Organically modified fine particles

Abstract

A technique for bonding an organic group with the surface of fine particles such as nanoparticles through strong linkage is provided, whereas such fine particles are attracting attention as materials essential for development of high-tech products because of various unique excellent characteristics and functions thereof. Organically modified metal oxide fine particles can be obtained by adapting high-temperature, high-pressure water as a reaction field to bond an organic matter with the surface of metal oxide fine particles through strong linkage. The use of the same condition enables not only the formation of metal oxide fine particles but also the organic modification of the formed fine particles. The resulting organically modified metal oxide fine particles exhibit excellent properties, characteristics and functions.

We claim: 
     
         1 . A process for producing organically modified metal oxide nanoparticles, which comprises:
 reacting an organic modifying agent with the surface of a metal oxide nanoparticle in a reaction field of high-temperature, high-pressure water to form organically modified metal oxide nanoparticles   wherein an optionally substituted or unsubstituted hydrocarbon group is bonded to the surface of each nanoparticle through a linkage selected from the group consisting of a covalent bond, an ether bond, an ester bond, a bond through an N atom, a bond through an S atom, a metal-C— bond, a metal-C═ bond, and a metal-(C═O)— bond.   
     
     
         2 . The process according to  claim 1 , wherein the high-temperature, high-pressure water is water under supercritical or subcritical conditions. 
     
     
         3 . The process according to  claim 1 , wherein the high-temperature, high-pressure water is water under conditions at the critical pressure or a pressure above the critical point and/or at the critical temperature or a temperature above the critical point. 
     
     
         4 . The process according to  claim 1 , wherein said organically modified metal oxide nanoparticles are formed in a reaction field where water is present under conditions at a temperature ranging from 250 to 500° C. and a pressure ranging from 10 to 30 MPa. 
     
     
         5 . The process according to  claim 1 , wherein said hydrocarbon group is a long-chain hydrocarbon group having a chain having 1, 2, 3 or more carbon atoms. 
     
     
         6 . The process according to  claim 1 , wherein said organic modifying agent is selected from the group other than an alkanethiol. 
     
     
         7 . The process according to  claim 1 , wherein said organic modifying agent is selected from the group consisting of an alcohol, an aldehyde, a carboxylic acid, an amine, a thiol, an amide, a ketone, an oxime, a phosgene, an enamine, an amino acid, a peptide and a sugar. 
     
     
         8 . The process according to  claim 1 , wherein said organic modifying agent is selected from the group consisting of an alcohol, an aldehyde, a carboxylic acid, an amine, an amide, a ketone, an oxime, a phosgene, an enamine, an amino acid, a peptide and a sugar. 
     
     
         9 . The process according to  claim 1 , wherein said metal oxide is an oxide of a metal element selected from the group consisting of elements of the group VIII, elements of the group IB, elements of the group IIB, elements of the group IIIB, elements of the group IVB, elements of the group VB, elements of the group VIB, and elements of the groups IA to VIIA, in the long-period periodic table. 
     
     
         10 . The process according to  claim 9 , wherein the metal element in said metal oxide is selected from the group consisting of Ti, Zr, Nb, Y, Eu, Mg, Ce, Ba, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, TI, Si, Ge, Sn, Pb, As, Sb, Bi, Te and Po. 
     
     
         11 . The process according to  claim 9 , wherein the metal element in said metal oxide is selected from the group consisting of Ti, Zr, Nb, Y, Eu, Mg, Ce, Ba, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, TI, Si, Ge, Sn, Pb, As, Sb, Bi, Te and Po. 
     
     
         12 . The process according to  claim 1 , wherein said metal oxide is an oxide of a metal element selected from the group consisting of elements of the group VIII, elements of the group IIB, elements of the group IIIB, elements of the group IVB, elements of the group VB, elements of the group VIB, and elements of the groups IA to VIIA, in the long-period periodic table. 
     
     
         13 . The process according to  claim 1 , wherein the reaction ratio of the organic modifying agent is regulated by controlling a factor selected from the group consisting of temperature, acid concentration and reaction time. 
     
