Pixin Wang, I. Ando
Jun 8, 1998
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0
Influential Citations
6
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract High-resolution 13 C CP/MAS NMR and pulse 1 H NMR experiments were carried out for hydrated poly(aspartic acid) sodium salt, in order to investigate the conformation and molecular motion of the polymer. From these experimental results, it is found that the main-chain conformation of poly(aspartic acid) sodium salt which takes an α-helix form in the dry state is not drastically affected by an addition of water. In the 13 C CP/MAS NMR spectrum, a new peak at ca. 184 ppm appears, which comes from the formation of hydrogen bond between the carbonyl carbon of the side chains and water, and the intensity of the peak is associated with the water content. The 13 C spin-lattice relaxation time ( T 1 ) experiments show that the T 1 values for the individual carbons of the polymer are decreased with an increase in the water content. This shows that the mobility of the polymer is increased with an increase in the water content. Further, the 1 H spin-spin relaxation time ( T 2 ) experiments show that the polymer has the two or three components with different molecular motion. With an increase in the water content or temperature, the T 2 values of hydrated PAANa are increased. This shows that the molecular motion is increased. In the high water content, the polymer has a signal component in the molecular motion. This shows that the polymer is uniformly hydrated.