Synthesis of solid thermoplastic isoprene polymers using organoaluminum compounds

Cationic polymerization of isoprene using the initiating systems consisting of organoaluminum compounds (OAC = AlEt₃, AlEt₂Cl, or AlEtCl₂) and allyl chloride (ALC) is a new efficient method for the synthesis of completely soluble solid thermoplastic isoprene polymers characterized by reduced degree of unsaturation (44–50 mol.%), high glass transition temperatures (57–60 °C), and high softening points (128–180 °C). The molecular characteristics, degree of unsaturation, and softening points of the resulting isoprene polymers can be controlled by varying the ALC: AOC ratio in the initiating systems, as well as the temperature and duration of the polymerization process. The structure of the head group of the synthesized polymer was established for the first time by 1D and 2D NMR spectroscopy. It represents the allyl fragment of the polymerization initiator (ALC) connected to the 1,4-trans-unit of polyisoprene.