Monomer Sequence Distributions in Propylene−1-Butene Random Copolymers

Abstract

A new carbon-13 NMR method is presented for the quantitative determination of monomer sequence distributions and average sequence lengths in propylene-1-butene copolymers. Complete carbon-13 NMR chemical shift assignment was finalized: the peaks corresponding to comonomeric sequence distributions are assigned in terms of previous assignments, and other peaks are formulated after observation of two reference systems: a propylene homopolymer and a propylene copolymer with 8.17 mol % 1-butene. Particular attention was focused on determination of the P-centered triad sequence distributions, and the monomer sequence distributions were quantitatively determined, based directly on either the isolated carbon-13 NMR peaks or on the sequence distribution relationship equations. In addition, the effect of the propylene sequence configuration on the quantitative determination of the monomer sequence distributions of PP-centered tetrads was minimized. Molecular microstructural information was extracted with the highest possible accuracy. This method is reliable for analysis of the monomer sequence distributions in propylene-1-butene random copolymer.

Polymer chain conformation of copolymers with different monomer size: 13C NMR spectroscopy and MALS study

“…All the copolymers were analyzed according to the assignment of chemical shift previously reported: ethylene/propylene and ethylene/1-hexene according to Randall [16] and Kakugo [17], propylene/1-butene according to Zhang [18][19][20] and ethylene/4-methyl-1-pentene according to Losio et al [14].…”

Copolymerization of propylene with 1‐octene catalyzed by MgCl2/TiCl4/diether catalyst

“…MgCl 2 ‐supported TiCl 4 (MgCl 2 /TiCl 4 ) catalysts have been the most important catalyst system used in the polyolefin industry for the past two decades and now still constitute the majority of process and product innovations 19. A number of studies have reported copolymers of propylene with ethylene and 1‐butene prepared using MgCl 2 /TiCl 4 catalyst with diester as an internal donor (MgCl 2 /TiCl 4 /diester) 20–25. However, copolymerization of propylene and higher α‐olefins using MgCl 2 /TiCl 4 /diester is limited due to the low incorporation of comonomer and low polymerization activity 26–28.…”