title: Domain sizes in heterogeneous polymers by spin diffusion using single-quantum and double-quantum dipolar filters.
abstract: 1H spin-diffusion experiments employing a double-quantum (DQ) dipolar filter were performed for the characterization of the microdomain structure of heterogeneous samples. For this purpose the NMR spin-diffusion process was analysed based on a model morphology of three different domains with arbitrary sizes, diffusivities, and filter efficiency. General analytical solutions for z magnetization source and sink were obtained valid for a one-dimensional lamellar morphology in the full range of spin-diffusion times. These solutions of the spin-diffusion equations were used for determining the crystalline, interface, and amorphous domain sizes in polystyrene-poly(ethylene oxide) (PS-PEO) and poly(hydroxyethylmethacrylate)-poly(ethylene oxide) (PHEMA-PEO). The DQ dipolar filter has a good efficiency for PS-PEO but is only partially efficient in filtering the signal of the mobile domains in the PHEMA-PEO diblock copolymer. The domain sizes measured by the DQ filter method are compared to those obtained using the traditional dipolar filter creating z magnetization in the mobile domains.
authors.affiliation: Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Buda
authors.forename: D E
authors.initials: DE
authors.lastname: Demco
authors.forename: M
authors.initials: M
authors.lastname: Bertmer
authors.forename: B
authors.initials: B
authors.lastname: Blümich
authors.forename: B
authors.initials: B
authors.lastname: Reining
authors.forename: H
authors.initials: H
authors.lastname: Keul
authors.forename: H
authors.initials: H
authors.lastname: Höcker