Polymerization of 1,3-Pentadiene Initiated by Aluminium Trichloride in Nonpolar Solvent: Pseudo-Control is Explained by Continuous Grafting

✍ Scribed by Marilyn Delfour; Véronique Bennevault-Celton; Hung Anh Nguyen; Hervé Cheradame; Anne Macedo

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 253 KB
• Volume: 205
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200400267

✦ Synopsis

Abstract

Summary: The cationic polymerization of 1,3‐pentadiene initiated by AlCl~3~ was studied in nonpolar solvent. It was previously shown that at room temperature the active species were long‐lived and that the number‐average molar mass of the polymer chains was increasing with the polymerization yield. In order to explain this apparent control, the macromolecules were labeled with a transfer agent, triphenylamine (NPh~3~). The latter binds to active species by electrophilic aromatic substitution. The labeling of the polymer chains indicated that at 20 °C the polymer chains mainly contained one NPh~3~ molecule per macromolecule while the NPh~3~ content was higher for the high molar mass chains due to a “grafting from” polymer transfer mechanism. Thus, the pseudo‐control was assigned to the branching reactions. The labeling process by NPh~3~ also succeeded at −10 °C. Whereas at −10 °C a dialkylation of NPh~3~ was observed, a trialkylation at 20 °C was obtained. The analysis of the polymer microstructure at both temperatures highlighted an interaction between the active centers and NPh~3~. This paper also describes a process to synthesize tri‐arm stars polymers by cationic polymerization.

RI SEC chromatograms of soluble polymers synthesized at 20 °C in the presence of NPh~3~ with increasing reaction times (r = [NPh~3~]/[AlCl~3~] = 1); (a) t = 0.25 h, (b) t = 0.5 h, (c) t = 1 h, (d) t = 2 h, (e) t = 18 h, (f) t = 48 h; [AlCl~3~] = 2.3 × 10^−2^ mol · L^−1^, [1,3‐pentadiene] = 1.6 mol · L^−1^, pentane.

magnified imageRI SEC chromatograms of soluble polymers synthesized at 20 °C in the presence of NPh~3~ with increasing reaction times (r = [NPh~3~]/[AlCl~3~] = 1); (a) t = 0.25 h, (b) t = 0.5 h, (c) t = 1 h, (d) t = 2 h, (e) t = 18 h, (f) t = 48 h; [AlCl~3~] = 2.3 × 10^−2^ mol · L^−1^, [1,3‐pentadiene] = 1.6 mol · L^−1^, pentane.