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A new trithiocarbonate functionalized cis-1,4-polyisoprene was obtained from oxidative degradation of natural rubber followed by reductive amination and amidation. The structure of the resulting functionalized cis-1,4-polyisoprene was confirmed by a combination of 1H NMR spectroscopy, 13C NMR spectroscopy, MALDI-TOF mass spectrometry and FTIR spectroscopy. 1H NMR spectroscopy showed that the trithiocarbonate functionality was equal to one. The well-defined trithiocarbonyl-end functionalized cis-1,4-polyisoprene was used as a macromolecular chain transfer agent (macroCTA) to mediate the RAFT polymerization of t-BA using AIBN as the initiator ([t-BA]0/[macroCTA]0/[AIBN]0 = 250/1/0.2) in toluene at 60 °C. The resulting PI-b-P(t-BA) diblock copolymer presents an unimodal SEC trace shifted toward higher molecular weight in comparison with the SEC trace of the macroCTA, indicating that the polymerization of the second block is effective. The characteristics of the copolymer were determined by SEC ( M ¯ n = 26,000 g mol−1, PDI = 1.76) and 1H NMR spectroscopy ( DP ¯ n (PI) = 62 and DP ¯ n (P(t-BA)) = 87).

Depolymerization of 20% epoxidized cis-1,4-polybutadiene was carried out through alkenolysis of the butadiene repeat units (B) using 4-octene as depolymerizing agent (DA) and bis(tricyclohexyl phosphine)benzylidene ruthenium (IV) dichloride (1) as catalyst. The average molecular weight of the depolymerization products was determined by NMR, and SEC, and their constituents were identified by GC MS. Cis-4-octene was found more efficient in performing the depolymerization as compared to its trans isomer. Besides dodeca-4,8-diene and hexadeca-4,8,12-triene, 2,3-di[3-heptenyl]-oxirane with a cis oxirane configuration was clearly characterized. Beside the DA to B mole ratio, the catalyst to double bond mole ratio was observed as the major factor controlling the molecular weight of the depolymerization products and the 2,3-di[3-heptenyl]-oxirane yields.

Resume Un caoutchouc synthetique (CK) et deux caoutchoucs naturels liquides (CF et Cf) ont ete selectionnes en fonction de leur teneur en extremites phenylcetone (EP) et methylcetone (EM). L’oxydation acceleree est conduite par barbotage d’oxygene dans de solutions (benzene) de concentration constante en polyisoprenes (10 g l−1) et de concentration variable en phenylhydrazine (20 mmol l−1