Branched polymers as viscosity and/or friction modifiers for lubricants

Abstract

Embodiments of branched polymer lubricant additives comprise a branched polymer and, when combined with a lubricant base at a concentration from 1 wt % to 50 wt %, provide (i) a viscosity index ≧150, (ii) that is at least 10% less than a coefficient of friction of the lubricant base alone in contact with a component of a device during operation of the device at a temperature within a range of 20 to 100° C., or (iii) both (i) and (ii).

We claim: 
     
         1 . A branched polymer, comprising:
 (a) a hyperbranched polar core having a functionality of at least 3 and comprising a plurality of heteroatoms, and a plurality of polymeric or non-polymeric arms bonded to the hyperbranched polar core, wherein when the functionality is within a range of 3-21 and the plurality of arms is polymeric, the hyperbranched polar core is not a cyclotetrasiloxane derivative, a cyclophosphazene derivative, a calixarene derivative, a cyclodextrin derivative, or a saccharide derivative;   (b) an aryl polyester core derived from AB x  monomers, AB x +B y  monomers, or A 2 +B y  monomers, where x≧2 and y≧3, the aryl polyester core having a degree of branching within a range of 0.1 to 0.9, and a plurality of polymeric or non-polymeric arms bonded to the aryl polyester core; or   (c) a branched polyolefin including first monomeric units derived from an olefin and second monomeric units derived from polar monomers, each polar monomer including at least one heteroatom, wherein when the olefin is ethylene, the polar monomers are not an alkenyl ether, methyl-9-decenoate, or methyl 2,2-dimethylpent-4-enoate.   
     
     
         2 . The branched polymer of  claim 1 , wherein the branched polymer comprises a hyperbranched polar core derived from:
 a branched 2,2-bis(hydroxymethyl)propionic acid polyester comprising 8-256 hydroxy moieties;   a branched polyethyleneimine comprising primary, secondary, and tertiary amine groups and having an weight average molecular weight within a range of 600-10,000 Daltons; or   a branched polyamidoamine comprising 8-256 primary amine moieties.   
     
     
         3 . The branched polymer of  claim 2 , wherein each of the plurality of arms is a non-polymeric arm derived from a C 8 -C 20  aliphatic carboxylic acid, a C 8 -C 20  aliphatic acyl halide, a C 8 -C 20  aliphatic ester, or a C 8 -C 20  aliphatic glycidyl ether. 
     
     
         4 . The branched polymer of  claim 2 , wherein each of the plurality of arms is a random copolymer or a block copolymer, the random or block copolymer comprising first monomeric units derived from nonpolar monomers and second monomeric units derived from polar monomers. 
     
     
         5 . The branched polymer of  claim 4 , wherein the nonpolar monomers are unsubstituted alkenes, aryl-substituted alkenes wherein the aryl group is alkyl-substituted or unsubstituted, alkyl acrylates wherein the alkyl group of the alkyl acrylate is unsubstituted and has 6 to 20 carbon atoms, methacrylates wherein the alkyl group of the alkyl methacrylate is unsubstituted and has 6 to 20 carbon atoms, lipophilic vinyl monomers, or a combination thereof. 
     
     
         6 . The branched polymer of  claim 4 , wherein each of the second monomeric units comprises at least one heteroatom. 
     
     
         7 . The branched polymer of  claim 4 , wherein the polar monomers are 
       
         
           
           
               
               
           
         
       
       where t is an integer from 1 to 10, or a combination thereof. 
     
     
         8 . The branched polymer of  claim 1 , wherein the branched polymer comprises:
 an aryl polyester core derived from AB 2  monomers having a structure   
       
         
           
           
               
               
           
         
       
       where n is an integer from 3 to 20, and the core has a degree of branching within a range of 0.1 to 0.9. 
     
     
         9 . The branched polymer of  claim 8 , comprising a plurality of non-polymeric arms having a structure 
       
         
           
           
               
               
           
         
       
       where q is an integer from 8 to 16. 
     
     
         10 . The branched polymer of  claim 9 , comprising a plurality of homopolymeric arms derived from a nonpolar monomer, wherein the nonpolar monomer is an unsubstituted alkene, an aryl-substituted alkene wherein the aryl group is alkyl-substituted or unsubstituted, an alkyl acrylate wherein the alkyl group of the alkyl acrylate is unsubstituted and has 6 to 20 carbon atoms, a methacrylate wherein the alkyl group of the alkyl methacrylate is unsubstituted and has 6 to 20 carbon atoms, or a lipophilic vinyl monomer. 
     
