Poly(oxy-1,4-butanediyl), α-[[[4(or 6)-methyl-3-[[[[(1-methylpropylidene)amino]oxy]carbonyl]amino]phenyl]amino]carbonyl]-ω-[[[[4(or 6)-methyl-3-[[[[(1-methylpropylidene)amino]oxy]carbonyl]amino]phenyl]amino]carbonyl]oxy]-