Synthesis, capping and dispersion of nanocrystals

Abstract

Preparation of semiconductor nanocrystals and their dispersions in solvents and other media is described. The nanocrystals described herein have small (1-10 nm) particle size with minimal aggregation and can be synthesized with high yield. The capping agents on the as-synthesized nanocrystals as well as nanocrystals which have undergone cap exchange reactions result in the formation of stable suspensions in polar and nonpolar solvents which may then result in the formation of high quality nanocomposite films.

1 . Nanocrystals formed by a solvothermal method, said method comprising
 dissolving or mixing at least one precursor of said nanocrystals in at least one solvent to produce a solution,   heating said solution to a temperature in the range of greater than a temperature of 250° C. to a temperature of 350° C. and a pressure in the range of 100-900 psi to form said nanocrystals,   wherein   said nanocrystals are comprised of at least one of hafnium oxide, zirconium oxide, hafnium-zirconium oxide and titanium-zirconium oxide.   
     
     
         2 . The nanocrystals of  claim 1  wherein said at least one precursor is selected from the group consisting of at least one of an alkoxide, an acetate, an acetylacetonate, and a halide. 
     
     
         3 . The nanocrystals of  claim 1  wherein said pressure is in the range of 100-500 psi. 
     
     
         4 . The nanocrystals of  claim 3  wherein said temperature is in the range of 300-350° C. 
     
     
         5 . The nanocrystals of  claim 4  wherein said heating comprises heating for 1-2 hours. 
     
     
         6 . The nanocrystals of  claim 1  wherein said nanocrystals are capped with at least one agent to increase the solubility or dispersibility of said nanocrystals. 
     
     
         7 . The nanocrystals of  claim 6  wherein said at least one agent comprises at least one organosilane, organocarboxylic acid or organoalcohol. 
     
     
         8 . The nanocrystals of  claim 6  wherein said at least one agent to cap said nanocrystals is included in the solution. 
     
     
         9 . The nanocrystals of  claim 8  wherein said at least one agent to cap said nanocrystals is contacted with said solution prior, during or after said reacting. 
     
     
         10 . The nanocrystals of  claim 1  further comprising purifying and/or separating said nanocrystals. 
     
     
         11 . The nanocrystals of  claim 10  further comprising capping said purified and/or separated nanocrystals with at least one capping agent to produce at least partially capped nanocrystals. 
     
     
         12 . The nanocrystals of  claim 6  further comprising purifying and/or separating said at least partially capped nanocrystals. 
     
     
         13 . The nanocrystals of  claim 10  further comprising contacting said purified and/or separated nanocrystals with a solvent. 
     
     
         14 . The nanocrystals of  claim 12  further comprising contacting said at least partially capped nanocrystals with a solvent. 
     
     
         15 . The nanocrystals of  claim 10  wherein said nanocrystals are dispersed in a further material. 
     
     
         16 . The nanocrystals of  claim 15  wherein said further material is a polymer. 
     
     
         17 . A film or coating formed by a method comprising dispersing the nanocrystals of  claim 1  in at least one further material to form a dispersion and applying said dispersion to a surface. 
     
     
         18 . A film or coating formed by a method comprising dispersing the nanocrystals of  claim 2  in at least one further material to form a dispersion and applying said dispersion to a surface. 
     
     
         19 . A film or coating formed by a method comprising dispersing the nanocrystals of  claim 6  in at least one further material to form a dispersion and applying said dispersion to a surface. 
     
     
         20 . The film or coating of  claim 17  wherein said applying comprises spin coating, spraying, dipping, screen printing, rolling, painting, printing, ink jet printing, depositing by evaporation and/or vapor deposition. 
     
     
         21 . A nanocomposite formed by a method comprising combining the nanocrystals of  claim 1  with at least one further material and forming the nanocomposite. 
     
