Crosslinking in emulsion polymerization

In a process for the production of a copolymer from a mixture of monomers wherein at least one monomer is a conjugated alkadiene having 4 to 8 carbon atoms and at least one other monomer of said mixture is a vinyl-substituted aromatic monomer having 6 to 10 carbon atoms or for the production of a polymer of at least one conjugated alkadiene having 4 to 8 carbon atoms by emulsion polymerization wherein said polymerization is carried out under polymerization conditions in the presence of a polymerization initiator, the improvement which comprises carrying out the emulsion polymerization step in the presence of diisoprenyl ether, said ether having the formula ##STR3## and being incorporated in an amount sufficient to effect crosslinking of the polymer in said polymerization emulsion.