Merging Styrene and Diene Structures to a Cyclic Diene: Anionic Polymerization of 1‐Vinylcyclohexene (VCH)
Christoph Hahn, Moritz Rauschenbach, Holger Frey
Abstract
Abstract We report the first anionic polymerization of 1‐vinylcyclohexene (VCH). This structure may be considered as an intermediate between dienes and styrene. The polymerization of this cyclic 1,2‐disubstituted 1,3‐diene proceeded quantitatively in cyclohexane at 25 °C with sec‐butyllithium as an initiator. The obtained polymers have well‐controlled molecular weights in the range of 5 to 142 kg mol −1 , controlled by the molar ratio of monomer and initiator, with narrow molecular weight distributions ( Đ <1.07–1.20). In situ 1 H NMR kinetic characterization revealed a weak gradient structure for the copolymers of styrene and VCH, ( r Sty =2.55, r VCH =0.39). P(VCH) obtained in cyclohexane with sec ‐BuLi as an initiator showed both 1,4‐ and 3,4‐incorporation mode (ratio: 64 : 36). It was demonstrated that the microstructure of the resulting P(VCH) can be altered by the addition of a modifier (THF), resulting in increasing 3,4‐microstructure (up to 78 %) and elevated glass‐transition temperature up to 89 °C. Thus, the monomer VCH polymerizes carbanionically like a diene, however leading to rigid polymers with high glass transition temperature, which provides interesting options for combination with other dienes to well‐defined polymer architectures and materials.