Investigation of copolymer-micellar system EO37PO56EO37 by low-frequency internal friction

The internal friction and relative modulus are measured for a copolymer-micellar system EO37PO56EO37 at different concentrations. At concentration above ∼21.5 wt%, we have evidenced the presence of two first-order phase transitions, corresponding to the sol-gel transition and the gel-sol transition, respectively. The former is related to the micelle crystallization, while the latter is due to the formation of worm-like micelles. It is found that the formation of crystalline phase strongly depends on the interpenetration and entanglement of the PEO chains. Our work confirms that internal friction technique is sensitive to structural changes of micellar systems.