NOVELTY - Reaction product, preferably ethylenically unsaturated polyurethane, comprises: (A) alcohol component comprising (A1) hydroxylated and optionally alkoxylated hydroxylated polydiene oligomer or polymer, preferably diol, optionally polydiene is hydrogenated, and (A2) hydroxyl-functional, preferably hydroxyl monofunctional, ethylenically unsaturated compound, which is monomer or oligomer, bearing ethylenic unsaturation, preferably (meth)acrylate; and (B) isocyanate component comprising polyisocyanate with a functionality of at least 2, preferably 2.    USE - The reaction product is useful in coatings or adhesive compositions, for electronic devices or as a component in solar panels or as a component in battery or in inkjet printing microcircuits or in touch screen devices (claimed).    ADVANTAGE - The reaction product has greater compatibility with other ingredients typically found in adhesive formulations and deliver optical clarity, hence useful as coatings or adhesives for electronic devices, due to their enhanced optical clarity and excellent moisture resistance and also useful as a component of solar panels due to their low dielectric constant and high breakdown voltage.    DETAILED DESCRIPTION - Reaction product, preferably ethylenically unsaturated polyurethane, comprises: (A) an alcohol component comprising (A1) at least one hydroxylated and optionally alkoxylated hydroxylated polydiene oligomer or polymer, preferably diol, optionally the polydiene is hydrogenated, and (A2) at least one hydroxyl-functional, preferably 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, preferably 2, where the molar ratio of alcohol component/isocyanate component is greater than 1, and the reaction product comprising a polyurethane oligomer or polymer, preferably an ethylenically unsaturated oligomer or polymer, which is bearing at least one reactive free hydroxyl groups per chain and at least one ethylenic unsaturations derived from A2, per chain, preferably with a number average molecular weight of 1000-100000 Da. INDEPENDENT CLAIMS are also included for:    (1) an ethylenically unsaturated polyurethane polymer or oligomer of formula (X1-O-R1-O-(C(=O)-NH-R2-NH-C(=O)-O-R3-O)n-X2) (I);    (2) a polyurethane composition, comprising a polydiene (diol) urethane (meth)acrylate, preferably hydrogenated polybutadiene urethane (meth)acrylate, where at least one molecule of the polydiene urethane (meth)acrylate, preferably hydrogenated polybutadiene urethane (meth)acrylate, bears at least one terminal free hydroxyl group per chain, and the composition has an hydroxyl value 1.01 mg potassium hydroxide/g and 20 mg potassium hydroxide/g, the hydrogenated polybutadiene urethane (meth)acrylate has a number average molecular weight 1000-100000 Da;    (3) a curable composition comprising the reaction product, or the polyurethane polymer or oligomer, or the polyurethane composition;    (4) a material comprising the curable composition, where the material comprising coatings, preferably paints or varnishes or consisting of adhesives, sealants, caulks, graphic arts compositions, inks, flexographic printing plate compositions or encapsulant compositions; and    (5) making an ethylenically unsaturated polyurethane comprising reacting an alcohol component (A) with an isocyanate component (B), where the molar ratio of alcohol component/isocyanate component is greater than 1.    X1, X2 = H or -C(=O)-NH-R4-NH-C(=O)-O-R5-(O-C(=O)-C(R6)CH2)m,;    n = 1-20, preferably 1-10;    m = 1-5;    R1, R3 = polydiene segment, alkoxylated polydiene segment or polyoxyalkylene segment;    R2, R4 = organo residue of a diisocyanate;    R5 = 2-10C alkylene or dialkylene ether; and    R6 = H or methyl, with an OH value higher than 1 mg KOH/g, preferably 1.01-20 mg KOH/g and with a number average molecular weight of 1000-100000 Daltons.    Provided that: at least one of X1 and X2 is H; and at least one of R1 or R3 is polydiene segment or alkoxylated polydiene segment, optionally with hydrogenated the polydiene segment.