Tailor-Made Fluorinated Copolymer/Clay Nanocomposite by Cationic RAFT Assisted Pickering Miniemulsion Polymerization

Fluorinated polymers in emulsion find enormous applications in hydrophobic surface coating. Currently, lots of efforts are being made to develop specialty polymer emulsions which are free from surfactants. This investigation reports the preparation of a fluorinated copolymer via Pickering miniemulsion polymerization. In this case, 2,2,3,3,3-pentafluoropropyl acrylate (PFPA), methyl methacrylate (MMA), and <i>n</i>-butyl acrylate (nBA) were copolymerized in miniemulsion using Laponite-RDS as the stabilizer. The copolymerization was carried out via reversible addition–fragmentation chain transfer (RAFT) process. Here, a cationic RAFT agent, <i>S</i>-1-dodecyl-<i>S</i>′-(methylbenzyltriethylammonium bromide) trithiocarbonate (DMTTC), was used to promote polymer-Laponite interaction by means of ionic attraction. The polymerization was much faster when Laponite content was 30 wt % or above with 1.2 wt % RAFT agent. The stability of the miniemulsion in terms of zeta potential was found to be dependent on the amount of both Laponite and RAFT agent. The miniemulsion had particle sizes in the range of 200–300 nm. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) analyses showed the formation of Laponite armored spherical copolymer particles. The fluorinated copolymer films had improved surface properties because of polymer–Laponite interaction

Recognition of Hg²⁺ and Cr³⁺ in Physiological Conditions by a Rhodamine Derivative and Its Application as a Reagent for Cell-Imaging Studies

A new rhodamine-based receptor, derivatized with an additional fluorophore (quinoline), was synthesized for selective recognition of Hg²⁺ and Cr³⁺ in an acetonitrile/HEPES buffer medium of pH 7.3. This reagent could be used as a dual probe and allowed detection of these two ions by monitoring changes in absorption and the fluorescence spectral pattern. In both instances, the extent of the changes was significant enough to allow visual detection. More importantly, the receptor molecule could be used as an imaging reagent for detection of Hg²⁺ and Cr³⁺ uptake in live human cancer cells (MCF7) using laser confocal microscopic studies. Unlike Hg­(ClO₄)₂ or Hg­(NO₃)₂ salts, HgCl₂ or HgI₂ failed to induce any visually detectable change in color or fluorescence upon interaction with <b>L</b>_<b>1</b> under identical experimental conditions. Presumably, the higher covalent nature of Hg^II in HgCl₂ or HgI₂ accounts for its lower acidity and its inability to open up the spirolactam ring of the reagent <b>L</b>_<b>1</b>. The issue has been addressed on the basis of the single-crystal X-ray structures of <b>L</b>_<b>1</b>·HgX₂ (X^– = Cl^– or I^–) and results from other spectral studies

Recognition of Hg²⁺ and Cr³⁺ in Physiological Conditions by a Rhodamine Derivative and Its Application as a Reagent for Cell-Imaging Studies

A new rhodamine-based receptor, derivatized with an additional fluorophore (quinoline), was synthesized for selective recognition of Hg²⁺ and Cr³⁺ in an acetonitrile/HEPES buffer medium of pH 7.3. This reagent could be used as a dual probe and allowed detection of these two ions by monitoring changes in absorption and the fluorescence spectral pattern. In both instances, the extent of the changes was significant enough to allow visual detection. More importantly, the receptor molecule could be used as an imaging reagent for detection of Hg²⁺ and Cr³⁺ uptake in live human cancer cells (MCF7) using laser confocal microscopic studies. Unlike Hg­(ClO₄)₂ or Hg­(NO₃)₂ salts, HgCl₂ or HgI₂ failed to induce any visually detectable change in color or fluorescence upon interaction with <b>L</b>_<b>1</b> under identical experimental conditions. Presumably, the higher covalent nature of Hg^II in HgCl₂ or HgI₂ accounts for its lower acidity and its inability to open up the spirolactam ring of the reagent <b>L</b>_<b>1</b>. The issue has been addressed on the basis of the single-crystal X-ray structures of <b>L</b>_<b>1</b>·HgX₂ (X^– = Cl^– or I^–) and results from other spectral studies