Fatty acids, C18-unsatd., dimers, diisocyanates, polymers with 2,3-bis(.gamma.-.omega.-perfluoro-C4-18-alkyl)-1,4-butanediol, 1,6-diisocyanato-2,2,4(or 2,4,4)-trimethylhexane and 2,2-(methylimino)bisethanol