2-(Dimethylamino)ethyl 2-methyl-2-propenoate polymer with 2-hydroxyethyl 2-methyl-2-propenoate, methyl 2-methyl-2-propenoate, α-(2-methyl-1-oxo-2-propenyl)-ω-methoxypoly(oxy-1,2-ethanediyl) and octadecyl 2-methyl-2-propenoate