Nuclear magnetic resonance of liquid crystalline materials: New developments and insights.

摘要

Nuclear Magnetic Resonance (NMR) was employed to study liquid crystalline polymers. Solution and state NMR methodologies were utilized to investigate polymer alignment, dynamics and morphology in both the solid and mesophase. During the course of this work new NMR methods were developed and implemented for gaining further insight into these complex materials.; Natural abundance 13C and 1H was first successfully used to study order in solutions of lyotropic aramides while varying conditions such as temperature, concentration and molecular structure. Order parameter information was extracted through spectral simulation and with the aid of solid state chemical shift measurements. This solid state tensor information was also utilized in the study of thermotropic polyesters which were thermally aligned within the NMR magnet. From this, molecular level orientational information could be gained for a series of semiflexible polyesters. High resolution NMR methods were also employed towards these materials in an effort to extract molecular level conformational arrangements and dynamics. During the course of these studies a new NMR protocol was developed which affords accurate bond distance determinations to be implemented in a simple way as well as providing information on molecular dynamics. This methodology was utilized to extract the dynamic behavior for a series of thermotropic and lyotropic polymers at a molecular level.