Self-assembly and aggregation of ATRP prepared amphiphilic BAB tri-block copolymers contained nonionic ethylene glycol and fluorescent 9,10-di(1-naphthalenyl)-2-vinyl-anthracene/1-vinyl-pyrene segments

Abstract Two novel amphiphilic BAB -type block copolymers, ADN-PEG3400-ADN and Py-PEG3400-Py containing deep blue and bluish-green fluorescent moieties were prepared using atom transfer radical polymerization (ATRP) (where, ADN  = poly(9,10-di(1-naphthalenyl)-2-vinylanthracene), Py  = poly(1-vinyl pyrene) and PEG3400  = poly(ethylene glycol) with M n  = 3400 g/mol). The GPC number averaged molecular weights (MW) of the block copolymers were M n  = 9600 and 13,800 g/mol, respectively, based on polystyrene MW standards. The PEG3400 segment has a melting temperature ( T m peak) at 64–65 °C, whereas the glass transition temperatures ( T g midpoint) of the ADN and Py segments were found to be 230 °C and 193 °C, respectively, and are similar to their respective homopolymers indicating complete microphase segregration. The photoluminescence (PL) emission of the copolymers ADN-PEG3400-ADN exhibited two maxima at 423.5 nm and 441.5 nm while Py-PEG3400-Py has a maximum at 488.5 nm. Both copolymers form individual spherical micelles with diameter from 30 to 90 nm for Py-PEG3400-Py and 40–160 nm for ADN-PEG3400-ADN . The micelles, however, transform into cross-linked pearl-necklace-like aggregates at polymer concentrations above 1000 ppm, which may be attributed to the physical cross-linking between adjacent spherical micelles caused by the PEG3400 segments.