Author/Authors :
Bertmer، نويسنده , , Marko and Demco، نويسنده , , Dan E. and Wang، نويسنده , , Mingfei and Melian، نويسنده , , Claudiu and Marcean-Chelcea، نويسنده , , Ramona I. and Fechete، نويسنده , , Radu and Baias، نويسنده , , Maria and Blümich، نويسنده , , Bernhard، نويسنده ,
Abstract :
Segmental dynamic heterogeneity of short-chain grafted poly(dimethylsiloxane) (PDMS) on pyrogenic silica was investigated using 1H NMR spin-diffusion. A double-quantum dipolar filter was employed for selection of the interface (rigid) region. One-dimensional spin-diffusion equations were solved numerically for a space distribution of spin diffusivity D(x) of the mobile PDMS chains. The degree of heterogeneity can be quantified by the parameters of Gaussian and exponential diffusivity distribution functions which yield similar diffusivities. The rigid and mobile domain sizes and spin diffusivities were correlated with the PDMS chain length, the temperature, and 1H residual dipolar couplings.