     
         14 . The process according to  claim 1 , wherein said hydrocarbon group has a hydrophilic group and the products are organically modified metal oxide nanoparticles well dispersed in an aqueous solution. 
     
     
         15 . The process according to  claim 1 , wherein the average size of the nanoparticles is:
 (1) 100 nm or less;   (2) 50 nm or less;   (3) 20 nm or less;   (4) 10 nm or less; or   (5) 5 nm or less.   
     
     
         16 . The process according to  claim 1 , wherein the particle size of the generated particles is adjusted to a smaller particle size as compared with those where supercritical hydrothermal synthesis is performed in the absence of an organic modifying agent. 
     
     
         17 . The process according to  claim 1 , wherein said hydrocarbon group has a hydrophobic group and said organically modified metal oxide nanoparticles are well dispersible in an organic solvent phase, or can be transferred to the interface between an aqueous phase and an organic solvent phase. 
     
     
         18 . The process according to  claim 1 , wherein said metal oxide is selected from the group consisting of SiO 2 , SnO 2 , Al 2 O 3 , MnO 2 , NiO, Eu 2 O 3 , Y 2 O 3 , Nb 2 O 3 , InO, ZnO, Fe 2 O 3 , Fe 3 O 4 , Co 3 O 4 , ZrO 2 , CeO 2 , BaO.6Fe 2 O 3 , Al 5 (Y+Tb) 3 O 12 , BaTiO 3 , LiCoO 2 , LiMn 2 O 4 , K 2 O.6Ti O 2  and AlOOH. 
     
     
         19 . The process according to  claim 1 , wherein said metal oxide is selected from the group consisting of SiO 2 , Al 2 O 3 , MnO 2 , ZnO, CeO 2 , Fe 2 O 3 , Fe 3 O 4 , NiO, Co 2 O 3 , Co 3 O 4 , SnO 2 , Y 2 O 3 , InO, MgO, Nb 2 O 5 , Nb 2 O 3  and ZrO 2 . 
     
     
         20 . The process according to  claim 1 , wherein the particle size of product particles is evaluated by transmission electron microscopic (TEM) analysis. 
     
     
         21 . The process according to  claim 1 , wherein the state of bonding a substituted or unsubstituted hydrocarbon group to the surface of a metal oxide nanoparticle is verified by IR analysis and/or thermogravimetric analysis. 
     
     
         22 . The process according to  claim 1 , wherein said hydrocarbon group is a hydrocarbon group with a long-chain hydrocarbon group with a chain having 4 or more carbon atoms. 
     
     
         23 . A process for producing organically modified metal oxide nanoparticles, which comprises:
 reacting an organic modifying agent with the surface of a metal oxide nanoparticle in a reaction field of high-temperature, high-pressure water to form organically modified metal oxide nanoparticles   wherein an optionally substituted or unsubstituted hydrocarbon group is directly bonded to a surface of each metal oxide nanoparticle through a linkage from the hydrocarbon group selected from the group consisting of a covalent bond, an ether bond, an ester bond, a bond through an N atom, a bond through an S atom, a metal-C— bond, a metal-C═ bond, and a metal-(C—O)— bond, and said metal oxide is an oxide of a metal element selected from group consisting of an element of group VIII, an element of group IB, an element of group IIB, an element of group IIIB, an element of group IVB, an element of group VB, an element of group VIB, and an element of groups IA to VIIA, in the long-period periodic table, wherein the hydrocarbon group is strongly bonded to the surface of said metal oxide nanoparticle.   
     
     
         24 . The process according to  claim 23 , wherein said hydrocarbon group is a hydrocarbon group with a chain having 1, 2 or 3 carbon atoms, or a long-chain hydrocarbon group with a chain having 4 or more carbon atoms, or said hydrocarbon group is a substituted or unsubstituted straight-chain or branched-chain alkyl group. 
     
     
         25 . The process according to  claim 23 , wherein the metal element in said metal oxide is selected from the group consisting of Ti, Zr, Nb, Y, Eu, Mg, Ce, Ba, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Te and Po.