Halogen-Free, UV-Curable High Refractive I ndex Materials for Light Managem ent Dr. Mike J. Idacavage Strategy Technology Group Cytec Industries, Inc. October 12, 2010 Georgia Tech Nano@Tech 1 sem inar series
Functions of Refractive I ndex 3 Functions of Refractive I ndex • Refraction: Light rays change direction when they cross the interface from one material (n 1 ) to another material (n 2 ); • Reflection: Light reflects partially from the inter-surfaces of 2 materials that have different refractive index; Dispersion: Dispersive effect due to the • diversity of the wavelengths of the light, the bending effect being frequency dependent. • Snell’s Law -Refraction Georgia Tech Nano@Tech 2 sem inar series
Potential Applications of High RI Materials • Brightness enhancing films • Anti-reflective coatings • High-reflective coatings • Bragg reflectors • Optical fiber coatings • Plastic lenses • Graded index optical lenses • Fresnel lenses • Photonic devices • Security Coatings Various applications for high refractive index materials Georgia Tech Nano@Tech 3 sem inar series
Brightness Enhance Film s Cited from A m icro-replicated prism film ( m ade from high RI m aterials) that is used to increase display brightness by m anaging the exit angle of light . Georgia Tech Nano@Tech 4 sem inar series
Material Requirem ents • Optical Properties • Mechanical Properties • Adhesion • Formulation Capability • Process-ability • Cost • Product Stewardship Requirements driving need for new materials/ technologies Georgia Tech Nano@Tech 5 sem inar series
Theory for Making High RI Materials Lorentz - Lorenz Equation Higher refractive index ( n) is often achieved by + π γ ρ 8 N M increasing polarizability = 2 A 3 n ( γ ) and/ or increasing − π γ ρ M 4 N density ( ρ ) . 3 A 1. Aromatic Rings ≡ n Refractive Index 2. Halogen Atoms (Cl, Br) ≡ M Repeat Unit MW 3. Hetero Atoms (S, P) ≡ N Avogadro' s Constant A 4. Inorganic-Organic γ ≡ Polarizabi lity Hybrid Nanomaterials ρ ≡ Density Polarizability num ber A/M H C N O F S P Cl Br I Ti Zr CH 4 C 6 H 6 γ 0.67 1.76 1.10 0.80 0.56 2.90 3.63 2.18 3.05 5.35 14.6 17.9 2.59 10.0 Theory guides our new m aterials R&D C 6 H 6 Georgia Tech Nano@Tech 6 sem inar series
Technical Strategy Traditional Approach - Organic Synthesis/ Formulation New Approach - Inorganic - Organic Hybrid Nanocomposite – Nanoparticle Dispersion Overall technical strategy for the development of High RI Materials. Georgia Tech Nano@Tech 7 sem inar series
Organic Synthesis/ Form ulation Highly Arom atic ( Meth) Acrylate Resins 2 -Phenoxyethyl acrylate O – n = 1.51, liquid’ O – Viscosity 20 cPs @ 25°C O – Aromatic rings = 1 Bisphenol-A-epoxy diacrylate – n = 1.55, – Viscosity 800,000 cPs @ 25°C – Aromatic rings = 2 O OH O O O O OH O Compromise between refractive index and viscosity Georgia Tech Nano@Tech 8 sem inar series
Organic Synthesis/ Form ulation Halogenated Acrylates Chlorinated Isobornyl Acrylate n = 1.54, liquid Very high concentration of chlorine O Br O O Tribromophenoxyethyl Acrylate n = 1.56, solid Br Br High concentration of bromine Br Br O Pentabromophenyl methacrylate Br O C C CH 2 n = 1.71, solid CH 3 Br Br Very high concentration of bromine Higher halogenation, higher RI value, but … Georgia Tech Nano@Tech 9 sem inar series
New dem ands from global m arkets • Halogen-Free materials are the preferred requirement globally due to growing environmental concerns; • Higher Refractive Index value – for higher performance; • Lower viscosity requirement for coat-ability @ room temperature. Fast market changes generate many technology challenges Georgia Tech Nano@Tech 10 sem inar series
Heteroatom Resins from Organic Synthesis/ Form ulation Phenylthiolethyl acrylate – n = 1.56, liquid O – Good diluent, S CH 2 CH 2 O C C CH 2 MPSMA Bis( m ethacryloylthiophenyl) sulfide – n = 1.66, solid O CH 3 S C C CH 2 H 2 C C C S S CH 3 O Existing technologies for m aking halogen-free, high RI m aterials Georgia Tech Nano@Tech 11 sem inar series
