Multiple-quantum NMR on structure, orientation, morphology and dynamics of polymers, biomolecules and ordered tissues

• Published in: Comptes rendus. Chimie Vol. 9; no. 3-4; pp. 346 - 356
• Main Authors: BUDA, Alina Adams, DEMCO, Dan Eugen, BERTMER, Marko, BLÜMICH, Bernhard
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Paris Elsevier 01.03.2006
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Magnetic resonance techniques; mössbauer spectroscopy; Other methods of structure determination; Physics; Structure of solids and liquids; crystallography; Solid state; Soft material; Animal fiber; Lipids; Nuclear magnetic resonance; Polymers; Dipole interactions; Structural analysis
• ISSN: 1631-0748; 1878-1543
• DOI: 10.1016/j.crci.2005.06.020

A survey of recent homo- (1H) and heteronuclear (13C-1H) multiple-quantum (MQ) NMR experiments performed in our group at RWTH-Aachen on soft solids is given. MQ build-up curves are used for measurement of residual van Vleck moments and as dipolar filters in spin-diffusion experiments. The orientation studies were made with the help of MQ edited spectra that show Pake doublets. Proton homonuclear as well as 13C-1H heteronuclear residual dipolar couplings were measured site-selectively and for the overall polymer chains and correlated with the cross-link density and network deformation in elastomers and thermoplastic elastomers. The heterogeneity of the segmental dynamics of poly(dimethylsiloxane) chains grafted onto hydrophilic silica was studied by bimodal double- (DQ) and triple-quantum (TQ) build-up curves. The complex morphology of Nylon-6 fibers was characterized with the help of spin-diffusion experiments using a new dipolar filter based on the excitation of DQ coherences. The same procedure was employed for the investigation of the distribution of the residual dipolar couplings of lecithin molecules grafted on the walls of submicrone cylindrical pores. The distribution of the orientation of collagen fibrils in Achilles tendons was estimated from 1H DQ filtered spectra.