Polymers of higher olefin, obtained by Ziegler-type polymerization, have been used in some critical fields, e.g., as the membrane for extracorporeal membrane oxygenation (ECMO), which plays an important role in the treatment of patients with severe COVID-19. The polymer obtained by a single-site catalyst, e.g., metallocene catalysts, demonstrated a higher performance. The homo- and co-polymerization of allyltrimethylisilane (ATMS) and 4-methyl-1-pentene (4M1P) were conducted using syndiospecific (cat 1) and isospecific (cat 2) metallocene catalysts. Cat 1 showed low conversions and provided a polymer with a higher molecular weight, while cat 2 behaved oppositely. 13C-NMR spectra certified the stereotacticity of the resultant polymer, and the resonance of the carbon atom of CH2 (αα’) between the two tertiary carbon atoms of the ATMS and 4M1P units were observed. This could be the evidence of the formation of a true copolymer. The crystallization of the polymer was explored using a differential scanning calorimeter (DSC) and wide angle X-ray diffraction (WAXD). All homopolymers and some of the copolymers showed high melting temperatures and low melting enthalpies. The WAXD patterns of the syndiotactic polymer and isotactic homopolymer or the ATMS-rich copolymer were consistent with the reported literature, but the isotactic 4M1P-rich copolymer provided the crystal form I, which is unusual for a 4M1P polymer without any pretreatment.
Both cyclic olefin copolymer (COC) and functionalized polyolefins are high-performance polyolefin materials with different outstanding properties. The introduction of functional groups into COC has the potential to yield materials that combine the advantages of both. In this work, ethylene copolymers with norbornene (NBE) or 5-norbornene-2-methanol (NBMO) are synthesized by using a metallocene catalyst. The activity and the molecular weight of copolymer of the former is much higher than that of the latter. A joint deactivation-chain transfer mechanism is proposed to interpret these observations. Chain transfer is further discussed. Through regression analysis, it is considered that the chain transfer mode of the two comonomers is the same. Three methods for the calculation of NBMO incorporation are proposed and compared, and a more suitable method is obtained, on the basis of the resonance assignment. The comparison of the copolymerization of ethylene with NBE and NBMO may indicate that NBMO has a higher coordination probability but a slower insertion rate compared to NBE.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.