Kinetics of Chain Organization in Ultrathin Poly(di-n-hexylsilane) Films

Abstract

The effect of film thickness on the organization kinetics of ultrathin (50-1000 Å thick) spin-cast polymer films was studied using poly(di-n-hexylsilane) and UV absorption spectroscopy. We found an extensive reduction in the crystallinity as well as a reduction in the rate of crystallization for film thicknesses below 500 Å resulting from the constrained geometry. Modeling using polymer crystallization theories elucidated the surface-induced phenomena. We found that the dimensionality of the growth depended both on the film thickness and on the crystallization temperature. At low crystallization temperatures (below 0°C) and for films thicker than 220 Å, the nucleation is bulk and the growth is three-dimensional. However, at higher crystallization temperatures (above 3°C) and for low film thickness (below 150 Å), the growth is one-dimensional and heterogeneous nucleation becomes important. For 500 Å thick films, the transition between the two nucleation regimes occurs abruptly around 3°C. Experimental SectionSubstrate Preparation. The poly(di-n-hexylsilane) used in this study was synthesized as reported previously. 17 The weight-average molecular weight was 2.6 × 10 6 and the polydispersity 2.4. Solutions of the polymer were made in isooctane (2,2,4-trimethylpentane, 99+%, Aldrich Chemical Co.) in concentrations ranging from 0.1 to 2 wt %. The isooctane was used as received.

Vertical confinement and interface effects on the microstructure and charge transport of P3HT thin films

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Confined crystallization of nanolayered poly(ethylene terephthalate) using X-ray diffraction methods

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SAXS study on the crystallization of PET under physical confinement in PET/PC multilayered films

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