Cationic Polymerization of β ‐Pinene Using B(C ₆ F ₅ ) ₃ as a Lewis Acid for the Synthesis of Tackifiers in Pressure Sensitive Adhesives

Abstract β ‐pinene is a well‐known bio‐based monomer that can be polymerized via cationic polymerization to give low molecular weight resins that find use commercially as tackifiers. However, the controlled synthesis of these polymers by cationic polymerization is challenging due to the reactivity of commonly used Lewis acid catalysts and the propagating carbocationic species with water. Here, the cationic polymerization of β ‐pinene under mild conditions using the water stable Lewis acid tris(pentafluorophenyl)borane is demonstrated. It is shown that when combined with a suitable alcohol initiator the molecular weight of the polymer can be tuned while the kinetics are largely controlled by the concentration of tris(pentafluorophenyl)borane. The final poly( β ‐pinene) is shown to perform well as a tackifier in the formation of pressure sensitive adhesives based on polystyrene‐ b ‐polyisoprene‐ b ‐polystyrene triblock copolymers.