Jean-Loup Masson | PubMed Health

PubMed2002

Hole formation in thin polymer films: a two-stage process.

Thin, supported liquid films are known to rupture, creating holes throughout the film, due to defects or to van der Waals interactions. We show that the hole formation process before rupturing occurs in two stages, each characterized by distinct dynamical and morphological features. The time scale for the formation process is orders of magnitude slower than the translational (reptation) relaxation time of the individual chains. This has implications regarding the transition from the formation regime to subsequent hole growth regime on the underlying substrate.

Journal Article↗

PubMed2002

Viscosity of entangled polystyrene thin film melts: Film thickness dependence.

We determined the low-shear effective viscosity of entangled polystyrene thin film melts, in the thickness range of 27<h<100 nm, on SiO(x)/Si substrates. This was accomplished using a method based on the notion that thin liquid films can become unstable and rupture due to defects or to destabilizing, long-range van der Waals interactions (dewetting). The holes that are created in the film subsequently grow at a rate determined by a balance between the capillary driving forces and the viscous resistive forces. Based on the velocity of growth of holes on the substrate, we show that the viscosity decreases appreciably with decreasing thickness for 25<h<50 nm. These results are consistent with studies which suggest that the glass transition of entangled polystyrene thin film melts on SiO(x)/Si substrates exhibit an apparent decrease with decreasing film thickness over the same range of h.

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