Polyurethane-b-poly(N-isopropyl acryl amide) block copolymers having 0-40% N-isopropyl acryl amide have been synthesized via AB crosslinked polymerization technique and tested for various properties. It was possible to systematically control the thermal, mechanical, dynamic mechanical properties as well as swelling-deswelling characteristics of the copolymers by controlling the block length. (c) 2005 Published by Elsevier B.V.