Nanocomposite materials with dynamically adjusting refractive index and methods of making the same

Abstract

A concept and synthesis technology for a composite nanoparticle material which can be used to develop nanocomposite films and suspension with 1) dynamic refractive index control across a wide temperature and wavelength of light, and specified refractive index range, or 2) magnetic susceptibility or electronic conductivity over a wide temperature, magnetic field and electric field range. Core-shell nanoparticles can be made from two or more materials whose temperature dependent, electric field dependent or magnetic field dependent properties compensate one another will dynamically maintain a targeted refractive index, electronic conductivity or magnetic susceptibility over a specified temperature, electric and/or magnetic field range. Mixtures of composite nanoparticles with complementary behavior can optionally be used to widen the operational range of the nanocomposite material further or dampen temperature dependency in a controlled manner, e.g. using a non-random distribution of particles to affect a compensating gradient in the property of interest.

1 . A solid layered composite nanoparticle having properties with reduced temperature dependency, comprising: a core and an outer shell, wherein the outer shell includes multiple layers, and wherein said core and said outer shell have compositions which are different and chosen such that the composite nanoparticle exhibits a buffered temperature dependency with respect to at least one physical property, said physical property selected from the group consisting of refractive index, magnetism, electrical conductivity, and combinations thereof. 
     
     
         2 . The nanoparticle in  claim 1 , wherein each of the core and outer shell, including any layers within the outer shell, are covalently bonded to adjacent layers. 
     
     
         3 . The nanoparticle in  claim 2 , where the covalent bonding between layers is of the form selected from the group consisting of direct, via homo, via hetero, and combinations thereof, wherein the homo and the hetero independently include bi and trifunctional crosslinkers which include functional groups NH 2 , SH 2 , SCN, OH, COOH, TiO 3 , SiO 3 , PO 4 , or combinations thereof. 
     
     
         4 . The nanoparticle in  claim 1 , wherein at least some of the multiple layers of the outer shell consist of an organic polymer covalently bonded to adjacent underlying and overlying oxide or metal layers. 
     
     
         5 . The nanoparticle in  claim 4 , wherein the organic polymer layer is selected from the group consisting of optically active polymers, conductive polymers, viscoelastic polymers, elastomers, and combinations thereof. 
     
     
         6 . The nanoparticle in  claim 1 , wherein at least one of the core and the multiple layers of the outer shell is doped with a dye. 
     
     
         7 . The nanoparticle in  claim 6 , wherein the organic dye is a lanthanide-based dye. 
     
     
         8 . The nanoparticle in  claim 1 , wherein at least one of the multiple layers of the outer shell is doped with transition metal ligand complexes made from elements from rows 4 and 5 of the periodic table. 
     
     
         9 . The nanoparticle in  claim 1 , wherein one or more of the multiple layers of the outer shell is modified by at least one post processing methods selected from the group consisting of heat, gamma irradiation, chemical reaction, and combinations thereof. 
     
     
         10 . The nanoparticle in  claim 1 , wherein some of the multiple layers of the outer shell include repeating layers that are mesoporous, having been synthesized in the presence of a surfactant which self-assembles into nanosized structures on the surface of the core nanoparticle or its succeeding layers and wherein the repeating mesoporous layers are configured for deposition of metal oxide or pure metal. 
     
     
         11 . The nanoparticle in  claim 1 , wherein the core and outer shell are selected such that the composite nanoparticle exhibits substantially no refractive index or reflectivity change as a function of external temperature 
     
     
         12 . A concentrated nanoparticle suspension comprising the nanoparticle of  claim 1  in silicone oil, mineral oil, or other inorganic or organic solvent. 
     
     
         13 . The nanoparticle in  claim 1 , wherein the core material and repeating layers are selected from the group consisting of IIA, IIB, IVB, VB, VIB, VIIB, VIIIB, IB, IIB, IIIA, IVA and VA elements, their oxides, and combinations thereof, such that the composite nanoparticles exhibit temperature or electric field independent or tunable diamagnetism or ferromagnetism. 
     
     
         14 . A nanocomposite thin film coating, comprising a plurality of nanoparticles crosslinked to a gel comprising a mixture of polymers of varying flexibility, said nanoparticles comprising a core and an outer shell, wherein said core and said outer shell have compositions which are different and chosen such that the composite nanoparticle exhibits a buffered temperature dependency with respect to at least one physical property, said physical property selected from the group consisting of refractive index, magnetism, and electrical conductivity, and combinations thereof. 
     
     
         15 . The thin film coating of  claim 14  prepared as an indexable thin film by site selective binding of the nanoparticles to a lithographically etched or printed plate and overcoating with a polymer protective coating. 
     
     
         16 . The thin film coating of  claim 14 , wherein the gel comprises a mixture of inorganic and organic polymers of varying magnetic dipole strength and conductivity. 
     
     
         17 . The thin film coating of  claim 14 , wherein the gel is formed in the presence of a magnetic or electric field gradient such that the buffered temperature dependency is a gradient. 
     
     
         18 . The thin film coating of  claim 14 , wherein the plurality of nanoparticles vary in composition so as to form a gradient in temperature dependency across the thin film. 
     
     
         19 . A method of making a nanocomposite thin film coating, comprising:
 forming a plurality of solid layered composite nanoparticles having properties with reduced temperature dependency, said forming a plurality of nanoparticles comprising:
 providing a core particle; 
 forming an outer shell having one or more layers, 
 wherein said core and said outer shell have compositions which are different and chosen such that the composite nanoparticle exhibits a buffered temperature dependency with respect to at least one physical property selected from the group consisting of refractive index, magnetism, electrical conductivity, and combinations thereof 
   forming a gel including a mixture of inorganic and organic polymers of varying mechanical flexibility;   crosslinking the plurality of nanoparticles with the gel to form a nanoparticle gel;   forming the nanocomposite thin film of the nanoparticle gel by coating an object.   
     
     
         20 . The method of  claim 19 , further comprising mixing at least two composite nanoparticle collections of the solid layered composite nanoparticles, each having a different composition from the other so as to achieve a target physical property. 
     
     
         21 . The method of  claim 19 , wherein the thin film is formed by a liquid phase deposition or vapor phase deposition process. 
     
     
         22 . The method of  claim 19 , wherein the thin film is formed by spin coating. 
     
     
         23 . The method of  claim 19 , wherein the thin film is formed by site selective binding of the nanoparticles to a lithographically etched or printed plate and overcoating with inorganic or organic polymer protective coating. 
     
     
         24 . A nanocomposite optical probe, comprising a plurality of nanoparticles embedded in an optical probe matrix having a tapered tip, said nanoparticles comprising a core and an outer shell, wherein said core and said outer shell have compositions which are different and chosen such that the composite nanoparticle exhibits a buffered temperature dependency with respect to at least one physical property, said physical property selected from the group consisting of refractive index, magnetism, and electrical conductivity, and combinations thereof. 
     
     
         25 . The optical probe of  claim 24 , wherein the outer shell includes multiple layers having different compositions. 
     
     
         26 . The optical probe of  claim 24 , wherein the optical probe is an optical NSOM fiber. 
     
     
         27 . The optical probe of  claim 24 , wherein the plurality of nanoparticles exhibit a dη/dT gradient across the optical probe, sufficient to produce a buffered temperature having a lower dη/dT at the tapered tip than remote from the tapered tip.