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We report on the effect of interfacial energy on the glass temperature, T g , of several amorphous polymers with various glass temperatures and polymer/substrate interactions confined within self-ordered nanoporous alumina (AAO). The polymers studied include poly(phenylmethylsiloxane) (PMPS), poly(vinyl acetate) (PVAc), 1,4-polybutadiene (PB), oligostyrene (PS), and poly(dimethylsiloxane) (PDMS). The segmental dynamics and associated T g 's are studied by means of dielectric spectroscopy. The interfacial energy for the polymer/substrate interface, γ SL , is calculated with Young's equation whereas the AAO membrane surface energy is obtained by measuring contact angles for several reference liquids. We find that interfacial energy plays a significant role in the segmental dynamics of polymers under confinement within AAO. There is a trend for a decreasing glass temperature relative to the bulk with increasing interfacial energy. PDMS exhibits the highest interfacial energy and the highest reduction in glass temperature within AAO. Other effects that may also contribute to changes in T g are discussed.

The dynamics of unentangled cis-1,4-polyisoprene confined within self-ordered nanoporous alumina (AAO) is studied as a function of molecular weight (5000–300 g/mol) and pore size (400–25 nm) with dielectric spectroscopy. The main effects are the pronounced broadening of both segmental and chain modes with decreasing AAO pore diameter. This suggests that the global chain relaxation is retarded on confinement. Remarkably, the distribution of relaxation times is broadened even within pores with size 50 times the unperturbed chain dimensions. The glass temperature is unaffected by confinement. These results are discussed in terms of confinement and adsorption effects. Confinement effects are negligible for the studied molecular weights. Chain adsorption, on the other hand, involves time and length scales distinctly different from the bulk that can account for the experimental findings.

We show that the vitrification of star-shaped polystyrene (PS), of functionality f and molecular weight per arm M w arm , thin films supported by silicon oxide, SiO x , is strongly dependent on M w arm and f. When f is small, the vitrification behavior is similar to that of linear-chain PS where the average glass transition, T g , decreases with decreasing film thickness (ΔT g < 0). However, for sufficiently large f and small M w arm , T g becomes independent of film thickness (ΔT g ≈ 0). In this region, where ΔT g ≈ 0, the star-shaped macromolecules self-assemble into ordered, periodic structures, similar to that of soft spheres or colloids, as revealed by simulations and experiments. This is identified as the soft-colloidal region. The transition from the linear-chain-like to the soft-colloidal-like region occurs over an intermediate range of functionalities and arm lengths; throughout this transition range ΔT g > 0. We show that the overall vitrification behavior of these thin film star-shaped polymers is due to competing entropic interactions associated with changes in f and M w arm . The vitrification behavior of thin star-shaped PS films on SiO x is summarized in terms of a "diagram of states".