Solid-state NMR Study On The Structure Of Some Polymer Complexes

This dissertation is organized in two parts.PART I: NMR study on the conduction mechanism of poly(vinyl pyrrolidone)/LiC104 polymer electrolyteVariable temperature C CP/MAS, ⁷Li DD/MAS NMR spectroscopies combined with ¹H spin-spin relaxation time T₂ as well as ⁷Li spin-lattice relaxation time T₁ measurements have been employed to study polyvinyl pyrrolidone(PVP)/ LiClO₄ complexs, with the purpose of elucidating the conducting mechanism of the electrolytes.The following conclusions can be drawn from the study.1. The complex is highly rigid and the rigidity will decrease gradually with the increase of the content of LiClO₄.2. Polymer and LiClO₄ act as donor and acceptor in the coplex.3. There are two types of interaction between lithium ion and the carbonyl of the polymer. The first one is: one lithium ion tightly interacts with one carbonyl; The second one is that one lithium ion loosely complex with several carbonyls. The second type of interaction is dominant when the (Li:O) ratio is low. With the increasing of the content of LiC104, the proportion of the first type will increase.4. There is a dynamic equilibrium between the carbonyls and lithium ions, in terms of association and de-association. The lithium ion is found to be quite "mobile". It can exchange from one association site to another site, which is believed to be the reason that high Tg polymer/Lithium-salt can act as polymer electrolyte.PART II: NMR study on starch-sodium acrylate grafted copolymerThe domain-structure of a series of starch/poly(sodium acrylate) grafted samples, with comparison with starch, poly(sodium acrylate) and starch/poly(sodium acrylate) blend, was studied by high-resolution solid-state ¹³C NMR spectroscopy at room temperature. The crystallinity of starch was found to decrease greatly in the graftedand blended samples. The obtained values of 1H spin-lattice relaxation time in rotating frame T1p and 1H spin-lattice relaxation time Ti showed that the starch and poly(sodium acrylate) components in both grafted and blended samples have the compatibiltiy on nm scale. In the 13C CP/MAS spectra, the chemical shift of the carbonyl group of poly(sodium acrylate) is found to be dependent on the composition of the grafted samples. This result indicates further that the starch and the poly(sodium acrylate) components of the grafted samples exhibit compatibility on the moelcualr level, which is better than that of the blend sample.