Novel polymer and cured product of the same

A polymer which is prepared by addition polymerizing at least one ethylenically unsaturated monomer in the presence of:

• (A) an organic polymer having a reactive silicone group of the formula:
• ##STR29## wherein R.sup.4 is a C.sub.1 -C.sub.20 alkyl group, a C.sub.6 -C.sub.20 aryl, a C.sub.7 -C.sub.20 aralkyl group or a triorganosiloxane group of the formula:
• (R").sub.3 SiO--
• in which R" is, the same or different, a C.sub.1 -C.sub.20 hydrocarbon group, X is a hydroxyl group or, the same or different, a hydrolyzable group, a is an integer of 0 to 3, b is 0, 1 or 2 and m is an integer of 1 to 18 and a polymerizable ethylenically unsaturated group in a molecule, the total number of the reactive silicone group and the unsaturated group in a molecule being on the average not less than 1.1 and the number of the ethylenically unsaturated group being on the average not less than 0.1 and said polymer being selected from the group consisting of a polyalkyleneoxide, a polyester and a ether-ester block copolymer, and
• (B) at least one component selected from the group of consisting of a radical polymerization initiator having a reactive silicone group (I), a chain transfer agent having a reactive silicone group (I) and a mixture thereof.