title: A new decoupling method for accurate quantification of polyethylene copolymer composition and triad sequence distribution with 13C NMR.
abstract: (13)C NMR is a powerful analytical tool for characterizing polyethylene copolymer composition and sequence distribution. Accurate characterization of the composition and sequence distribution is critical for researchers in industry and academia. Some common composite pulse decoupling (CPD) sequences used in polyethylene copolymer (13)C NMR can lead to artifacts such as modulations of the decoupled (13)C NMR signals (decoupling sidebands) resulting in systematic errors in quantitative analysis. A new CPD method was developed, which suppresses decoupling sidebands below the limit of detection (less than 1:40,000 compared to the intensity of the decoupled signal). This new CPD sequence consists of an improved Waltz-16 CPD, implemented as a bilevel method. Compared with other conventional CPD programs this new decoupling method produced the cleanest (13)C NMR spectra for polyethylene copolymer composition and triad sequence distribution analyses.
authors.affiliation: The Dow Chemical Company, 2301 N. Brazosport Blvd., Freeport, TX 77541, USA. zzhou@dow.com
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhou
authors.forename: Rainer
authors.initials: R
authors.lastname: Kümmerle
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Qiu
authors.forename: David
authors.initials: D
authors.lastname: Redwine
authors.forename: Rongjuan
authors.initials: R
authors.lastname: Cong
authors.forename: Angela
authors.initials: A
authors.lastname: Taha
authors.forename: Dan
authors.initials: D
authors.lastname: Baugh
authors.forename: Bill
authors.initials: B
authors.lastname: Winniford