Exfoliation of zinc-layered hydroxide by luminescent conjugate polyelectrolyte: synthesis and photophysical aspects

Exfoliation of layered materials is of significant interest for both the fundamental scientific studies and technological applications. In this work, the π-conjugated polymer, poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene] potassium (MSP-PPV), was intercalated/exfoliated between the lamellae of the zinc-layered hydroxide (ZHL) to produce luminescent hybrid materials. This process is highly attractive because the intercalation/exfoliation of the MSP-PPV polymer in the sheets of zinc-layered hydroxide was realized by anionic exchange at room temperature. Depending on the amount of polyelectrolyte used in the preparation of the hybrid compounds (MPS-PPV/ZHL), the intercalation reaction was followed by exfoliation of the zinc-layered hydroxide layers. At higher MSP-PPV concentration used in the experiment, the resulting material presented a high degree of exfoliation of the zinc-layered hydroxide sheets, as suggested by both the X-ray diffraction and scanning electron microscopic images. Elemental analysis, nuclear magnetic resonance and Fourier transform infrared spectroscopy also confirmed the interaction between MSP-PPV anionic polyelectrolyte and the sheets of zinc-layered hydroxide matrix. In addition, in order to better understand the photoluminescent behavior, a complete characterization of optical properties of the MSP-PPV/ZHL hybrids was also performed. Due to the MPS-PPV presence, all hybrid materials showed absorption bands in the visible region (≈450 m) with emission band in the green region (≈560 m). Moreover, the photophysical properties of the MSP-PPV intercalated/exfoliated can be easily tuned by changing their concentration demonstrating that the zinc-layered hydroxide material plays an important role in preventing the aggregation and photostability of the anionic polyelectrolyte. Graphical Abstract