Dielectric spectroscopy and temperature modulated DSC are employed to study
the molecular dynamics (dynamic glass transition) of oligomeric poly(propy
lene) glycol (PPG) melts (M-W = 1000, 2000, 3000 and 5000) confined to nano
porous glasses (pore sizes 2.5, 5.0, 7.5 and 20 nm). For large pore sizes a
speeding up of the molecular dynamic compared to the bulk state is observe
d which is already known for low molecular glass forming liquids. For small
er pore sizes the molecular dynamics is slower than in the bulk. The observ
ed behavior is nearly independent of the molar mass and of the treatment of
internal glass surfaces. The experimental results are discussed in the fra
me of an interplay of confinement and packing effects. Moreover a length sc
ale of 1.5 nm is estimated as lower bound for the glass transition.