T.Ben Hadda

Bio: T.Ben Hadda is an academic researcher from University of Rennes. The author has contributed to research in topics: Ruthenium & Ligand. The author has an hindex of 1, co-authored 1 publications receiving 59 citations.

Controlled/“Living” Radical Polymerization. Kinetics of the Homogeneous Atom Transfer Radical Polymerization of Styrene

Abstract: The homogeneous atom transfer radical polymerization (ATRP) of styrene using solubilizing 4,4‘-dialkyl substituted 2,2‘-bipyridines yielded well-defined polymers with Mw/Mn ≤ 1.10. The polymerizations exhibited an increase in molecular weight in direct proportion to the ratio of the monomer consumed to the initial initiator concentration and also exhibited internal first-order kinetics with respect to monomer concentration. The optimum ratio of ligand-to-copper(I) halide for these polymerizations was found to be 2:1, which tentatively indicates that the coordination sphere of the active copper(I) center contains two bipyridine ligands. The exclusive role for this copper(I) complex in ATRP is atom transfer, since at typical concentrations that occur for these polymerizations (≈10-7−10-8 M), polymeric radicals were found not to react with the copper(I) center in any manner that enhanced or detracted from the observed control. ATRP also exhibited first-order kinetics with respect to both initiator and copper...

Polymers with Very Low Polydispersities from Atom Transfer Radical Polymerization

Abstract: A radical polymerization process that yields well-defined polymers normally obtained only through anionic polymerizations is reported. Atom transfer radical polymerizations of styrene were conducted with several solubilizing ligands for the copper(I) halides: 4,4′-di-tert-butyl, 4,4′-di-n-heptyl, and 4,4′-di-(5-nonyl)-2,2′-dipyridyl. The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities (ratio of the weight-average to number-average molecular weights of 1.04 to 1.05). Similar results were obtained for the polymerization of acrylates.

Tuning the Excited-State Properties of Platinum(II) Diimine Dithiolate Complexes

Abstract: Two series of Pt(diimine)(dithiolate) complexes have been prepared in order to investigate the effects of molecular design on the excited-state properties of this chromophore. The first series comprises Pt(dbbpy)(dithiolate) complexes where dbbpy = 4,4‘-di-tert-butyl-2,2‘-bipyridine and the dithiolates are 1-(tert-butylcarboxy)-1-cyanoethylene-2,2-dithiolate (tbcda), 1-diethylphosphonate-1-cyanoethylene-2,2-dithiolate (cpdt), 6,7-dimethyl-quinoxaline-2,3-dithiolate (dmqdt), maleonitriledithiolate (mnt), and toluene-3,4-dithiolate (tdt). The second series comprises Pt(diimine)(tdt) complexes where the diimines are 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen), 4,4‘-di-tert-butyl-2,2‘-bipyridine (dbbpy), 4,4‘-dimethyl-2,2‘-bipyridine (dmbpy), 2,2‘-bipyridine (bpy), 1,10-phenanthroline (phen), 5-chloro-1,10-phenanthroline (Cl-phen), 4,4‘-dichloro-2,2‘-bipyridine (Cl2bpy), and 4,4‘-bis(ethoxycarbonyl)-2,2‘-bipyridine (EC-bpy). All of the compounds display solvatochromic absorption bands and solution lumine...

Atom Transfer Radical Copolymerization of Styrene and n-Butyl Acrylate

Abstract: Styrene and n-butyl acrylate were copolymerized by atom transfer radical polymerization catalyzed by CuBr/4,4‘-di(5-nonyl)-2,2‘-bipyridine. Composition was consistent with a simple terminal model analysis and was independent of [CuBr]0, [I]0, and temperature for copolymerizations with initial feed content of styrene (fst)0 = 0.510. Monomer reactivity ratios evaluated from experimental data by nonlinear least-squares calculations were 0.68 ≤ r1 ≤ 0.82 and 0.22 ≤ r2 ≤ 0.26. 13C NMR spectra of styrene/n-butyl acrylate copolymers were very similar to copolymers prepared through conventional radical polymerizations, indicating that carbon-centered free radicals were generated under these conditions. Conversion/molecular weight plots showed no evidence of transfer, though measured molecular weights were consistently higher than theoretical ones. Semilogarithmic plots of monomer conversion versus time were nonlinear, indicating an irreversible termination reaction whose contribution decreases with decreasing tem...