Heteroatom Resins from Organic Synthesis/ Form ulation Synthesized Heteroatom Urethane ( Meth) acrylates Oligomer 1 Oligomer 2 Properties Halogen Free Yes Yes Appearance Clear liquid Clear, dark brown, viscous liquid Color (Gardner) <1 <12.5 20 RI (L,), n D 1.606 1.639 Molecular Weight (Mn) 560 1,600 GPC Viscosity (cPs @ 60 ° C) 1,250 15,000 Density (g/cm 3 ) 1.18 1.20 Multi-arom atic rings and hetero atom -containing Urethane ( Meth) acrylate – New I nvented proprietary technology Georgia Tech Nano@Tech 12 sem inar series
Heteroatom Resins from Organic Synthesis/ Form ulation Perform ance Data of 3 Form ulations based on heteroatom containing arom atic urethane ( m eth) acrylate oligom ers Performance Formulation 1 Formulation 2 Formulation 3 Halogen Free Yes Yes Yes 20 (liquid) n D 1.5653 1.5658 1.5706 RI of Cured film 1.5886 1.5883 1.5906 Viscosity at 25 ° C 1840 1290 5500 Viscosity at 60 ° C 149 113 325 Pencil hardness 2H 1H H UV-cure Dosage (mJ/cm 2 ) 880 880 880 Tensile, psi 2700 2039 2337 Elongation, % 59 20 37 Modulus, psi 49508 52798 77719 Toughness, psi 764 279 652 Adhesion to PET film, 5B=100% adhesion 5B 5B 5B Higher RI provides higher latitude for form ulating Georgia Tech Nano@Tech 13 sem inar series
Halogen-free, Sulfur-free Resins from Organic Synthesis/ Form ulation A new halogen-free and S-free oligom er has been developed. Oligom er Properties Halogen Free, Sulfur-free Yes Molecular Weight (Mn) by GPC 2 ,7 5 0 Appearance Clear, viscous liquid Color ( Gardner) < 1 RI ( L, 5 8 9 nm @ 2 0 ° C) 1 .5 9 9 Viscosity ( cP @ 6 0 ° C) 1 1 7 ,0 0 0 Density ( g/ cm 3 ) 1 .1 6 Functionality 2 ( can be higher) The viscosity reduction can be achieved w ith reactive m onom er dilution. Georgia Tech Nano@Tech 14 sem inar series
RI of I norganic Com pounds Refraction Index, n D Compound Crystalline Form Al 2 O 3 Col. Hex. 1.768, 1.76 RI values of Sb 2 O 4 N. Cervantite(W powder), 2.00, N. Senarmontite(Sb 2 O 3 ,W cub), or (Sb 2 O 3 Sb 2 O 5 ) 2.087, som e N. Valentinte (Sb 2 O 3 , Col rhomb) 2.18, 2.35, inorganic CdO Brown Cub 2.490 CaO 2 White tetr. 1.895 com pounds Cu 2 O N. Cuprite, red, oct. cub. 2.705 FeO N. Wuestite, blk. Cub. 2.32 Fe 2 O 3 N. Hematite, red-brn to blk trig 2.94-3.01 PbO Massicot. Yel. Rhomb. 2.51-2.71 MnOMnO 3 (II,III) N. Hausmanntite, blk. Tetr(rhomb) 2.15-2.46 SnO 2 N. Cassiterite, white tetr.or hex. or rhomb) 1.997-2.093 TiO 2 N. octahedrite, anatase, br-blk, tetr 2.554-2.493 N. Brookite, white, rhomb 2.586-2.741 N. Rutile, Col. tetr 2.616-2.903 N. Zincite, white hex. ZnO 2.008-2.029 N. Sphalerite, col. Cub. ZnS 2.368 Yelsh. to redsh. Cub. ZnSe 2.89 Red cub. ZnTe 3.56 N. Baddeleyite, col.-yel-brn monocl. ZrO 2 2.13-2.19-2.20 Targeted inorganic/ organic hybrid nanocom posites due to the high refractive index of inorganic com pounds Georgia Tech Nano@Tech 15 sem inar series
I norganic-Organic Hybrid Nanocom posite Tw o Possible Technologies for Preparing I norganic-Organic Hybrid Nanocom posite Materials A. Sol-Gel Chem istry and Process: The process involves the transition of a system from a liquid "sol“ ( m ostly colloidal) phase into a solid "gel" phase. B. Nanoparticle Dispersion – Nanocom posite: Use com m ercially available nanoparticles as raw m aterials --- Surface m odify nanoparticles --- Disperse surface m odified nanoparticles into UV resins. Hybrid nanocomposite combines advantages of inorganic and organic phases . Georgia Tech Nano@Tech 16 sem inar series
Sol-Gel Process • Metal alkoxides, chlorides or nitrates are hydrolyzed and condensed • Low temperature reaction conditions required • Condensation generates highly crosslinked M-O- M networks with H 2 O or ROH as byproducts Georgia Tech Nano@Tech sem inar series 17
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