This contribution reports that synthesis of polystyrene based photoactive polymeric nanoparticles by radical copolymerization and Menschutkin Chemistry methodology. In the first step, poly(styrene-co-chloromethyl styrene) was achieved by thermally initiated radical copolymerizations and subsequently copolymers were reacted to commercially available Type II photoiniator (Michler's ketone) in dilute condition in order to achieve intramolecular crosslinked polymeric nanoparticles. After the characterization studies, polymeric nanoparticles were used for free radical photopolymerization of methacrylic formulations to determine the initiation efficiency. Upon UV irradiation, resulting polymeric nanoparticle lost its globular structure by releasing benzophenone part and transformed into linear copolymer analogue. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1998-2003