A poly(arylsulphonylurethane) of molecular weight 450-1500 of formula (II) ##STR32## wherein n is an integer and 2???n???5 and A is a di-, tri, tetra- or pentavalent organic radical, depending whether n is equal to 2, 3, 4 or 5 respectively, and A is the residue of a polyol of structure ##STR33## and A is a member selected from the group consisting of polymethylene glycols, polyoxyalkylene glycols