Effect of Ionic Radius in Metal Nitrate on Pore Generation of Cellulose Acetate in Polymer Nanocomposite.

To prepare a porous cellulose acetate (CA) for application as a battery separator, Cd(NO3)2·4H2O was utilized with water-pressure as an external physical force. When the CA was complexed with Cd(NO3)2·4H2O and exposed to external water-pressure, the water-flux through the CA was observed, indicating the generation of pores in the polymer. Furthermore, as the hydraulic pressure increased, the water-flux increased proportionally, indicating the possibility of control for the porosity and pore size. Surprisingly, the value above 250 LMH (L/m2h) observed at the ratio of 1:0.35 (mole ratio of CA: Cd(NO3)2·4H2O) was of higher flux than those of CA/other metal nitrate salts (Ni(NO3)2 and Mg(NO3)2) complexes. The higher value indicated that the larger and abundant pores were generated in the cellulose acetate at the same water-pressure. Thus, it could be thought that the Cd(NO3)2·4H2O salt played a role as a stronger plasticizer than the other metal nitrate salts such as Ni(NO3)2 and Mg(NO3)2. These results were attributable to the fact that the atomic radius and ionic radius of the Cd were largest among the three elements, resulting in the relatively larger Cd of the Cd(NO3)2 that could easily be dissociated into cations and NO3- ions. As a result, the free NO3- ions could be readily hydrated with water molecules, causing the plasticization effect on the chains of cellulose acetate. The coordinative interactions between the CA and Cd(NO3)2·4H2O were investigated by IR spectroscopy. The change of ionic species in Cd(NO3)2·4H2O was analyzed by Raman spectroscopy.

Facile control of nanoporosity in Cellulose Acetate using Nickel(II) nitrate additive and water pressure treatment for highly efficient battery gel separators.

We succeed in fabricating nearly straight nanopores in cellulose acetate (CA) polymers for use as battery gel separators by utilizing an inorganic hexahydrate (Ni(NO3)2·6H2O) complex and isostatic water pressure treatment. The continuous nanopores are generated when the polymer film is exposed to isostatic water pressure after complexing the nickel(II) nitrate hexahydrate (Ni(NO3)2·6H2O) with the CA. These results can be attributed to the manner in which the polymer chains are weakened because of the plasticization effect of the Ni(NO3)2·6H2O that is incorporated into the CA. Furthermore, we performed extensive molecular dynamics simulation for confirming the interaction between electrolyte and CA separator. The well controlled CA membrane after water pressure treatment enables fabrication of highly reliable cell by utilizing 2032-type coin cell structure. The resulting cell performance exhibits not only the effect of the physical morphology of CA separator, but also the chemical interaction of electrolyte with CA polymer which facilitates the Li-ion in the cell.

Highly selective polymer electrolyte membranes consisting of poly(2-ethyl-2-oxazoline) and Cu(NO3)2 for SF6 separation.

Polymer electrolyte membranes consisting of Cu(NO3)2 and poly(2-ethyl-2-oxazoline) (POZ) were prepared for SF6/N2 separation. It was anticipated that repulsive forces would be operative between the negative charge of water and the F atoms of SF6 when Cu(NO3)2 in the composite was solvated by water, and that the barrier effect of Cu(2+) ions would be activated. In fact, Cu(NO3)2 solvated by water in the POZ membrane was observed to have more higher-order ionic aggregates than free ions or ion pairs, as confirmed by FT-Raman spectroscopy. Thus, when Cu(NO3)2 solvated by water was incorporated into the POZ matrix, the N2/SF6 selectivity increased to 28.0 with a N2 permeance of 11.2 GPU at a POZ/Cu(NO3)2 mole ratio of 1:0.7. The coordinative interaction of Cu(NO3)2 with the carbonyl group in POZ was confirmed by FT-IR spectroscopy and TGA, and the film thickness of the membrane was determined from SEM analysis.