A polymer nanoparticle is provided. The nanoparticle includes an inner
layer having alkenylbenzene monomer units. The nanoparticle further
includes an outer layer having monomer units selected from conjugated
dienes, alkylenes, alkenylbenzenes, and mixtures thereof. The
nanoparticle has at least one functional group associated with the outer
layer. Applications of use as additives for rubber, including the rubber
compositions, are also provided.