Materials having structure (1), wherein R and R.sup.1 may be the same or different and each independently represents an alkyl or aryl group, X may be hydrogen or a C.sub.1 to C.sub.20 alkyl group which may be branched or linear and wherein the aromatic ring substituent joined to polymer B is positioned meta or para to the aromatic ring substituent joined to polymer A and, wherein polymer A is a non-polar polymer formed by metallocene catalysis and polymer B is a polymer formed by radical catalysis of a polar monomer are used as polymer additives particularly to improve the compatibility of mixtures of polymers.

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A foam is obtained by foaming a resin composition, which comprises a hydroxyl-terminated hydrogenated styrenic block copolymer of (A-B)n-OH, (B-A)n-OH, A(B-A)n-OH, or B(A-B)n-OH having a hydroxyl group at the terminal; wherein the A block comprises a styrene monomer unit and the B block comprises a conjugated diene monomer unit; wherein the hydroxyl-terminated hydrogenated styrenic block copolymer comprises 1060% by weight of the styrene monomer unit; 40 mol % or more of the conjugated diene monomer unit is hydrogenated; and the hydrogenated styrenic block copolymer has a weight average molecular weight of about 30000 to about 200000; the 1,2-vinyl bond content in the conjugated diene monomer unit of the hydroxyl-terminated hydrogenated styrenic block copolymer is in the range of 5 to 60 mole % prior to hydrogenation.

A method comprising providing a polymer latex comprising particles of polymer in aqueous dispersion, adding a peroxide in an amount of 0.005 to 5, preferably 0.01 to 4, parts by weight peroxide per 100 parts by weight of dried polymer to the polymer latex at a pH of at least 8.5, preferably at least 9, and, after the contacting, coagulating the polymer latex.