A composition comprising (a) a compound of formula or wherein G 1, G 2, G 3 and G 4 are each independently of the other C 1 -C 4 alkyl, or G 1 and G 2 together or G 3 and G 4 together are pentamethylene; G 1 ', G 2 ', G 3 ' and G 4 ' are each independently of the other C 1 -C 4 alkyl, or G 1 ' and G 2 ' together or G 3 ' and G 4 ' together are pentamethylene; G 5, G 6, G 5 ' and G 6 ' are each independently of the other hydrogen or C 1 -C 4 alkyl; and X and X' are independently of each other hydrogen, C 1 -C 18 alkyl, C 2 -C 18 alkenyl, -O-C 1 -C 18 alkyl, -NH-C 1 -C 18 alkyl, -N(C 1 -C 6 alkyl) 2, phenyl, phenoxy or -NH-phenyl, m is 1 or 2, and when m is 1, R 1 is C 2 -C 8 alkylene or C 2 -C 8 hydroxyalkylene or C 4 -C 36 acyloxyalkylene, or, when m is 2, R 1 is (-CH 2) 2 C(CH 2 -) 2, and R 1 ' is hydrogen, C 1 -C 8 alkyl, C 1 -C 8 hydroxyalkyl or a group of formula -(C=O)-C 1 -C 40 alkyl, or -O-R 1 ' together with the -CH- group linking them are the group -(C=O)-, (b) a compound of formula wherein A is based on an organic isocyanate, wherein the radical(s) -S-R are introduced by reaction with isocyanate groups, R is C 2 -C 40 alkyl which is optionally substituted and/or interrupted, and n is equal to or greater than 1, and (c) a polymeric substrate. (a) a compound of formula or wherein G 1, G 2, G 3 and G 4 are each independently of the other C 1 -C 4 alkyl, or G 1 and G 2 together or G 3 and G 4 together are pentamethylene; G 1 ', G 2 ', G 3 ' and G 4 ' are each independently of the other C 1 -C 4 alkyl, or G 1 ' and G 2 ' together or G 3 ' and G 4 ' together are pentamethylene; G 5, G 6, G 5 ' and G 6 ' are each independently of the other hydrogen or C 1 -C 4 alkyl; and X and X' are independently of each other hydrogen, C 1 -C 18 alkyl, C 2 -C 18 alkenyl, -O-C 1 -C 18 alkyl, -NH-C 1 -C 18 alkyl, -N(C 1 -C 6 alkyl) 2, phenyl, phenoxy or -NH-phenyl, m is 1 or 2, and when m is 1, R 1 is C 2 -C 8 alkylene or C 2 -C 8 hydroxyalkylene or C 4 -C 36 acyloxyalkylene, or, when m is 2, R 1 is (-CH 2) 2 C(CH 2 -) 2, and R 1 ' is hydrogen, C 1 -C 8 alkyl, C 1 -C 8 hydroxyalkyl or a group of formula -(C=O)-C 1 -C 40 alkyl, or -O-R 1 ' together with the -CH- group linking them are the group -(C=O)-, G 1, G 2, G 3 and G 4 are each independently of the other C 1 -C 4 alkyl, or G 1 and G 2 together or G 3 and G 4 together are pentamethylene; G 1 ', G 2 ', G 3 ' and G 4 ' are each independently of the other C 1 -C 4 alkyl, or G 1 ' and G 2 ' together or G 3 ' and G 4 ' together are pentamethylene; G 5, G 6, G 5 ' and G 6 ' are each independently of the other hydrogen or C 1 -C 4 alkyl; and X and X' are independently of each other hydrogen, C 1 -C 18 alkyl, C 2 -C 18 alkenyl, -O-C 1 -C 18 alkyl, -NH-C 1 -C 18 alkyl, -N(C 1 -C 6 alkyl) 2, phenyl, phenoxy or -NH-phenyl, m is 1 or 2, and when m is 1, R 1 is C 2 -C 8 alkylene or C 2 -C 8 hydroxyalkylene or C 4 -C 36 acyloxyalkylene, or, when m is 2, R 1 is (-CH 2) 2 C(CH 2 -) 2, and R 1 ' is hydrogen, C 1 -C 8 alkyl, C 1 -C 8 hydroxyalkyl or a group of formula -(C=O)-C 1 -C 40 alkyl, or -O-R 1 ' together with the -CH- group linking them are the group -(C=O)-, (b) a compound of formula wherein A is based on an organic isocyanate, wherein the radical(s) -S-R are introduced by reaction with isocyanate groups, R is C 2 -C 40 alkyl which is optionally substituted and/or interrupted, and n is equal to or greater than 1, and A is based on an organic isocyanate, wherein the radical(s) -S-R are introduced by reaction with isocyanate groups, R is C 2 -C 40 alkyl which is optionally substituted and/or interrupted, and n is equal to or greater than 1, and (c) a polymeric substrate.