Encapsulation of functional moieties within branched star polymers: Effectof chain length and solvent on site isolation

Porphyrin and pyrene photoactive cores have been encapsulated within an iso lating polymeric shell using an efficient and general strategy based on the use of dendritic initiators for the ring-opening polymerization of epsilon -caprolactone to yield functional core star polymers. The isolation of the core functionalities has been studied using fluorescence quenching and flu orescence resonance energy transfer (FRET) techniques as well as solvatochr omic probes. With increasing chain length as well as solvent polarity, enha nced site isolation of the core has been observed. These findings have been correlated to actual molecular dimensions independently measured by pulsed field gradient spin-echo (PGSE) NMR. The developed synthetic methodology o ffers a rapid route to efficient encapsulation of functional moieties and t herefore has potential for the design of new materials.