Synthesis and Characterization of 4-Methyl-1-Pentene/1,5-Hexadiene Isotactic Copolymers with Enhanced Low-Temperature Mechanical Performance

• DOI: 10.1021/acs.macromol.3c02654
• Publication Date: 2024-03-25T06:03:15Z
• Authors: Fabio De Stefano; Miriam Scoti; Claudio De Rosa; Rocco Di Girolamo
• Keywords: Comonomer; Tacticity; Decalin; Pentene

Novel 4-methyl-1-pentene/1,5-hexadiene isotactic copolymers (iP4MPHD) incorporating methylene-1,3-cyclopentane (MCP) cyclic co-units with concentrations in the range 4.4–17.6 mol % have been synthesized by using dimethylpyridylamidohafnium/organoboron catalyst. The influence of MCP co-unit on crystallization behavior and mechanical properties poly(4-methyl-1-pentene) (iP4MP) homopolymer has investigated detail. iP4MPHD comonomer content up to 11 crystallize form II iP4MP from polymerization solution stable I melt, whereas sample highest concentration (17.6 %) 1,5-hexadiene (1,5-HD) is amorphous does not either melt. All crystalline samples exhibit high melting temperatures, always above 120 °C, a controlled glass transition temperature close room (28–30 °C). Incorporation units into chains produces an improvement flexibility allows tailoring deformability while retaining resistance transparency homopolymer. Interestingly, maintained at low (50 °C below temperature), suggesting cooperative role both phases deformation mechanism that enhances ductility. stress–strain curves different present unusual second maximum strains higher than yielding point. Diffraction patterns recorded during revealed this associated under stretching highly disordered mesophase never described literature.