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 in 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 corrected. 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.