A reaction product, which is an ethylenically unsaturated polyurethane oligomer or polymer, wherein said reaction product results from the reaction of: A) an alcohol component comprising: A1) at least one hydroxylated and optionally alkoxylated hydroxylated polydiene oligomer or polymer, in particular diol, optionally said polydiene being hydrogenated; and A2) at least one hydroxyl-functional, particularly hydroxyl monofunctional, ethylenically unsaturated compound, which is a monomer or oligomer, bearing at least one ethylenic unsaturation, preferably at least one (meth)acrylate; and B) an isocyanate component comprising at least one polyisocyanate with a functionality of at least 2, wherein the molar ratio OH/NCO is greater than 1.05; wherein said reaction product is comprised of an ethylenically unsaturated polyurethane oligomer or polymer, which is bearing one or more reactive free hydroxyl groups per chain and one or more ethylenic unsaturations derived from A2), per chain,, wherein said ethylenically unsaturated polyurethane oligomer or polymer is represented by the following Formula: X 1 -O-R 1 -O-[-C(=O)-NH-R 2 -NH-C(=O)-O-R 3 -O-] n -X 2 wherein X 1 and X 2 are each independently H or -C(=O)-NH-R 4 -NH-C(=O)-O-R 5 -[O-C(=O)-C(R 6)=CH 2] m, subject to the proviso that at least one of X 1 and X 2 is H; n is an integer of from 1 to 20, more preferably from 1 to 10; m can vary from 1 to 5; R 1 and R 3 are each independently a polydiene segment, an alkoxylated polydiene segment or a polyoxyalkylene segment, subject to the proviso that at least one of R 1 or R 3 is a polydiene segment or an alkoxylated polydiene segment, optionally with hydrogenated said polydiene segment; R 2 and R 4 are each independently an organo residue of a diisocyanate; R 5 is C 2 to C 10 alkylene or dialkylene ether and R 6 is H or methyl, with an OH value between 1.01 and 20 mg KOH/g and with a number average molecular weight Mn in the range from 1000 to 100000 Daltons and wherein at least 75% of the R 1 and R 3 segments are polydiene and/or alkoxylated polydiene segments. A) an alcohol component comprising: A1) at least one hydroxylated and optionally alkoxylated hydroxylated polydiene oligomer or polymer, in particular diol, optionally said polydiene being hydrogenated; and A2) at least one hydroxyl-functional, particularly hydroxyl monofunctional, ethylenically unsaturated compound, which is a monomer or oligomer, bearing at least one ethylenic unsaturation, preferably at least one (meth)acrylate; and A1) at least one hydroxylated and optionally alkoxylated hydroxylated polydiene oligomer or polymer, in particular diol, optionally said polydiene being hydrogenated; and A2) at least one hydroxyl-functional, particularly hydroxyl monofunctional, ethylenically unsaturated compound, which is a monomer or oligomer, bearing at least one ethylenic unsaturation, preferably at least one (meth)acrylate; and B) an isocyanate component comprising at least one polyisocyanate with a functionality of at least 2, wherein the molar ratio OH/NCO is greater than 1.05; X 1 and X 2 are each independently H or -C(=O)-NH-R 4 -NH-C(=O)-O-R 5 -[O-C(=O)-C(R 6)=CH 2] m, subject to the proviso that at least one of X 1 and X 2 is H; n is an integer of from 1 to 20, more preferably from 1 to 10; m can vary from 1 to 5; R 1 and R 3 are each independently a polydiene segment, an alkoxylated polydiene segment or a polyoxyalkylene segment, subject to the proviso that at least one of R 1 or R 3 is a polydiene segment or an alkoxylated polydiene segment, optionally with hydrogenated said polydiene segment; R 2 and R 4 are each independently an organo residue of a diisocyanate; R 5 is C 2 to C 10 alkylene or dialkylene ether and R 6 is H or methyl, with an OH value between 1.01 and 20 mg KOH/g and with a number average molecular weight Mn in the range from 1000 to 100000 Daltons and wherein at least 75% of the R 1 and R 3 segments are polydiene and/or alkoxylated polydiene segments.