Synergistic enhancement of electron-accepting and-donating ability of nonconjugated polymer nanodot in micellar environment

Abstract

Understanding the fundamental electron-transfer dynamics in photoactive carbon nanoparticles (CNPs) is vitally important for their fruitful application in photovoltaics and photocatalysis. Herein, photoinduced electron transfer (PET) to and from the nonconjugated polymer nanodot (PND), a new class of luminescent CNP, has been investigated in the presence of N,N-dimethylaniline (DMA) and methyl viologen (MV2+) in homogeneous methanol and sodium dodecyl sulfate (SDS) micelles. It has been observed that both DMA and MV2+ interact with the photoexcited PND and quench the PL intensity as well as excited-state lifetime in bulk methanol. While in bulk methanol, purely diffusion-controlled PET from DMA to MV2+ via PND has been observed, the mechanism and dynamics differ significantly in SDS micelles. In contrast to homogeneous methanol medium, a distinct synergic effect has been observed in SDS micelles. The presence of both DMA and MV2+ enhances the electron-accepting and-donating abilities of PND in SDS micelles. Time-resolved photoluminescence (PL) measurements reveal that the PET process in SDS micelles is nondiffusive in nature mainly due to instantaneous electron transfer at the confined micellar surface. These results have been explained on the basis of heterogeneous microenvironments of SDS micelles which compartmentalize the donor and acceptor inside its micellar pseudo phase. The present findings provide valuable insights into the intrinsic relation between redox and PL properties of nonconjugated PND. © 2017 American Chemical Society.