We report on the synthesis of photoreactive copoly-mers with high reactivity toward UV irradiation at lambda = 365 nm. To this, first thioxanthone moieties are incorporated into polymer chains via free radical polymerization. Then, upon brief UV irradiation, the thioxanthone moieties become activated and through a (formal) C,H-insertion crosslinking (CHic), polymer networks are formed. When the photopolymer is coated onto a material containing CH groups, the network becomes simultaneously covalently attached to its surface. As the reactivity of thioxanthone photosensitizers is strongly enhanced by activator substances, tertiary amines in particular, copolymers with and without a built-in activator (2-dimethylaminoethyl) methacrylate, are generated. The efficiency and the kinetics of the formation of surface-attached networks on various substrates are studied. To demonstrate the potential of the described systems for biomedical applications, they are used to manufacture functional beads that can be used for immunoassays.