water unstable bioadhesive compositions comprising an aqueous plasticiser , a cross - linking agent , a copolymer of a hydrophilic unsaturated water soluble firt monomer a hydrophobic unsaturated water - soluble second monomer , characterised in that they have : a water activity of from 0 . 4 to 0 . 9 ; an elastic modulus at 1 rad / s of from 700 to 15 , 000 pa ; an elastic modulus at 100 rad / s of from 20000 to 40 , 000 pa ; a viscous modulus at 1 rad / s of from 400 to 14 , 000 pa ; a viscous modulus at 100 rad / s of from 1000 to 35 , 000 pa ; wherein the viscous modulus is less than the elastic modulus in frequency range of from 1 to 100 rad / s ; amd wound dressings made from them .