     
         11 . The branched polymer of  claim 9 , comprising a plurality of copolymeric arms comprising first monomeric units derived from nonpolar monomers and second monomeric units derived from polar monomers, each second monomeric unit comprising at least one heteroatom. 
     
     
         12 . The branched polymer of  claim 11 , wherein the first monomeric units are derived from ethylene and the second monomeric units are derived from polar monomers having a general formula R 1 —C(O)O—R 2 , wherein R 1  is an alkenyl moiety and R 2  is a C 1 -C 3  alkyl moiety or a heteroaliphatic moiety including at least one oxygen atom, at least one nitrogen atom, or at least one oxygen atom and at least one nitrogen atom. 
     
     
         13 . The branched polymer of  claim 12 , wherein the polar monomers are 
       
         
           
           
               
               
           
         
       
       where t is an integer from 1 to 10, or a combination thereof. 
     
     
         14 . The branched polymer of  claim 1 , wherein the branched polymer is a branched polyolefin and the polar monomers comprise vinyl monomers, acrylate monomers, methacrylate monomers, or a combination thereof. 
     
     
         15 . A lubricant, comprising:
 a lubricant base; and   a branched polymer that, when combined with a lubricant base at a concentration from 1 wt % to 50 wt %, (i) provides a viscosity index 150, (ii) has a coefficient of friction that is at least 10% less than a coefficient of friction of the lubricant base alone in contact with a component of a device during operation of the device at a temperature within a range of 20 to 100° C., or (iii) both (i) and (ii), wherein the branched polymer is
 (a) a branched polymer comprising (i) a hyperbranched polar core having a functionality of at least 3 and comprising a plurality of heteroatoms, and (ii) a plurality of polymeric or non-polymeric arms bonded to the hyperbranched polar core, wherein when the functionality is within a range of 3-21 and the plurality of arms is polymeric, the hyperbranched polar core is not a cyclotetrasiloxane derivative, a cyclophosphazene derivative, a calixarene derivative, a cyclodextrin derivative, or a saccharide derivative; 
 (b) a branched polymer comprising an aryl polyester core derived from AB x  monomers, AB x +B y  monomers, or A 2 +B y  monomers, where x≧2 and y≧3, the aryl polyester core having a degree of branching within a range of 0.1 to 0.9, and a plurality of polymeric or non-polymeric arms bonded to the aryl polyester core; or 
 (c) a branched polyolefin comprising first monomeric units derived from an olefin and second monomeric units derived from a polar monomer including at least one heteroatom. 
   
     
     
         16 . The lubricant of  claim 15 , comprising 1 to 50 wt % of the branched polymer. 
     
     
         17 . The lubricant of  claim 15 , wherein the lubricant base is a group I oil, group II oil, a group III oil, a group IV oil, a group V oil, or any combination thereof. 
     
     
         18 . A method for making a lubricant, comprising:
 combining a lubricant base with a branched polymer to form a lubricant having (i) a viscosity index ≧150, (ii) has a coefficient of friction that is at least 10% less than a coefficient of friction of the lubricant base alone in contact with a component of a device during operation of the device at a temperature within a range of 20 to 100° C., or (iii) both (i) and (ii), wherein the branched polymer is
 (a) a hyperbranched polymer comprising (i) a hyperbranched polar core having a functionality of at least 3 and comprising a plurality of heteroatoms, and (ii) a plurality of polymeric or non-polymeric arms bonded to the hyperbranched polar core, wherein when the functionality is within a range of 3-21 and the plurality of arms is polymeric, the hyperbranched polar core is not a cyclotetrasiloxane derivative, a cyclophosphazene derivative, a calixarene derivative, a cyclodextrin derivative, or a saccharide derivative; 
 (b) a branched polymer comprising an aryl polyester core derived from AB x  monomers, AB x +B y  monomers, or A 2 +B y  monomers, where x≧2 and y≧3, the aryl polyester core having a degree of branching within a range of 0.1 to 0.9, and a plurality of polymeric or non-polymeric arms bonded to the aryl polyester core; or 
 a branched polyolefin comprising first monomeric units derived from an olefin and second monomeric units derived from a polar monomer including at least one heteroatom. 
   
     
     
         19 . The method of  claim 18 , wherein the lubricant has a concentration of the branched polymer within a range of 1-50 wt %. 
     
     
         20 . A method for lubricating an engine, comprising supplying to the engine a lubricant according to  claim 15 .