Dramatic reduction of the effect of nanoconfinement on the glass transition of polymer films via addition of small-molecule diluent

The effect of nanoconfinement on the glass transition temperature T-g in thin polymer films is studied as a function of added small-molecule diluent or plasticizer. The decrease [increase]For examplein T-g found in nanoconfined, neat polystyrene [poly(2-vinyl pyridine)] is suppressed by added diluent, with 13-20 nm thick polystyrene films exhibiting bulk T-g upon addition of 9 wt % pyrene or 4 wt % dioctylphthalate. This is explained by a connection between the size scale of the cooperative dynamics associated with T-g, which decreases with added diluent, and the size scale of the nanoconfinement effect.