Morphology microphase-separated

Dais membranes are reported to be much less expensive to produce than Nation they are also reported to exhibit a rich array of microphase-separated morphologies because of the ability to tailor the block length and composition of the unsulfonated starting polymer. The main drawback of employing hydrocarbon-based materials is their much... 

Table 2 contains the characteristics of the amic ester-aryl ether copolymers including coblock type, composition, and intrinsic viscosity. Three series of copolymers were prepared in which the aryl ether phenylquinoxaline [44], aryl ether benzoxazole [47], or aryl ether ether ketone oligomers [57-59] were co-re-acted with various compositions of ODA and PMDA diethyl ester diacyl chloride samples (2a-k). The aryl ether compositions varied from approximately 20 to 50 wt% (denoted 2a-d) so as to vary the structure of the microphase-separated morphology of the copolymer. The composition of aryl ether coblock in the copolymers, as determined by NMR, was similar to that calculated from the charge of the aryl ether coblock (Table 2). The viscosity measurements, also shown in Table 2, were high and comparable to that of a high molecular weight poly(amic ethyl ester) homopolymer. In some cases, a chloroform solvent rinse was required to remove aryl ether homopolymer contamination. It should also be pointed out that both the powder and solution forms of the poly(amic ethyl ester) copolymers are stable and do not undergo transamidization reactions or viscosity loss with time, unlike their poly(amic acid) analogs.

F-BDAF Tg for various blend compositions, see Fig. 14. The microphase-separated morphology further manifests itself in the self-adhesion behavior of polyimide films derived from such mixtures. For mixture containing at least 25 wt% of the flexible component, peel tests of polyimide bilayer samples prepared by solution casting, bulk failure of the test specimens was observed. Since the flexible component contained fluorine, the samples could be examined by X-ray photoelectron spectroscopy to determine the surface composition. At only 10% loading, the flexible component comprised 100% of the top 75 A of the sample. The surface segregation of the flexible component is believed to be responsible for the adhesion improvements. 

Microstructures of (1) PE-g-PPG polymer hybrid and (2) the blended sample of PE and PPG were observed by transmission electron microscopy (TEM) images after the preparation of press sheets of each polymer sample at 200 °C. The TEM images of the resulting polymer hybrid reveal the nanometer level microphase-separation morphology between the PE segment and the PPG segment compared with the PE/PPG blended polymer. From the result, the nanodispersion of different segments in polymer hybrids is possible, but different from the blended polymer sample (Fig. 8). 

Block copolymers with well-defined segments often show microphase-separated morphologies (such as lamellar layers, hexagonal ordered cylinders, and micelle formation). If we use SCLCP blocks together with non-liquid crystalline segments, the mesophases are formed within one of the separated microdomains. If the non-SCLCP block has a higher Tg than the phase transition temperature of the mesophase, the amorphous block should physically support the SCLCP microdomains, forming a self-supported SCLCP system. 

In even the simplest pure diblock and triblock copolymer melts, numerous distinct microphase-separated morphologies have been observed, as depicted at the top of Fig. 13-4 (Winey et al. 1992 Forster et al. 1994 Hadjuk et al. 1994 Schulz and Bates 1996). The simplest types of domain shapes are spheres, cylinders, and lamellae. For a pure AB diblock... 

Fig. 3.56 Tapping mode AFM phase image a thin (dMm <30 nm) poly(isoprene)-b-poly (ferrocenyl dimethylsilane) (36 kg/mol/12 kg/mol) film displaying different microphase separated morphologies as a function of film thickness. Reprinted with permission from [116]. Copyright 2000. American Chemical Society...

Visualization of Microphase Separated Morphology of Films of Polystyrene-b-polyisoprene-b-polystyrene... 

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