Solvent casted films

In order to test the tissue compatibility of tyrosine-derived poly-(iminocarbonates), solvent cast films of poIy(CTTH) were subcutaneously implanted into the back of outbread mice. In this study, conventional poly(L-tyrosine) served as a control (42). With only small variations, the experimental protocol described for the biocompatibility testing of poly(N-palmitoylhydroxyproline ester) (Sec. III. 

Since poly(L-tyrosine) cannot be processed into shaped devices, compressed pellets rather than solvent cast films were used as control implants. Poly(L-tyrosine) formed strikingly yellow, moderately inflamed patches that remained at the implantation site throughout the 1-year study. Contrary to soluble proteins or peptides that ar rapidly degraded by enzymes, implants of conventional poly(L-tyro-sine) were evidently nondegradable over a 1-year period. At wee 56 all poly(L-tyrosine) implants were infiltrated by a moderate n ber of inflammatory cells. 

Poly(CTTH) (Figs. 6 and 7) was also used as a model compound for the preliminary evaluation of the in vitro degradability of tyro-sine-derived poly(iminocarbonates) Solvent cast films of poly(CTTH)... 

The electrochemical behavior of the C70 solvent-cast films was similar to that of the C60 films, in that four reduction waves were observed, but some significant differences were also evident. The peak splitting for the first reduction/oxidation cycle was larger, and only abont 25% of the C70 was rednced on the first cycle. The prolate spheroidal shape of C70 is manifested in the II-A isotherm of C70 monolayers. Two transitions were observed that gave limiting radii consistent with a transition upon compression from a state with the long molecnlar axes parallel to the water snrface to a state with the long molecnlar axes per-pendicnlar to the water surface. 

C60 has been used to produce solvent-cast and LB films with interesting photoelec-trochemical behavior. A study of solvent-cast films of C60 on Pt rotating disc electrodes (RDEs) under various illumination conditions was reported [284]. Iodide was used as the solution-phase rednctant. The open-circuit potential shifted by 74 mV per decade of illumination intensity from a continuous wave (cw) argon-ion laser. The photocurrent versus power was measured at -0.26 V under chopped illumination (14-Hz frequency, vs. SCE) up to 30 mW cm and was close to linear. The photoexcitation spectrum (photocurrent versus wavelength) was measured at 0.02 V (vs. SCE) from 400 to 800 mn and found to be... 

Solvent-cast films of tyrosine-derived polyiminocarbonates and polycarbonates were virtually indistinguishable in appearance and exhibited similar morphological features. When examined by X-ray diffraction, using an automated Scintag Pad V diffractometer all tested films were found to be completely amorphous. The lack of ordered domains in solvent-cast films seemed to be a general feature of tyrosine-derived polyiminocarbonates and polycarbonates, irrespective of the pendent chain configuration of the monomeric dipeptide. 

Two other features are notable in Table III. The swelling values for the compression molded samples (CM) run consistently less than those for the solvent-cast films. Apparently there is more "entrapment" of the amorphous portions within the crystallites during and after the molding. Secondly, the degradation experienced by the polymer hydrogenated at 69°C. (see Table II) instead of 52°C. is clearly demonstrated by the higher swelling value. 

Figure 7. X-ray fiber diagram of hydrogenated poly(5-methyl-l, 4-hexadiene). Solvent cast film strip cold drawn to four times its original length. Reproduced, with permission, from Ref. 19. Copyright 1976, John Wiley Sons, Inc.

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. 

UV-visible absorption spectrum of solvent 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. 

Cobalt(II) chloride was dissolved in poly(amide acid)/ N,N-dimethylacetamide solutions. Solvent cast films were prepared and subsequently dried and cured in static air, forced air or inert gas ovens with controlled humidity. The resulting structures contain a near surface gradient of cobalt oxide and also residual cobalt(II) chloride dispersed throughout the bul)c of the film. Two properties of these films, surface resistivity and bullc thermal stability, are substantially reduced compared with the nonmodified condensation polyimide films. In an attempt to recover the high thermal stability characteristic of polyimide films but retain the decreased surface resistivity solvent extraction of the thermally imidized films has been pursued. 

General Properties. It has been shown 16) that the incorporation of cobalt chloride into a poly(amide acid) solution and processing the solvent cast film to temperatures up to 300 c in an appropriate... 

It is interesting to note that, in most cases studied, the range of hydroxyl content in PS(OH) which allows the miscibility-to-complex transition to take place in solvent-cast films is almost the same as that allowing separate coils to transform to complex aggregates in solutions [143]. This agreement suggests that complexes formed in dilute solutions remain undestroyed during the process of solvent evaporation. 

The films prepared by melt prosing are very rapidly cooled to room temperature. Under these conditions no detectable crystallization in the polymer can develop, as is proved by x-ray examination. On the other hand, in the solvent-cast films chain mobility of the polycarbonate is enhanced by the presence of solvent and crystallinity can occur. In some extreme cases the solvent cast films are turbh ana the a ystallmn. can be a. nonstrated by x-ray photograms which showr x-ray patterns characteristic of crystallized polycarbonate. It is assumed that... 

Fig. 6.29 TEM image of a 30 70 mixture of a diblock with /PS < 0.5 (M = 94 kg mol fK = 0.83) and a longer one with fK > 0.5 (Mn = 176kgmol 1,/PS — 0.81) (Koizumi et al. 1994c). The solvent-cast film was annealed at 150 °C. Domains rich in the diblock with /ps < 0.5 (consisting of PS cylinders) are dispersed in the matrix of the diblock with /ps > 0.5, which forms a microstructure of PI spheres. TOKI4 and B2 are notations of the authors for the diblocks.

Addition of DPP to growing MPP at 60° C produced still another type of copolymer. Solvent-cast films of this material are transparent. The copolymer does not crystallize on heating, forms stable solutions in m-xylene, and has a single glass transition, at 190°C. The thermal behavior is similar to that of a random copolymer, but the NMR spectrum (Figure 7) is more nearly that expected of a block copolymer. The methyl proton peak is rather sharp with the chemical shift expected for... 

Recently, Lee, Kwak, and coworkers have reported on mechanochromic photoluminescent LC polymer 5 (Fig. 5) [32]. This poly(diphenylacetylene) derivative has flexible dimethyloctadecylsilyl side chains. A solvent cast film made from toluene solution of compound 5 shows a smectic LC phase above 5 °C and phase transition to the isotropic phase is not observed until 200 °C. The cast film of compound 5 shows a blue emission. An orange emission can be observed when mechanical stimulus is induced to the cast film of compound 5. In the emission spectra, an additional shoulder appears after the mechanical stimulus is induced. The longer wavelength component is attributed to forming intermolecular excimers. The sky blue emission is recovered by annealing of compound 5 in hexane. 

The infrared spectra for common rubbers have been reported in ASTM D3677 [12]. Most of these spectra were done either in solvent casting film or by pyrolysis. 

Is there any difference in the appearance of the solvent cast films of nylon and polystyrene ... 

---