Self-aggregation of the pyrene labeled poly(acrylic acid) in nanoscopically crowded environments

• Behavior of pyrene labeled poly(acrylic acid)s in AOT RMs was investigated.
• Static and dynamic fluorescence were used to check the stiffness of polymers in RMs.
• Spectral properties of the polymers depend on both π-π interactions and w0.

The paper investigates the behavior of pyrene labeled poly(acrylic acid) with various graft content in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles (RMs) at various hydration degrees (w0). The work is carried out by UV–vis, steady-state and time-resolved fluorescence as well as dynamic light scattering (DLS). The report indicates new insights regarding the interactions and dynamics of the fluorescent labeled polymer in the nanoscopic aqueous host. It was found that the spectral properties of the polymer depend on the H-bonds and π-π interactions. The efficiency of pyrene excimer formation indicated the “on-off” control of the polymer chain in RMs by triggering of w0. The constriction of the polymer coil in different nanocages of RMs influenced the formation of excimers. At low w0, the pyrene labeled poly(acrylic acid) senses the micellar interface. At higher hydration degree, the grafted polymer resides in the water pool of RMs with elevated polarity similar to that in the bulk water. The study discloses the ability of the pyrene-labeled polymer to sense the crowded nano-environments.