A new method for synthesis of smart nanohydrogels under additives-free conditions and at high solid content is presented. The new core-shell nanohydrogels with cross-linked poly(N-isopropylacrylamide) (PNIPAAm) core and hydrophilic poly(glycidol) (PGI) shell were obtained by photocross-linking of PGI-b-PNIPAArn copolymers above their phase transition temperature (T-c). As UV-active group, the chromophore 2-(dimethylmaleimido)-N-ethylacrylamide (DMIAAm) was synthesized and successfully incorporated in the PNIPAAm segment, while poly(glycidol) chains were responsible for stability of aggregates above T,. Photo-cross-linkable block copolymers with different PG1 length (DP = 55 and 100), DMIAAm chromophore content, and PG1/PNIPAAm block ratio were synthesized for this investigation. It was found that the efficacy of cross-linking strongly depended on the length of PGI block in the copolymer. In the case of copolymers with shorter PGI chains formation of fully cross-linked nanohydrogels was observed already at 45 degrees C, while for copolymers with longer PGI chains monomodal nanohydrogels were formed at 55 degrees C. In contrast at given temperature, the rate of cross-linking was independent of chromophore content in copolymer and copolymer composition.