Effect of Cation Exchange Capacity on the Structure and Dynamics of Poly(ethylene oxide) in Liþ

ABSTRACT: Molecular dynamics computer simulations are used to study the structure and dynamics of 1-nm wide films of poly(ethylene oxide) (PEO) confined between mica-type layered silicates of different cation exchange capacities (CEC). The simula-tion setup mimics experimental systems formed by intercalation of PEO in montmor-illonite alumino-silicates with varied inherent charges. It is shown that the presence and population of lithium has a significant influence on the behavior of the system, in addition to the confinement-induced effects caused by the extreme spatial restric-tion. The structural features of the confined PEO are strongly altered with the num-ber of Liþ, which determines the polymer/inorganic interactions. The combination of the nanoconfinement and the presence of lithium preclude regular ordered arrange-ments of PEO, similar to those observed in the bulk unconfined polymer. The segmental dynamics of PEO in confinement are also greatly influenced by the presence of lithium, because of the strong interaction between Liþ and the oxygen of the PEO backbone