Carbocationic polymerization of isoprene using cumyl initiators: progress in understanding side reactions

The cationic polymerization of isoprene using cumyl chloride/B(C6F5)3 and cumyl ether/TiCl4 systems was investigated in dichloromethane or in dichloromethane/methylcyclohexane mixtures varying the polymerization conditions. Polymerizations were performed in all cases in the presence of a large excess of a proton trap (2,6-di-tert-butyl pyridine, dtBP) compared to initiator in order to suppress any protic side reactions. As a consequence, no polymerization went to completion. Independently of the reaction conditions, trans-1,4-oligomers were exclusively obtained with mainly an olefinic terminal group. It was highlighted that an important loss of double bonds yielding saturated parts was observed, even in the absence of protons, assuming that a great amount of double bond loss generally observed in isoprene cationic polymerization could be due to intramolecular cyclization reactions. Nevertheless, under particular conditions (low temperature and/or low polarity medium), branching and cross-linking reactions were also found responsible for double bond loss.

[1]  B. Voit,et al.  A Catalyst Platform for Unique Cationic (Co)Polymerization in Aqueous Emulsion. , 2015, Angewandte Chemie.

[2]  F. Peruch,et al.  Carbocationic polymerization of isoprene initiated by dimethylallyl derivatives associated with B(C6F5)3 , 2013 .

[3]  F. Peruch,et al.  Cationic polymerization of isoprene initiated by 2-cyclohexylidene ethanol–B(C6F5)3: an insight into initiation and branching reactions , 2013 .

[4]  F. Peruch,et al.  Polyisoprene synthesized via cationic polymerization: State of the art , 2012 .

[5]  J. Puskas,et al.  Bio‐inspired cationic polymerization of isoprene and analogues: state‐of‐the‐art , 2012 .

[6]  J. Puskas,et al.  Cationation of dimethylallyl alcohols by B(C6F5)3 as models of the (Re)initiation reaction in the bio‐inspired cationic polymerization of isoprene , 2011 .

[7]  C. Absalon,et al.  Carbocationic Polymerization of Isoprene Co-initiated by B (C6f5) 3: an Alternative Route Toward Natural Rubber Polymer Analogues? , 2011 .

[8]  N. P. Boreiko,et al.  Molecular Heterogeneity of Cationic Polyisoprene , 2009 .

[9]  S. Aoshima,et al.  A renaissance in living cationic polymerization. , 2009, Chemical reviews.

[10]  V. A. Rozentsvet,et al.  Microstructure of polyisoprene produced by cationic polymerization: NMR spectroscopic study , 2009 .

[11]  N. P. Boreiko,et al.  Cationic polyisoprene: Synthesis, structure, and some properties , 2009 .

[12]  C. Wesdemiotis,et al.  Biomimetic carbocationic polymerizations III: Investigation of isoprene polymerization initiated by dimethyl allyl bromide , 2009 .

[13]  C. Wesdemiotis,et al.  Biomimetic processes. IV. Carbocationic polymerization of isoprene initiated by dimethyl allyl alcohol , 2009 .

[14]  J. Kennedy,et al.  Natural rubber biosynthesis—A living carbocationic polymerization? , 2006 .

[15]  L. Sipos,et al.  Effect of Temperature, Solvent Polarity, and Nature of Lewis Acid on the Rate Constants in the Carbocationic Polymerization of Isobutylene , 2003 .

[16]  J. Kennedy,et al.  Carbocationic Copolymerization in the Presence of Electron Pair Donors. 1. Copolymerization of Isobutylene and Isoprene with the Cumyl Acetate/boron Trichloride Initiating System , 1992 .

[17]  J. Kennedy,et al.  Carbocationic copolymerization in the presence of electron pair donors. 2. Copolymerization of isobutylene and isoprene or 2,4-dimethyl-1,3-pentadiene with titanium tetrachloride-based initiating systems yielding in situ electron pair donors , 1992 .

[18]  L. Balogh,et al.  Living carbocationic polymerization of isobutylene with BCl3 coinitiation in the presence of di-tert-butylpyridine as proton trap , 1992 .

[19]  J. Kennedy,et al.  Living carbocationic polymerization. XIV: Living polymerization of isobutylene with ester•TiCl4 complexes , 1988 .

[20]  J. Kennedy,et al.  Living carbocationic polymerisation. XI. Copolymerisation of isobutylene with isoprene. Initial investigations , 1987 .

[21]  J. Kennedy,et al.  Quasiliving Carbocationic Polymerization. XV. Forced Ideal Copolymerization of Isobutylene-lsoprene , 1984 .