One-pot synthesis of nanoparticles and liquid polymer for rubber applications

Abstract

A method for performing a one-pot synthesis of a blend of nanoparticles and liquid polymer includes polymerizing a first monomer and optionally a second monomer in a hydrocarbon solvent to form the liquid polymer. The polymerization is terminated before completion with a quenching agent. Then a charge of polymerization initiator, and a mixture of cross-linking agent and mono-vinyl aromatic monomer are added. This causes further polymerization whereby nanoparticles are formed having a core including the cross-linking agent, and a shell including the first monomer or the first monomer and the second monomer. Nanoparticle/liquid polymer blends resulting from the method and rubber compositions incorporating the blends are also disclosed.

1 . A method for preparing a one-pot synthesized blend of nanoparticles and liquid polymer in a solvent, the method comprising the steps of:
 (a) in a reaction vessel, polymerizing either a first monomer to form a liquid polymer, or copolymerizing the first monomer and a second monomer to form the liquid polymer;   (b) partially terminating the polymerization with a quenching agent; and   (c) adding a polyfunctional comonomer, a mono-vinyl aromatic monomer, and an optional charge of polymerization initiator;   wherein said nanoparticles have a core including the mono-vinyl aromatic monomer and a shell comprising the first monomer or the first and the second monomer.   
     
     
         2 . The method of  claim 1 , wherein the quenching agent partially terminates the polymerization such that 20 to 95% of the polymers chains are terminated. 
     
     
         3 . The method of  claim 1 , further comprising the step of filtering and drum drying the one-pot synthesized blend of nanoparticles and liquid polymer. 
     
     
         4 . The method of  claim 1 , wherein the second monomer is selected from the group consisting of styrene, α-methyl styrene, 1-vinyl naphthalene, 2-vinyl naphthalene, 1-α-methyl vinyl naphthalene, 2-α-methyl vinyl naphthalene, vinyl toluene, methoxystyrene, t-butoxystyrene, and alkyl, cycloalkyl, aryl, alkaryl, and aralkyl derivatives thereof in which the total number of carbon atoms in the derivative is not greater than 18, or any di- or tri-substituted aromatic hydrocarbons, and mixtures thereof. 
     
     
         5 . The method of  claim 1 , wherein the first monomer is a conjugated diene. 
     
     
         6 . The method of  claim 5 , wherein the first monomer is selected from the group consisting of C 4 -C 8  conjugated dienes and mixtures thereof. 
     
     
         7 . The method of  claim 1 , wherein the nanoparticles are crosslinked with the polyfunctional comonomer. 
     
     
         8 . The method of  claim 1 , wherein the cross-linking agent is selected from the group consisting of diisopropenylbenzene, divinylbenzene, divinyl ether, divinyl sulphone, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, 1,2-polybutadiene, N,N′-m-phenylenedimaleimide, N,N′-(4-methyl-m-phenylene)dimaleimide and/or triallyl trimellitate. acrylates and methacrylates of polyhydric, C 2 -C 10  alcohols, acrylates and methacrylates of polyethylene glycol having from 2 to 20 oxyethylene units and polyesters composed of aliphatic di- and/or polyols, or maleic acid, fumaric acid and/or itaconic acid. 
     
     
         9 . The method of  claim 8 , wherein the cross-linking agent is divinylbenzene. 
     
     
         10 . The method of  claim 1 , wherein the first monomer is butadiene and the second monomer is styrene. 
     
     
         11 . The method of  claim 1 , wherein the core of the nanoparticle has a Tg of about 60° C. or higher. 
     
     
         12 . The method of  claim 1 , wherein the shell of the nanoparticle has a Tg lower than about 0° C. 
     
     
         13 . The method of  claim 1 , wherein the shell of the nanoparticle has a Tg between about 0° C. and about −70° C. 
     
     
         14 . The method of  claim 1 , wherein the core of the nanoparticle has a Tg of at least about 60° C. higher than the Tg of the shell. 
     
     
         15 . The method of  claim 1 , wherein the liquid polymer has an Mw of about 10,000 to about 120,000. 
     
     
         16 . The method of  claim 1 , wherein the nanoparticles are formed by micelle self-assembly. 
     
     
         17 . The method of  claim 15 , wherein the nanoparticles have a core comprising styrene cross-linked with divinylbenzene and a shell comprising butadiene. 
     
     
         18 . The method of  claim 1 , wherein the cross-linking agent is added before the polymerization initiator and mono-vinyl aromatic monomer. 
     
     
         19 . The method of  claim 1 , wherein the quenching agent is selected from the group consisting of methanol, ethanol, propanol, and isopropanol. 
     
     
         20 . The method of  claim 1 , wherein the quenching agent is a functionalizing agent. 
     
     
         21 . The method of  claim 20 , wherein the functionalizing agent is tin tetrachloride. 
     
     
         22 . The method of  claim 1 , wherein the polymerizing or copolymerizing of step (a) are initiated with an anionic initiator. 
     
     
         23 . The method of  claim 1 , wherein the steps are performed in the same reaction vessel. 
     
     
         24 . A method for making a rubber composition, the method comprising:
 making a blend of nanoparticles and liquid polymer according of  claim 1 ; and   adding the blend to a rubber composition.   
     
     
         25 . A method for making a tire with nanoparticles and liquid polymer, the method comprising:
 making a blend of nanoparticles and liquid polymer according to  claim 1 ;   adding the blend to a rubber composition;   molding the rubber composition into a tire tread; and   constructing a tire using the tire tread.   
     
     
         26 . A composition of matter consisting essentially of:
 core-shell type, micellar nanoparticles; and   a liquid polymer having a Mw of about 10,000 to about 120,000;   wherein the nanoparticles are dispersed and blended within the liquid polymer.   
     
     
         27 . The composition of matter of  claim 26 , wherein the nanoparticles and liquid polymer are present in a ratio of 25:75 to 40:60.