2d Nmr Studies of Synthetic Polymers

Solution and solid state two dimensional NMR are important tools for materials characterization, and for understanding the structure and dynamics of polymers. The power of NMR as a tool arises from its ability to visualize individual sites along the polymer main chain and side chain, making it possible to relate the structure and dynamics at the molecular level to the bulk macroscopic properties. The goal of many polymer NMR studies is to understand polymer structure-function relationships, as polymers with well defined properties are used extensively in the packaging and electronics industries. The thermal, mechanical, optical, or electrical properties are known to depend on the details of the polymer structure, including the stereochemistry in the polymer main chain and side chains, geometric isomerism, the presence of branches and cross links, and the chain conformation, all of which can be characterized by NMR. Polymer blends and semicrystalline polymers are also materials of great interest, and NMR plays an important role in measuring the phase structure of these materials. The NMR analysis of polymers has been historically limited by poor spectral resolution due to the repeating structure of the monomers in polymers. Resonances from defects or other microstructures are frequently not resolved from the primary polymer signals, and are difficult to detect and analyze by ID NMR. These structures can frequently be observed as the resolution is increased on proceeding from ID to 2D (or 3D) NMR. The higher resolution makes it possible to pose more precise and detailed questions about structure-function relationships in polymers.