Switchable adhesive compositions are disclosed comprising an adhesive component, which is formed from a material or materials capable of undergoing cross-linking with isocyanale other than by free radical polymerisation and at least one isocyanate having an average of more than one isocyanate functions, unsaturated curable molecules mixed in or partially bound in with the adhesive component, or unsaturated curable moieties fully bound in to the material or materials capable of undergoing cross-linking with isocyanate, and a photoinitiator. The adhesive composition forms a tacky gel-like pressure sensitive adhesive that is capable of moulding to a substrate, and upon activation of the photoinitiator the curable molecules or moieties cross-link to form a dense 3-dimensional network through the adhesive component which causes the composition to become less tacky and to form an elastic film with reduced peel strength.
