Synthesis of Ethylene/Isoprene Copolymers Containing Cyclopentane/Cyclohexane Units as Unique Elastomers by Half-Titanocene Catalysts

• DOI: 10.1021/acs.macromol.2c02399
• Publication Date: 2023-01-19T08:08:46Z
• Authors: Lijuan Guo; Ryoji Makino; Daisuke Shimoyama; Joji Kadota; Hiroshi Hirano; Kotohiro Nomura
• Keywords: Cyclopentanes; Isoprene; Elongation; Thermoplastic elastomer

Ethylene (E) copolymers with isoprene (IP) possessing higher glass-transition temperatures (Tg values, −7.1 to 29.2 °C) than those prepared by the reported catalysts below −18 have been in copolymerization using half-titanocene containing phenoxide ligand, Cp′TiCl2(O-2,6-iPr2-4-R-C6H2) [Cp′ = C5Me5 (Cp*), R H (1), SiEt3 (2)]. Their microstructural analysis NMR spectra revealed that contained cyclopentane (major) and cyclohexane units, formed cyclization after IP subsequent ethylene insertions, addition 1,4- 3,4-IP inserted units observed as major catalysts. The 1,2,4-Me3C5H2 analogue (R H) showed better incorporation, but resulting E/IP possessed rather low Tg values compared 1,2 due less unit microstructure. value copolymer increased upon increase of content, degree was dependent catalyst employed. Due their unique microstructure, 1,2–MAO systems exhibit promising tensile elastic properties. strength initially decreased an content along elongation at break (up 600%, 3.3–15.6 mol %) then gradually further contents (IP 18.1–21.5 %); preserving observation yield stress.