Organic-inorganic composite particles, dispersion and resin composition comprising the same, and method for producing organic-inorganic composite particles

Abstract

Organic-inorganic composite particles including: inorganic particles; and an organic polymer, wherein the inorganic particles have surfaces on which no modification treatment for introducing a polymerizable reactive group is conducted, the organic polymer comprises a hydrophilic block arranged on the surfaces of the inorganic particles and made of a first polymer, and a hydrophobic block stacked on an outside of the hydrophilic block and made of a second polymer, and the inorganic particles, the first polymer, and the second polymer have surface free energies satisfying a condition expressed by the following formula: E NP >E A >E B [in the formula, E NP represents the surface free energy of the inorganic particles, E A represents the surface free energy of the first polymer, and E B represents the surface free energy of the second polymer].

1 . Organic-inorganic composite particles,
 comprising: inorganic particles and an organic polymer, wherein   the inorganic particles have surfaces on which no modification treatment for introducing a polymerizable reactive group is conducted,   the organic polymer comprises a hydrophilic block arranged on the surfaces of the inorganic particles and made of a first polymer, and a hydrophobic block stacked on an outside of the hydrophilic block and made of a second polymer, and   the inorganic particles, the first polymer, and the second polymer have surface free energies satisfying a condition expressed by the following formula (1):
   E NP >E A >E B   (1)
 
   
       [in the formula (1), E NP  represents the surface free energy of the inorganic particles, E A  represents the surface free energy of the first polymer, and E B  represents the surface free energy of the second polymer; and
 obtained by a method comprising: 
 a first polymerization step of obtaining the hydrophilic block made of a first polymer by conducting a living radical polymerization of a first monomer in a reaction solution containing the inorganic particles, the first monomer, and a solvent, without conducting a modification treatment for introducing a polymerizable reactive group on surfaces of the inorganic particles, and allowing the first polymer thus obtained to be adsorbed on the surfaces of the inorganic particles, and 
 a second polymerization step of obtaining the hydrophobic block made of a second polymer by adding a second monomer to the reaction solution after the first polymerization step, conducting a living radical polymerization of the second monomer, and polymerizing the second polymer thus obtained onto growing ends of the first polymer, to stack the second polymer on an outside of the hydrophilic block, wherein 
 the inorganic particles, the first polymer, the second polymer, and the solvent have surface free energies satisfying a condition expressed by the following formula (2):
   E NP >E A >E B >E S   (2)
 
 
 
       [in the formula (2), E NP  represents the surface free energy of the inorganic particles, E A  represents the surface free energy of the first polymer, E B  represents the surface free energy of the second polymer, and E S  represents the surface free energy of the solvent]. 
     
     
         2 . The organic-inorganic composite particles according to  claim 1 , wherein
 a content of the organic polymer per unit surface area of the inorganic particles is 0.0005 to 1.0 chains/nm 2 .   
     
     
         3 . The organic-inorganic composite particles according to  claim 1 , wherein
 a mass ratio between the first polymer and the second polymer (a mass of the first polymer:a mass of the second polymer) is 1:1 to 1:500.   
     
     
         4 . The organic-inorganic composite particles according to  claim 1 , wherein
 the organic polymer has a number average molecular weight of 3,000 to 1,000,000 g/mol, and a molecular weight distribution (weight average molecular weight/number average molecular weight) of 1.05 to 2.0.   
     
     
         5 . The organic-inorganic composite particles according to  claim 1 , wherein
 the organic-inorganic composite particles have particle diameters of 1.6 to 10,000 nm.   
     
     
         6 . A dispersion, comprising:
 the organic-inorganic composite particles according to  claim 1 ; and   a solvent.   
     
     
         7 . A resin composition, comprising:
 the organic-inorganic composite particles according to  claim 1 , and   a resin.   
     
     
         8 . A method for producing organic-inorganic composite particles comprising inorganic particles and an organic polymer, the method comprising:
 a first polymerization step of obtaining a hydrophilic block made of a first polymer by conducting a living radical polymerization of a first monomer in a reaction solution containing the inorganic particles, the first monomer, and a solvent, without conducting a modification treatment for introducing a polymerizable reactive group on surfaces of the inorganic particles, and allowing the first polymer thus obtained to be adsorbed on the surfaces of the inorganic particles; and   a second polymerization step of obtaining a hydrophobic block made of a second polymer by adding a second monomer to the reaction solution after the first polymerization step, conducting a living radical polymerization of the second monomer, and polymerizing the second polymer thus obtained onto growing ends of the first polymer, to stack the second polymer on an outside of the hydrophilic block, wherein   the inorganic particles, the first polymer, the second polymer, and the solvent have surface free energies satisfying a condition expressed by the following formula (2):
   E NP >E A >E B >E S   (2)
 
   
       [in the formula (2), E NP  represents the surface free energy of the inorganic particles, E A  represents the surface free energy of the first polymer, E B  represents the surface free energy of the second polymer, and E S  represents the surface free energy of the solvent]. 
     
     
         9 . Organic-inorganic composite particles, comprising:
 inorganic particles; and   an organic polymer, wherein   the inorganic particles have surfaces on which no modification treatment for introducing a polymerizable reactive group is conducted,   the organic polymer comprises a hydrophilic block arranged on the surfaces of the inorganic particles and made of a first polymer, and a hydrophobic block stacked on an outside of the hydrophilic block and made of a second polymer,   the inorganic particles, the first polymer, and the second polymer have surface free energies satisfying a condition expressed by the following formula (1):
   E NP >E A >E B   (1)
 
   
       [in the formula (1), E NP  represents the surface free energy of the inorganic particles, E A  represents the surface free energy of the first polymer, and E B  represents the surface free energy of the second polymer, and
 a content of the organic polymer per unit surface area of the inorganic particles is 0.0005 to 1.0 chains/nm 2 .