The cationic polymerization of 1,3-pentadiene isomers initiated by AlCl3 was investigated in nonpolar solvent. It was shown that the polymerization was very sensitive to the initial monomer composition (proportion between the cis and trans isomers). The cis isomer favors the cross-linking reactions and double bond isomerization, whereas the trans isomer induces more cyclization. However, the behavior of the mixture of the two isomers cannot be simply deduced from a linear combination of the behavior of each isomer independently considered. Some polymerizations were realized in different alkanes (pentane, hexane, heptane, and decane). Despite similar polarity, it was observed that the higher the solvent molecular weight, the lower the total polymerization yield. These results were assigned to a different solubility of the Lewis acid and of polymer chains in the different solvents investigated. Finally, two origins of the cross-linked polymer were identified: the heterogeneity of the polymerization medium and intermolecular reactions of the active species with the polymer.

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Summary: A kinetic study of the polymerization of a mixture of 1,3‐pentadiene isomers initiated by AlCl3 was carried out in pentane at −10 and 20 °C. A second apparent monomer order was found mainly at room temperature and was explained by a complexation of propagating active centers by the polymer, the true monomer order being first. This apparent order did not result from the presence of the two isomers in the monomer mixture. Kinetic simulations confirmed this interpretation and pointed out the fact that the interaction between the polymer and the active centers was stronger at −10 °C, thus limiting the polymer conversion at this temperature. The novelty of these findings lies in the fact that the inactive complexed centers can be activated by reaction with the monomer, providing active species when necessary. The existence of active centers even after a long reaction time at room temperature, and the reactivation of the complexed centers, was evidenced by incremental monomer addition and by the formation of sulfonium ions after quenching the polymerization by an excess of dimethyl sulfide. The latter were characterized by 1H NMR spectroscopy.

Summary: The cationic polymerization of 1,3‐pentadiene initiated by AlCl3 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 (NPh3). 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 NPh3 molecule per macromolecule while the NPh3 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 NPh3 also succeeded at −10 °C. Whereas at −10 °C a dialkylation of NPh3 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 NPh3. 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 NPh3 with increasing reaction times (r = [NPh3]/[AlCl3] = 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; [AlCl3] = 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 NPh3 with increasing reaction times (r = [NPh3]/[AlCl3] = 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; [AlCl3] = 2.3 × 10−2 mol · L−1, [1,3‐pentadiene] = 1.6 mol · L−1, pentane.