     
         22 . The nanocrystals of  claim 1  wherein said at least one solvent comprises benzyl alcohol, phenol, oleyl alcohol, toluene, butanol, propanol, isopropanol, ethanol, methanol, propylene glycol monomethyl ether (PGME), propylene glycol methyl ether acetate (PGMEA), ethyl lactate (EL), and 2-propoxy-propanol (PnP), acetonitrile, acetone, tetrahydrofuran, cyclic ketones and mixtures thereof. 
     
     
         23 . The nanocrystals of  claim 6  wherein said at least one agent comprises at least one of n-propyltrimethoxysilane, n-propyltriethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, phenyltrimethoxysilane, 2-[methoxy(polyethyleneoxy)propyl]-trimethoxysilane, methoxytri(ethyleneoxy)propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-(methacryloyloxy)propyl trimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, and glycidoxypropyltrimethoxysilane, heptanol, hexanol, octanol, benzyl alcohol, phenol, ethanol, propanol, butanol, oleylalcohol, dodecylalcohol, octadecanol and triethylene glycol monomethyl ether, octanoic acid, acetic acid, propionic acid, 2-[2-(2-methoxyethoxy)ethoxy] acetic acid, oleic acid, benzoic acid or a mixture thereof. 
     
     
         24 . The nanocrystals of  claim 15  wherein said further material comprises a fluoroplastic, a polyacrylate (Acrylic), a polyamide (PA or Nylon), a polyamide-imide (PAI), a polyketone (PK), a polyester, a polyimide (PI), a polysulfone (PSU), a polyurethane (PU), a spin-on-glass (SOG) polymer, a silicone, or mixtures thereof. 
     
     
         25 . The nanocrystals of  claim 1  wherein water is present in said solution at a molar ratio of water to precursor in a range from 1:1 to 4:1. 
     
     
         26 . The nanocrystals of  claim 25  wherein said nanocrystals are in the average size range of 1 nm to 5 nm. 
     
     
         27 . The nanocrystals of  claim 13  wherein said solvent comprises benzyl alcohol, phenol, oleyl alcohol, toluene, butanol, propanol, isopropanol, ethanol, methanol, propylene glycol monomethyl ether (PGME), propylene glycol methyl ether acetate (PGMEA), ethyl lactate (EL), and 2-propoxy-propanol (PnP), acetonitrile, acetone, tetrahydrofuran, cyclic ketones and mixtures thereof. 
     
     
         28 . The nanocrystals of  claim 14  wherein solvent comprises benzyl alcohol, phenol, oleyl alcohol, toluene, butanol, propanol, isopropanol, ethanol, methanol, propylene glycol monomethyl ether (PGME), propylene glycol methyl ether acetate (PGMEA), ethyl lactate (EL), and 2-propoxy-propanol (PnP), acetonitrile, acetone, tetrahydrofuran, cyclic ketones and mixtures thereof. 
     
     
         29 . The nanocrystals of  claim 15  wherein said further material comprises poly(acrylonitrile-butadiene-styrene) (ABS), poly(methyl methacrylate) (PMMA), celluloid, cellulose acetate, poly(ethylene-vinyl acetate) (EVA), poly(ethylene vinyl alcohol) (EVOH), polyacrylonitrile (PAN), polyaryletherketone (PAEK), polybutadiene (PBD), polybutylene (PB), polybutylene terephthalate (PBT), polycaprolactone (PCL), polychlorotrifluoroethylene (PCTFE), polyethylene terephthalate (PET), polycyclohexylene dimethylene terephthalate (PCT), polycarbonate (PC), polyhydroxyalkanoates (PHAs), polyethylene (PE), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherimide (PEI), polyethersulfone (PES), polyethylenechlorinates (PEC) , polylactic acid (PLA), polymethylpentene (PMP), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyphthalamide (PPA), polypropylene (PP), polystyrene (PS), polytrimethylene terephthalate (PTT), polyvinyl acetate (PVA), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), poly(styrene-acrylonitrile) (SAN), a siloxane-spin-on polymer, polydimethylsiloxane (PDMS) or polymethylphenylsiloxane, or mixtures thereof.