Polymeric-inorganic particles useful as lubricant additives

A polymeric-inorganic nanoparticle, comprising one inorganic nanoparticle covalently bonded to one or more polymers, each polymer comprising:

• a) units derived from at least one compound of formula (I):
• and
• b) units derived from at least one alkyl (meth)acrylate, wherein the alkyl group of the alkyl (meth)acrylate comprises from 1 to 40 carbon atoms,
• wherein:
• at least two units a) of each polymer are covalently bonded to the inorganic nanoparticle;
• R is H or CH3;
• Si(A)h(X)3−h is a silane functional group, where 0≤h≤2;
• A is a branched or unbranched C1 to C4 alkyl residue;
• B is a branched or unbranched, aliphatic, aromatic or mixed aliphatic-aromatic C1 to C30 carbon-based group;
• X is selected from H, Cl or a group OY, wherein Y is H or a C to C30 branched or unbranched alkyl-, alkenyl-, aryl-, or aralkyl- group, branched or unbranched C2 to C30 alkylether-group or branched or unbranched C2 to C30 alkylpolyether-group or a mixture thereof;
• and
• the units b) derived from the at least one alkyl (meth)acrylate are selected from the group consisting of:
• (b1) 0 to 30% by weight of units derived from at least one alkyl (meth)acrylate monomer of formula (II), based on the total weight of the monomer composition:
• where R is hydrogen or methyl, and R1 is a linear, branched or cyclic alkyl residue with 1 to 8 carbon atoms,
• (b2) 0 to 99.9% by weight of units derived from at least one alkyl (meth)acrylate monomer of formula based on the total weight of the monomer composition:
• where R is hydrogen or methyl, and R2 is a linear, branched or cyclic alkyl residue with 9 to 15 carbon atoms, and
• (b3) 0 to 99.9% by weight of units derived from at least one alkyl (meth)acrylate monomer of formula (IV), based on the total weight of the monomer composition:
• where R is hydrogen or methyl, and R3 is a linear, branched or cyclic alkyl residue with 16 to 40 carbon atoms,
• wherein:
• each polymer comprises at least 10% by weight of either monomer units b2) or b3) or a mixture of both, based on the total weight of the monomer composition;
• and
• the amounts of monomers a), b1), b2) and b3) are selected to sum up to 100% by weight of the mixture of monomers a), b1), b2) and b3).