Molecular solution casting

In this paper, UV-visible absorption spectra and X-ray diffraction experiments of single crystals and solvent cast films of the azobenzene amphiphiles, CnAzoCmN+Br, were systematically investigated. Structural characterization of the cast bilayer films are discussed in comparison with aqueous solutions and single crystals. Some novel functional properties of the cast films are described, too. We also emphasize that the two-dimensional molecular assemblies, cast films and crystals of bilayer-forming amphiphiles, are suitable candidates for "crystal engineering" because of their simple structures compared with usual three-dimensional molecular crystals. 

Monodisperse analogs of such ir-electron systems, PPV oligomers (molecular glasses) were studied by Bazan and coworkers [217]. The films prepared from 192 by solution casting showed completely amorphous structure due to a tetrahedral structure of the molecule and OLEDs ITO/PVK/192/Al-emitted green light with an efficiency up to 0.22 cd/A (Chart 2.42). 

Experiments indicate that the critical strain-to-failure is also affected by the average molecular weight and by material processing history. McGrath40 reported strain-to-break of a non-crystalline ionomer (a poly(arylene-ether) random copolymer, biphenyl sulfone in H form, or bi-phenyl sulfone in H form (BPSH)) is proportional to the length of the chain. We found in our laboratory that the casting procedure also affects the strain-to-break of the solution-cast ionomer film. As shown in Fig. 19, a Nation film cast at near room... 

The first optical absorption bands of benzene and pyridine are known to occur near 5 eV. The optical data on 1000 A thick, solution cast, PS and PVP as well as on the model molecules ethyl benzene and 2-ethyl pyridine in the gas phase were recorded on a Cary 14 double beam instrument. The data are therefore limited to >1 u <6 eV by the optics of the instrument. Condensed molecular solid spectra were not necessary since the photoemission studies had already shown that the polymer and condensed molecular spectra were equivalent. Therefore a comparison of gas-phase model-molecule spectra with that of the corresponding polymer spectra was sufficient. 

Under certain conditions, rather well-defined ring and honeycomb patterns can be formed by solution casting of thin films. Recently Nolte described the formation of isolated rings with diameters of several micrometers formed by stacked porphyrin molecules [287], Phase segregation or eruption of gas bubbles was assumed to be responsible for the peculiar assembly of the porphyrin wheels . However, the regular shape of the solute molecules was also considered to be of crucial importance, Another example is the honeycomb pattern of star shaped poly(styrene)-block-poly(-p-phenylene) films described by Francois [288], In this case, the peculiar molecular shape was emphasized to be of crucial importance besides the proper choice of solvent and evaporation conditions [289],... 

Polymer electrolyte complexes of PM MS or PAGS with LiC104 were made by solution casting from methanol or THF. In some cases, PEO with a number-average molecular weight (M ) of 4 X 10 was added to enhance the toughness of the films. The polymer-electrolyte mixtures were dried under vacuum at 60 °C for several days. 

Poly(2a) and poly(2b) are partly insoluble in toluene. In contrast, poly(2c) and poly(2d) are totally soluble in toluene, because they have a long, flexible alkyl chain. The molecular weights of these polymers are fairly high, 5 X 10 -3 X 10 Free-standing films can be obtained from poly(2c) and poly (2d) by solution casting (usually, a molecular weight of over 10 is necessary for the formation of free-standing film from a substituted polyacetylene). All the poly(2)s are yellow solids. 

Via solution casting (Fig. 10.24h) a droplet of solvent containing the molecules is deposited onto the substrate and the solvent evaporates. Typically, millimolar solutions are used for this method, which therefore only need small quantities of substance. The solvent has to be chosen not to adsorb on the substrate and leave enough time (prior to evaporation) to allow molecular organization. This method leads to reproducible results, also for supermolecules. Solution casting on a heated substrate is often referred to as sizzling [137]. 

To date, a variety of lithographic techniques, including advanced soft- and photolithographic methods, have been extensively used for constructing molecular architectures at multiple length scales [100]. Thanks to their versatility, such approaches can be easily transferred to different substrates and molecular materials, including SMMs. For instance, solution-cast thin films of... 

Here excimer fluorescence from phenyl-phenyl interactions in PS is the main experimental observable. This blend was selected because it has been demonstrated by numerous other techniques that miscible one-phase blends may be prepared by solution casting from toluene solvent. [2,3] Moreover, the blend may be forced to phase separate by thermal means, leading to a two phase system. In addition, we will consider results for blends of poly(2-vinyl naphthalene) (P2VN) with low molecular weight poly(cyclohexyl methacrylate) (PCMA) and polystyrene (PS). 

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