 g), Span 85 (1.03 g of 50% solution in dodecane) and titania (10.3 g) are charged to 250 mL three-necked flask. Subaseals are placed into each of the necks, and the flask is placed in a sonic bath at 100% power, 37 Hz for 30 minutes. The flask is removed from the sonic bath and is fitted with an overhead stirrer, condenser and nitrogen bubbler. Nitrogen is bubbled through the dispersion for 30 minutes. The flask is replaced into a sonic bath preheated to 80? C. and at 100% power, 37 Hz. A mixture prepared from AIBN (0.214 g), MMA (10.3 g) and N6666 SPMA (0.103 g) is added to the dispersion at a rate of 3.8 mL per hour. The reaction is continued for 4 hours (from the start of addition). The flask is removed from the sonic bath and allowed to cool to room temperature.

(37) The dispersion is filtered through a 50 micron cloth and washed 3 times in dodecane using centrifugation for 15 minutes at 10 000 rpm, removing the supernatant from the particles and replacing with fresh dodecane. Solid content is calculated to be 51.1 weight %. Average particle size observed by SEM and measured using Image J software is 514 nm. Particles are observed by TEM and show clearly individual pigment particles coated with a layer of polymer.

(38) An electrophoretic ink is prepared by vortex mixing 0.0615 g of particles (51.1% solid content), 0.0617 g of AOT (5.00 wt % solution in dodecane) and 1.9264 g of dodecane. The dispersion is then roller mixed for 30 minutes. Two drops of this dispersion is added to 1.0 ml of dodecane and roller mixed for 30 minutes. The zetapotential of the diluted sample is measured using a Malvern NanoZS particle analyser. zP: +44 mV

(39) An electrophoretic ink is prepared by vortex mixing 0.3015 g of particles (51.1% solid content), 0.0603 g of AOT (5.00 wt % solution in dodecane) and 1.6491 g of dodecane. The dispersion is roller mixed for 30 minutes.

(40) The colour coordinates of this dispersion are measured using an X-rite Color i5 spectrophotometer in a 50 micron thickness glass cell and are: L* 76.38, a* ?2.12, b* ?2.03 and Y is 50.50.

(41) Similarly prepared are the following particles:

(42) TABLE-US-00004 TABLE 4 Example TiO2 PIL % PIL zp/mV Y Size 1 TR92 N6666 SPMA 1.0 +44 50.5 514 2 TR92 P8888 SPMA 1.0 +145 52.1 503 3 TR92 NO PIL 0 ?10.9 51.3 530 Comparative example 4 RDI-S N6666 SPMA 0.25 +109 50.33 621 5 RDI-S N6666 SPMA 0.5 +107 50.42 467 6 RDI-S N6666 SPMA 0.75 +119 51.55 502 7 RDI-S N6666 SPMA 1.0 +135 52.48 580 8 RDI-S N6666 SPMA 5.0 +207 50.9 528

Example 9

Synthesis of Coloured Reflective Particles with Positive Zeta Potential with AOT Surfactant in Dodecane

(43) PDMS-MA (2.08 g), dodecane (75 g), Span 85 (1.03 g of 50% solution in dodecane) and titania TR92 (10.3 g) are charged to 250 mL three-necked flask. Subaseals are placed into each of the necks, and the flask is placed in a sonic bath at 100% power, 37 Hz for 30 minutes. The flask is removed from the sonic bath and is fitted with an overhead stirrer, condenser and nitrogen bubbler. Nitrogen is bubbled through the dispersion for 30 minutes. The flask is replaced into a sonic bath preheated to 80? C. and at 100% power, 37 Hz. A mixture prepared from AIBN (0.21 g), MMA (10.3 g) and N6666 SPMA (0.10 g), Yellow dye 1 (1.03 g) and toluene (6 ml) (is added to the dispersion at a rate of 3.8 mL per hour. The reaction is continued for 4 hours (from the start of addition). The flask is removed from the sonic bath and allowed to cool to room temperature.

(44) The bright yellow dispersion is filtered through a 50 micron cloth and washed 3 times in dodecane using centrifugation for 15 minutes at 10 000 rpm, removing the supernatant from the particles and replacing with fresh dodecane. Solid content is calculated to be 53.0 weight %. Average particle size observed by SEM and measured using Image J software is 553 nm.

