Glass annealed films cast

Figure 9. X-ray diffraction scans from annealed films cast on glass...

The equilibrium diffusion coefficient De for glass and Teflon cast films is identical with that of mercury cast and annealed films. This, in fact, should be expected since after stress is relieved from glass and Teflon cast films upon absorption, the polymer molecules return to their normal orientation as in the mercury cast and annealed films. Therefore, the equilibrium diffusion coefficient is the same regardless of the casting surface. 

Two types of samples were prepared for detailed morphological examination. Sections of the as-polymerized material were examined directly by WAXS and DSC. Samples also were prepared by casting films from a solution of the polymer in dimethyl formamide (DMF) at 52°C. Solvent was allowed to slowly evaporate, and the films were dried by annealing for 670 hr at 52°C, followed by slow cooling to room temperature. Thin films suitable for electron microscopy were cast from 0.5 wt % polymer in DMF onto clean glass slides, and after 20 hr of annealing at 52°C, floated off on distilled water and mounted on 300-mesh copper grids. 

Fig. 37 AFM images of P3HT-PCBM (a-c) and P3HT-PCBG (d-f) blend films spin cast on glass. The images show unheated films (a and d), films annealed for 4 min at 140 °C (b and e), and films annealed for 1 h at 140 °C (c and f) [186]. (Reproduced by permission of The Royal Society of Chemistry)...

Nguyen and Kausch [1984] found that the presence of phenyl groups in poly(styrene-co-acrylo-nitrile), SAN, protects PMMA in the blend, during radiolysis (Table 11.9). SAN and PMMA were dissolved in dimethyl formamide, 50- J,m-thick films were cast, and then dried under vacuum. Transparent bar specimens were compression-molded from the film. Mixing the polymers by co-precipitation from methanol resulted in opaque samples. Gamma irradiations were done in evacuated and sealed glass tubes, at a dose rate of 3 kGy/h. Comparison of freshly irradiated samples with irradiated and annealed ones showed the absence of any post-irradiation effects. 

Polymerization of these films was carried out with tricosanoyl-10 12-diynoic acid creating a red (less ordered) and blue (more ordered) form. Bulk polymerized films were observed at the air/water interface and on glass substrates though with slightly differing intensities in their visible absorption spectra. It was clear that when monolayer films were polymerized and then compressed beyond the collapse point, the resultant film was significantly less ordered, as indicated by the predominance of the red conformer. Thus the molecular order of a polymerized film can be adversely affected by subsequent mechanical manipulation. In contrast to monolayers, solution cast films showed no polymerization under comparable conditions, but did do so once the film had been annealed. It would appear that annealing allowed the formation of a better oriented film. 

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