Spin cast films

The annealing experiments on spin cast films near Tg show a drop in Ie/Im, although after 24 hours of annealing Ie/Im is still higher than for a solvent cast film that has undergone no radial stress. This implies that non-equilibrium chain structures still exists in the spin cast films even after long annealing times. 

The morphology of spin-cast film, thickness of 180 nm, from polycaprolactone shows many spherulitic structures with fibrillar nanostructures formed of lamellae lying edge on (about 10 nm thick) and areas with lamellar sheets lying flat on. Different crystalline structures are found when the sample is melted and crystallized as a function of temperature. These two studies reinforce the complex inner relationship between physical treatment and nanostructure. 

For the pairs with relatively short PS and PEG chains (e.g., 15a 16a and 15b 16b), no microphase separation was observed in the corresponding spin-cast films (Li et al. 2005). The AFM image of 15b 16b was drastically different, although... 

At 23°C. Measurements were also performed at lower and higher temperatures. d As a spin-cast film. 

In the highly regioregular polymer 522, in its pristine amorphous form, the absorption maximum of spin-cast films is 493 nm (2.86 eV) (94MM6503 01JPC(B)7624). On treating the films with chloroform vapor, the maximum was shifted to 602 nm (2.06 eV), and the spectrum showed a fine vibronic structure with AE = 0.19 eV, typical of a more-planar ordered conformation. 

A. Satrijo, T. M. Swager, Facile Control of Chiral Packing in Poly(p-phenylene-vinylene) Spin-cast Films, Macromolecules, 2005, 38, 4054-4057. 

Figure 26 Emission spectra (PL, EL) in PC at room temperature of 40 wt% TPD donor solution with a 40 wt% of PBD acceptor added. The photoluminescence (PL) spectrum excited at 360 nm, the electroluminescence (EL) spectra (I, II) originate from the recombination radiation in a 60 nm thick film, taken at two different voltages. Absorption (Abs) and PL spectra (excitation at 360 nm) of (75wt% TPD 25wt% PC) and (75wt% PBD 25wt% PC) spin-cast films are given for comparison. Molecular structures of the compounds used are given in the upper part of the figure TPD [N,Nf-diphenyl-A v/V/-bis(3-methylphenyl)-l,l -biphenyl-4,4 diamine PBD [2-(4-biphenyl)-5-(4- er .-butylphenyl)l,3,4-oxadiazole PC[bisphe-nol-A-polycarbonate]. Adapted from Ref. 112.

Polyimides for microelectronics use are of two basic types. The most commonly used commercial materials (for example, from Dupont and Hitachi) are condensation polyimides, formed from imidization of a spin-cast film of soluble polyamic acid precursor to create an intractable solid film. Fully imidized thermoplastic polyimides are also available for use as adhesives (for example, the LARC-TPI material), and when thermally or photo-crosslink able, also as passivants and interlevel insulators, and as matrix resins for fiber-reinforced-composites, such as in circuit boards. Flexible circuits are made from Kapton polyimide film laminated with copper. The diversity of materials is very large readers seeking additional information are referred to the cited review articles [1-3,6] and to the proceedings of the two International Conferences on Polyimides [4,5]. 

Organized azo-molecular assemblies allow for the study of photoisomerization and photo-orientation in sterically and orientationally well-defined media, such as LBK multilayers, the molecular-interactions-based order of which can be altered by photoisomerization of the azo units.In this chapter, we also discuss the photoisomerization-induced changes in the structural and optical properties of highly organized organic films containing azobenzenes. Photoisomerization and photo-orientation of azobenzenes is compared in amorphous spin-cast films, in LBK supramolecular assemblies, and in self-assembled monolayers. 

This chapter is organized as follows. Section 4.2 addresses the study of photoisomerization and photoinduced orientation of azobenzene molecules at the molecular level in SAMs of azo-silane molecules. Section 4.3 discusses photoinduced effects in supramolecular assemblies, i.e., LBK multilayer structures containing azobenzene molecules, and compares the photoinduced movement of azobenzenes in these structures to that observed in spin-cast films. Section 4.4 focuses on the isomerization and sub-Tg photoinduced orientation in a series of very high Tg (up to 350°C) nonlinear optical polyimide and thermoplastic donor-embedded polyurethane polymers containing azo dye, especially focusing on polymer structure-Tg-photoinduced molecular movement relationships. Section 4.5 describes pressure effects on photoisomerization and photo-orientation in films of a PMMA polymer containing azo dye. Finally, we make some concluding remarks in Section 4.6. 

The electroluminescence (EL) and photoluminescence (PL) spectra of spin-cast films are also morphologically dependent. It is found that within the CLA region, the EL and PL spectra of spin-cast MEH-PPV films are strongly dependent on spin speed (Fig. 6.19). It is consistently observed that when the polymer solution is coated at high speeds (e.g., 4000-8000 rpm, 0.7 wt%), the resulting devices have... 

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