In this thesis photo-responsive epoxy based resins were prepared by exploiting the versatile chemistry of ortho nitrobenzyl ester (o-NBE) groups which undergo spatially controlled bond formation and bond cleavage in response to UV irradiation. In a first approach, a bi functional epoxy monomer with o-NBE links was photocured by a cationically induced ring opening reaction. Photoinitiation was carried out by direct photolysis of N hydroxynaphthalimide triflate upon deep UV exposure. The crosslinking and cleavage kinetics of the photocleavable epoxy based networks were determined by FT-IR spectroscopy. Along with FT-IR experiments, the cleavage of the ether network was confirmed by sol-gel analysis revealing a decrease of the gel fraction upon prolonged UV exposure. The decrease in gel fraction correlated well with the decrease in glass transition temperature evidencing the controlled network degradation. The formation of soluble species was then used for the preparation of positive tone photo resists. Patterns with a resolution of 4 µm were produced by photolithographic processes. However, if the exposure dose exceeded 20 J/cm2 a regeneration of covalent links was observed leading to an increase in gel fraction. This UV induced formation of covalent links was used in a second approach for the design of photocurable epoxy based polymers. Polyether with pendant ortho-nitrobenzyl alcohol groups were prepared by thermally curing the photolabile bi-functional epoxy monomer in the presence of an anhydride hardener and a photobase generator. The ester of the o-NBE binding motif was hydrolyzed by the photobase generator yielding non crosslinked functional polymers which were examined by size exclusion chromatography. The polymers were then photochemically crosslinked across the o-NB alcohol groups which were forming azo compounds as photo dimerization product at high exposure doses. The photo-induced formation of polymer networks was confirmed by an increase in gel fraction and an increase of glass transition temperature. Negative toned polymer patterns were prepared which comprised of a good resolution.