Polarization transfer solid-state NMR for studying soft matter: From surfactants to the stratum corneum

Sammanfattning: The work presented in this thesis is dedicated to theoretical development, experimental testing and application of polarization transfer solid-state nuclear magnetic resonance (PT ssNMR). PT ssNMR is an analytical tool which provides detailed information about molecular mobility in model or simple soft matter systems at the low water content regime, enabling the creation of phase diagrams. Soft matter encompasses not only every-day-use materials, such as medical formulations and washing powders, but also a large variety of biological tissue, for example the stratum corneum (SC). It is useful to characterize molecular mobility at varying conditions, because changing temperature or water content affects macroscopic material properties, for instance permeability, flexibility and toughness. Furthermore, PT ssNMR enables recognition and qualitative description of the coexisting solid- and liquid crystalline phases. Such two-phase coexistence regions dominate the phase diagrams at low water contents, especially in systems equilibrated by contact with humid atmosphere, such as washing powder. In the investigation of complex materials, for example SC, the outer layer of the skin, PT ssNMR provides molecular insight into the mobility of different components, protein and lipid in the case of SC, thus helping to understand and explain properties of the skin barrier.