ISSN:
0887-6266
Schlagwort(e):
ionic conduction
;
poly (propylene oxide)
;
N,N-dimethylformamide
;
lithiumthiocyanate
;
dissociation equilibrium
;
infrared spectroscopy
;
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Dissociation equilibria of lithiumthiocyanate (LiSCN) in N,N-dimethylformamide (DMF) solutions of poly (propylene oxide) (PPO) were investigated by using infrared spectroscopy. The stretching bands due to the thiocyanate ions SCN-1 and the LiSCN ion pair were found at 2058 and 2072 cm-1, respectively. At high LiSCN concentration C of ca. 20 wt %, another weak band due to the dimer (LiSCN)2 was observed. From the ratio of the areas of the absorption bands, the dissociation constant K1 for the equilibrium LiSCN ↔ Li+ + SCN-1 and that K2 for (LiSCN)2 ↔ 2LiSCN have been determined. With increasing DMF content, K1 increases from 1 × 10-4 for bulk PPO to 4.8 × 10-1 for pure DMF at 299 K. Log K1 is not linear against inverse of the dielectric constant ∊ of the medium and decreases with increasing temperature. The enthalpy (ΔH) and entropy (ΔS) changes for the dissociation of LiSCN are both negative. ©1995 John Wiley & Sons, Inc.
Zusätzliches Material:
11 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/polb.1995.090330609
