A RAMAN-SPECTROSCOPIC INVESTIGATION OF METHOXYL END-CAPPED PPO DOPED WITH NACF3SO3

Raman spectroscopy was used to study ionic association and polymer con formation in methoxyl end capped PPO (M-PPO) doped with NaCF3SO3, for temperatures ranging from 230-340 K. M-PPO of molecular weights 400 to 2000, pure and doped with sodium triflate of concentration O:M = 15:1 , were studied in order to investigate the importance of the end group s for ionic solvation. It is found that in M-PPO, in contrast to OH-te rminated PPO, the number of dissociated ions is independent of molecul ar weight. Moreover, the ion-association in the M-PPO systems was foun d to be comparable to that reported for OH-PPO of molecular weight 400 0 indicating that the latter is an excellent low molecular analogue to higher molecular weight systems. Furthermore, the absence of a distin ct polarised metal-oxygen breathing mode in the M-PPO salt complexes i ndicates a polymer-ion interaction different from the symmetric config urations of chains wrapped around cations as suggested for PEO based p olymer electrolytes. The solvation model of cations forming cross-link s via coordinations to ether oxygens of adjacent chains is favoured. ( C) 1998 Published by Elsevier Science Ltd. All rights reserved.