Structure in Thin and Ultrathin Spin-Cast Polymer Films

Abstract

The molecular organization in ultrathin polymer films (thicknesses less than 1000 angstroms) and thin polymer films (thicknesses between 1000 and 10,000 angstroms) may differ substantially from that of bulk polymers, which can lead to important differences in resulting thermophysical properties. Such constrained geometry films have been fabricated from amorphous poly(3-methyl-4-hydroxy styrene) (PMHS) and semicrystalline poly(di-n-hexyl silane) (PD6S) by means of spin-casting. The residual solvent content is substantially greater in ultrathin PMHS films, which suggests a higher glass transition temperature that results from a stronger hydrogen-bonded network as compared with that in thicker films. Crystallization of PD6S is substantially hindered in ultrathin films, in which a critical thickness of 150 angstroms is needed for crystalline morphology to exist and in which the rate of crystallization is initially slow but increases rapidly as the film approaches 500 angstroms in thickness.

Engineering Chemistry of Electrospun Nanofibers and Interfaces in Nanocomposites for Superior Mechanical Properties

“…When attractive interactions are present at a polymer-nanofiller interface, confinement lead to enhancements rather than depressions in T g relative to neat values (33,34). At the interface, formed bonds restrain cooperative segmental mobility and lead to an increased T g (35,36).…”

Solvent retention in thin polymer films studied by gas chromatography

“…The final thinning of the film is then due solely to solvent evaporation [2]. Most of the solvent evaporates during the last step of the spin-coating, but it is known that some solvent is still present in the films at the end of the spin-coating [1,3,4] and that the polymer chains are quenched in a nonequilibrated state [5][6][7][8]. Spin-coated films are therefore generally annealed above the glass transition temperature of the polymer to dry the films and let the polymer relax to equilibrium.…”

“…For example, they are used as resists and interlayer dielectrics in microelectronics fabrication, alignment layers in liquid crystal displays, and lubricants in magnetic information storage devices. In these applications, the polymer chain orientation and state of organization play an important role in determining the final properties of the films [1].…”

Recent Approaches to Controlling the Nanoscale Morphology of Polymer-Based Bulk-Heterojunction Solar Cells

“…This also occurred in the film produced with a higher loading of PCBM (1:4), which displayed an amorphous phase before annealing [89]. Despite prolonged heat treatment, trace amounts of the casting solvents could still be found in the active layer [90,91]. The presence of residual solvent after thermal annealing leads to the formation of large PCBM agglomerates that cause extensive phase separation, thereby reducing the local photovoltaic efficiency of the device.…”