Characterization of Sn-Containing Polymer Chain Ends of Polybutadiene Using ¹H/¹³C/¹¹⁹Sn Triple-Resonance 3D-NMR

Abstract

1 H/ 13 C/ 119 Sn triple-resonance 3D-NMR spectroscopy is used to characterize the tin-containing structures in the organotin polymer n-Bu3SnPBD (PBD ) polybutadiene). Triple-resonance techniques, when used together with pulsed field gradient coherence selection, permit selective detection of the structure fragments near 119 Sn atom while removing intense signals of the PBD backbone from the spectrum. Three frequency dimensions provide enormous spectral dispersion, permitting the resolution of many signals that are not observable in 1D-NMR spectra. The simultaneous correlation of resonances from three nuclei provides a large amount of unambiguous atomic connectivity information. The capabilities of modern instruments are such that it is possible to perform these experiments without the benefit of isotopic labeling, despite the low concentration of chain ends and the low occurrence of fragments with 1 H, 13 C, and 119 Sn isotopes.

Organotin Polymers

“…102 Organotin polymers were prepared by adding tri-n-butyltin chloride to polybutadiene with lithium living chain ends. 103 Triple resonance 1 H/ 13 C/ 119 Sn threedimensional (3D) methods were used to show the relative abundances of precise organotin end group structures and to compare these results with the internal additions. For instance, it was found that the number of vinyl-1,2-butadiene units, 26, at the chain ends is essentially the same as the percentage of these units in the main chain.…”

Molecular mobility and structure of ultrasonically treated unfilled butadiene rubber

“…The study of the molecular structure and dynamics of polymers with solid‐state NMR has been a field of substantial interest;31–33 BR has received considerable attention in a number of such investigations 29, 30, 34–39. The NMR relaxation behavior of BR has been used to investigate the crosslinking,40, 41 temperature behavior,42 molecular weight between crosslinks,43 and various attributes of tin‐containing BR 44. NMR relaxation and the pulsed‐gradient spin–echo (PGSE) NMR method45, 46 have been used to study the diffusion of BR,47–49 devulcanized SBR,50, 51 and silicone rubber 52, 53…”

Organometallic Polymers of Germanium, Tin and Lead

“…The latter process was followed either by addition of trialkyltin chlorides to end-cap the polymers with trialkyltin groups or by addition of an antioxidant to terminate the polymerization and to end-cap the polymers with methyl groups 182 . One-dimensional 119 Sn NMR and 1 H/ 13 C/ 119 Sn triple-resonance three-dimensional NMR studies of organotin-containing polybutadienes were carried out to provide information on the microstructure of the organotin-containing polymers 183,184,199 . iv.…”

“…To get a more detailed understanding of the microstructure of tin-containing polymers, 1 experiments of polybutadienes containing tributyltin groups at the chain ends were carried out 183,184 . The combination of 1D, 2D and 3D NMR experiments allowed a detailed assignment of all 1 H, 13 C and 119 Sn NMR signals of the different structures observed.…”