Optimum measurement temperature for elucidating incomplete phase separation in core-shell latexes by solid state NMR
✍ Scribed by Katharina Landfester; Hans-Wolfgang Spiess
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 486 KB
- Volume
- 17
- Category
- Article
- ISSN
- 1022-1336
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✦ Synopsis
Abstract
Core‐shell latexes with a core of poly(buty1 acrylate) (PBuA) and a shell of poly(methyl methacrylate) were studied by solid‐state nuclear magnetic resonance (NMR) methods at different temperatures. ^13^C cross polarization/magic angle spinning spectra show differences in mobility in the mobile PBuA phase. In spin‐diffusion experiments the sensitivity of the NMR parameters towards the interphase structure and towards the entire core‐shell structure changes with varying temperature. For an efficient characterization of interphase structures in core‐shell systems the measuring temperature has to be optimized, i.e. the mobility gradient between the two phases within the particle must be sufficiently high to allow for effective selection by the dipolar filter. Yet, the spin diffusion coefficient of the mobile component should be high enough to allow quantitative evaluation of length scales. It is shown that a measuring temperature of about 60–70 K above the glass transition temperature of the mobile component represents an optimum for fulfilling the different requirements simultaneously.