EPR STUDIES ON TELECHELIC POLYMERS - CHARACTERIZATION OF ION MULTIPLETS

Endfunctionalized polyisoprenes (PI) and polystyrenes (PS) with either one sulfonate or ammonium end group and alpha,omega-macrozwitterionic PI and PS have been synthesized and investigated by CW-EPR using the spin probe technique. From the extrema separation of the temperature d ependent spectra a characteristic temperature, T-50C, is introduced wh ich can be employed as a measure for the temperature dependence of the chain end association in these telechelic ionomers. In this way it is shown that the mobility of an ionic 2,2,6,6-tetramethylpiperidine-N-o xyl derivative is dramatically restricted when compared to the corresp onding nonionic probe. For PI the reduction in probe mobility correspo nds to temperature shifts as high as 140 K relative to the dynamics of the polymer, indicating the presence of highly immobilized ion multip lets. As shown by the temperature dependent data, the method is sensit ive to additional immobilization of the ionic domains induced by bulky substituents adjacent to the ionic chain ends. Comparison of the EPR results with structural data from SAXS measurements reveals that the m ain factors governing the dynamics of multiplets are the chemical type of ionic end group and the nature of the polymer backbone. Analysis o f the EPR data for telechelic PS shows that in high-T-g polymers the d ynamics of the ionic aggregates occurs at comparable time scales as th e dynamics of the polymer backbone.