(45) An electrophoretic ink is prepared using the same procedure as in example 1. The zetapotential of the diluted sample is measured: zP: +105 mV The colour coordinates of this yellow dispersion are: L* 74.38, a* ?9.98, b* 61.82 and Y is 47.30.

(46) Similarly prepared are the following particles:

(47) TABLE-US-00005 TABLE 5 Wt % Wt % Ex. Dye dye PIL PIL zp/mV Y L* a* b* 9 1 10 N6666 1.0 +105 47.30 74.38 ?9.98 61.82 SPMA 10 2 3 N6666 1.0 +165 22.92 54.99 ?12.31 ?21.54 SPMA 11 1 5 NO PIL 0 ?66 52.29 77.46 ?14.92 49.08 Comp. ex.

Example 12

Preparation of Carbon Black Polymer Hybrid Particles with Polymerisable Ionic Liquid

(48) PDMS-MA (2.08 g), dodecane (75 g), Span 85 (0.2 ml of 50% solution in dodecane) and carbon black (1.00 g) are charged to 250 mL three-necked flask. Subaseals are placed into each of the necks, and the flask is placed in a sonic bath at 100% power, 37 Hz for 30 minutes. The flask is removed from the sonic bath and is fitted with an overhead stirrer, condenser and nitrogen bubbler. Nitrogen is bubbled through the dispersion for 30 minutes. The flask is replaced into a sonic bath preheated to 80? C. and at 100% power, 37 Hz. A mixture prepared from AIBN (0.214 g), MMA (5.15 g) and N6666 SPMA (0.05 g) is added to the dispersion at a rate of 3.8 mL per hour. The reaction is continued for 4 hours (from the start of addition). The flask is removed from the sonic bath and allowed to cool to room temperature.

(49) The dispersion is filtered through a 50 micron cloth and washed 3 times in dodecane using centrifugation for 15 minutes at 10 000 rpm, removing the supernatant from the particles and replacing with fresh dodecane. Solid content is calculated to be 51.1 weight %. Average particle size observed by SEM and measured using Image J software is 514 nm.

(50) An electrophoretic ink is prepared in the same way as example 1.

(51) The colour coordinates of this dispersion are: L* 53.72 and Y is 21.72.

Example 13

Preparation of Black Polymer Particles (No Pigment)

(52) Methyl methacrylate (61.74 g), NAD stabiliser (10.50 g), methacrylic acid (1.25 ml), Yellow Dye 1 (0.93 g) and Black Dye 3 (5.25 g), 1-octanethiol (0.38 ml) and dodecane (75.6 g) are charged to a 250 ml 3-necked flask equipped with an overhead stirrer set at 300 rpm, under a nitrogen atmosphere. The reaction is heated to 77? C., at which temperature V-59 is added. The reaction is stirred for 2 hours at this temperature, and is then allowed to cool to room temperature. The reaction is filtered through a 50 micron cloth. The dispersion is cleaned by centrifugation (3?10000 rpm) and replacing the supernatant with clean dodecane. Solid content is calculated to be 50.9 weight %. Average particle size observed by SEM and measured using Image J software is 862 nm with a polydispersity below 5%.

Example 14

Dual Particle Black and White EP Fluid

(53) An electrophoretic ink is prepared by vortex mixing 0.0539 g of Black dyed PMMA particles Example 13 (50.9% solids content), 0.1614 g of White particles from example 1 (51.1% solids content), 0.0165 g of span 85, and 0.0138 g of AOT (40.00 wt % solution in dodecane) and 0.3048 g of dodecane. The dispersion is roller mixed for 30 minutes.

(54) The resulting dispersion is characterised using an Autronics DMS-301 with hemisphere attachment, to give the following data:

(55) TABLE-US-00006 TABLE 6 Black Ton Toff White State State Contrast (20 V) (20 V) Reflectivity reflectivity Ratio (response (response Formulation (+20 V) (?20 V) (20 V) time rise) time fall) Example 14 20.47% 2.37% 8.64:1 952 ms 537 ms