Phase separation atomic force microscopy

LEDs were fabricated with TA-PPP as the emissive layer. Single-layer devices of ITO/PEDOT/TA-PPP/Ca/Al were fabricated. PEDOT, poly(3,4-ethylenedioxythiophene), was used to enhance hole injection from the anode. Charge injections of the single layer LEDs were clearly hole dominant The barrier for electron injection, around 1.0 eV, is too high. Electron dominant materials such as DO-PF and 2-(4-t-butylphenyl)-5-biphenyloxadiazole (t-PBD) were used to enhance electron injection. The thin film of a TA-PPP and PF blend (95 5 weight ratio) was phase separated. Atomic force microscopy (AFM) showed PF spheres, close to 1 pm in diameter, dispersed in the TA-PPP matrix (Figure 6). This type of phase separation is common in blends of stiff and soft polymers. The PL emission of die blend film was characteristic of TA-PPP. However, once thermally treated, the spectrum shifted bathochromically much like PF. The EL spectrum from LEDs based on the blend thin film contained much emission from PF in the 500-700 nm regime. The device efficiency was about 0.43 cd/A. TA-PPP/PF double layer LEDs were also fobricated. But the efficiency was not improved because when PF was spin coated onto TA-PPP, the PF solution washed out most of the TA-PPP layer. 

In the present review, first we will describe how to fabricate artificial photosynthetic reaction center in nanometer scales by making use of phase separation in mixed monolayers of hydrocarbon (HC) and fluorocarbon (FC) amphiphiles [2,5,20-26] as shown in Fig. 2b [3]. The phase separated structures were studied by SPMs such as AFM, SSPM, and scanning near-field optical/atomic force microscopy (SNOAM) [27-33] as well as a conventional local surface analysis by SIMS [3,5], The model anionic and cationic HC amphiphilic... 

Nonconjugated poly[l,3-propanedioxy-l,4-phenylene-l,2-ethenylene(2,5-bis(tri-methylsilyl)-l,4-phenylene)- l,2-ethenylene-l,4-phenylene] (DSiPV) and conjugated MEH-PPV polymers are mixed by changing their weight ratios in 1,2-dichloroethane. The films of the blend polymers could be spin-cast from 1,2-dichloroethane solution with excellent reproducibility. AFM (atomic force microscopy) and SEM images show no indication of phase separation or layer formation due to the immiscibility of two polymers. The structures of DSiPV and MEH-PPV are shown in Fig. 24. 

Ratio TV, Longo ML. Obstructed diffusion in phase-separated 64. supported lipid bilayers a combined atomic force microscopy and fluorescence recovery after photobleaching approach. Biophys. J. 2002 83 3380-3392. 

Kuznetsov, Y.G. Malkin, A.J. McPherson, A. Atomic force microscopy studies of phase separations in macro-molecular systems. Phys. Rev. B. Condens. Matter 1998, 58 (10), 6097-6103. 

Summary Silicone copolymers are hybrid matmals with varying phase separation levels. The polymers themselves as well as surfaces formed by these copolymers were analyzed by a variety of polymer and surface characterization methods. Atomic force microscopy was found to be especially suitable for analysis of thin polymer films. Both surface and bulk properties are dominated by the domain size and the silicone content. 

The top panel of Fig. 3.2 presents a selection of results for the lateral organization of some simple one- and two-component lipid bilayers that have been investigated by computer-simulation calculations and atomic force microscopy. A pronounced degree of lateral heterogeneity in terms of lipid domains is found. The lipid domains are either solid hpid patches in fluid bilayers or fluid lipid patches in solid bilayers. In lipid mixtures, the domains may reflect incomplete phase separation. The sizes, the morphology, and the topology of the lipid domain patterns depend on the lipid composition and the thermodynamic conditions. The domains can be enhanced or suppressed by adding further lipid components or solutes [36]. 

A further refinement of the scale of phase separation was recently demonstrated by Xia and Friend using inkjet printing (IJP) and thereby doubhng the EQE [238]. As demonstrated by fluorescence and atomic force microscopies, this originates from a more rapid drying process of inkjet printed films as compared to spin cast ones (see Fig. 50). The small volume and hence the large surface to voliune ratio of each IJP droplet led to this fast evaporation and drying. 

Another technique of interest is the atomic force microscopy (AFM). The method can be used in any system where properties of the separated phases significantly differ. For example, the method was used to determine thickness of the interphase in blends of PA with soft elastomer. In this case the rigidity scanning procedure was the most appropriate. Since the difference in moduli... 

Properties of mixed polymer compositions are determined by many factors, among which in the first place should be allocated phase sfructure (ratio and the size of the phase domains). Therefore, at the first stage of the research attention has been paid to study the stmcture of formed compositions. In the investigation of samples with a low content of PHB (10-30% by weight) has been found that it forms a discontinuous phase, i. e., distributed in a continuous matrix PIB as separate inclusions of the order of 1-2 pm. The results of atomic force microscopy for the composition ratio of PHB-PIB 20 80 were shown in Figure 2.1. 

Kajiyama T, Tanaka K, Ohki I, Ge S-R, Yoon SJ, Takahara A (1994) Imaging of dynamic viscoelastic properties of a phase-separated polymer surface by forced oscillation atomic force microscopy. Macromolecules 27 7932-7934... 

Atomic force microscopy (AEM) is used to determine surface microstructure of hot-melt extrudates, can be used to identify phase separation or non-homogeneity of HME samples. The AFM-based assessment of APEexcipient combinations is a robust method to rapidly identify miscible and stable solid dispersions in a routine manner. It is a novel analytical method used for the optimization of HME processes. ... 

To obtain the morphology information, including phase separation and crystalline, we can now use microscopic techniques, atomic force microscopy, transmission electron microscopy, electron tomography, variable-angle spectroscopic ellipsometry. X-ray photoemission spectroscopy, and grazing-incidence X-ray diffraction. The detailed information of this characterization methods can be found from the specific reference (Li et al., 2012 Huang et al., 2014). 

Furthermore, AFM (Atomic Force Microscopy) studies have shown that during the film-forming process many conventional surfactants phase separate from the binder. When the surfactant has phase separated, the water flux may carry it to the film surface. Alternatively, it may accumulate in the interstices between... 

Atomic force microscopy measurements suggest the formation of a phase separated structure in that the hydrophilic domains are well dispersed and connected to each other [100]. 

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