Modification of a hydrophilic polyurethane by crosslinking with a polydimethylsiloxane. Influence of the crosslink density and of the hydrophobic / hydrophilic balance on the water transport properties

International audienceA hydrophilic thermoplastic polyurethane (TPU) was modified by reactive extrusion to obtain in a first step a grafted and soluble material and to finally form by a hydrolysis condensation process a weakly crosslinked network. Different isocyanates were used as grafting agents and a alpha,omega-dihydroxypoly(dimethylsiloxane) (PDMS) was used to modify the hydrophilic/hydrophobic balance of the material and the chain length between the crosslinks. The influence of the isocyanate functionality and of the PDMS content were studied on the network formation and on the thermo-mechanical and water sorption properties. The networks properties were also compared with those of a TPU/PDMS blend