Fig. 2

Size and local glass transition temperature of ionic aggregates in PI–xNA. a Experimental SAXS patterns for PI–xNa simulated using the Yarusso–Cooper model. b The size of the ionic aggregate is almost constant against the neutralization level. c Chemical structures of spin probes and suggested locations of the probes for PI–90Na based on analysis of the ESR results. nDSA (n = 5, 7, 10, and 12) are localized at polar ionic aggregates, while 10DND is dispersed in the nonpolar PI matrix. d High A_zz values of 5DSA and 7DSA demonstrate localization of the nitroxide section of the probe inside the ionic aggregates. The T_g of the ionic aggregate is higher by ~10 °C than that of the PI matrix. The COOH group of the nDSA probe is assumed to localize at the center of the ionic aggregate, as illustrated in c