Abstract: This invention relates to the preparation of solvent soluble polymeric materials which become insoluble in solvents after exposure to actinic light, x-rays or electron beams.The polymers are linear block copolymers comprising two segments; a soft segment which forms a continuous phase, and a rigid, crystallizable photoreactive segment which forms a dispersed phase. The rigid segments are chosen from polyurethanes, polyesters, polyamides, and polyureas which contain a diacetylene group in their repeat units. The soft segments are low molecular weight rubbery polymers selected from groups such as polyethers, polyesters, polydienes, and polysiloxanes.The polymers produced are useful in a wide variety of applications in the field of coatings and graphic arts. More particularly, this invention relates to negative photoresists which are remarkable by their (1) high photosensitivity (2) great latitude in tailoring of film properties, (3) high thermal stability and (4) oxygen insensitivity.