13C NMR of polyolefins with a new high temperature 10 mm cryoprobe.
Recently, a high temperature 10 mm cryoprobe was developed. This probe provides a significant sensitivity enhancement for (13)C NMR of polyolefins at a sample temperature of 120-135 degrees C, as compared to conventional probes. This greatly increases the speed of NMR studies of comonomer content, sequence distribution, stereo- and regioerrors, saturated chain end, unsaturation, and diffusion of polymers. In this contribution, we first compare the (13)C NMR sensitivity of this probe with conventional probes. Then, we demonstrate one of the advantages of this probe in its ability to perform 2D Incredible Natural Abundance Double Quantum Transfer Experiment (2D INADEQUATE) in a relatively short period of time. The 2D INADEQUATE has been rarely used for polymer studies because of its inherently very low sensitivity. It becomes even more challenging for studying infrequent polyolefin microstructures, as low probability microstructures represent a small fraction of carbons in the sample. Here, the 2D INADEQUATE experiment was used to assign the (13)C NMR peaks of 2,1-insertion regioerrors in a poly(propylene-co-1-octene) copolymer.
Zhou
Zhe
Z
The Dow Chemical Company, Freeport, TX 77541, USA. zzhou@dow.com
Kümmerle
Rainer
R
Stevens
James C
JC
Redwine
David
D
He
Yiyong
Y
Qiu
Xiaohua
X
Cong
Rongjuan
R
Klosin
Jerzy
J
Montañez
Nikki
N
Roof
Gordon
G
D002247:Carbon Isotopes / Q000032:analysis / Q000737:chemistry; D003080:Cold Temperature; D004867:Equipment Design; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D011090:Polyenes / Q000032:analysis* / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013696:Temperature; D014159:Transducers
D002247:Carbon Isotopes; D011090:Polyenes; C035051:PL 732