Polycarbonate, scattering from

Lm,W., Kramer,E. J. Small-angle X-ray scattering from amorphous polycarbonate. J. Appl. Phys. 44,4288-4292 (1973). 

FIGURE 1 Effect of (sequential) extrusion of MLV dispersions through polycarbonate membrane filters (Unipore) with pore sizes of 1.0, 0.6, 0.4, 0.2, and 0.1 ym on the mean liposome diameter. DXR-containing MLV (phosphatidylcholine/phosphatidylserine/ cholesterol 10 1 4) mean diameter of nonextruded dispersion about 2 ym pH 4. Mean particle size determined by dynamic Light scattering (Nanosizer, Coulter Electronics). (From Crommelin and Storm, 1987.)... 

Figure 1. Contour map of the uncorrected scattering (CuKa radiation) from extruded polycarbonate ( = 3)...

As crystalline materials melt, their appearance transforms from opaque to transparent because the ordered structure is lost Highly amorphous polymers, including acryhcs, polycarbonate, and polystyrene do not form crystals, so are transparent (Figure 4.6). An exception is crystalline polyester poly (ethylene terephthalate) used in fizzy drinks botdes, which is transparent because its crystals are too small to interfere with hght waves. Fillers and additives usually decrease the light transmission of a plastic by scattering incident light. 

There are also some scattered reports of chemically prepared micro- and nanostructured pure PPys, despite electrochemical syntheses are much more effective regarding this goal. Demoustier-Champagne et al. reported the formation of 15-pm diameter monodisperse PPy tubules by simultaneous diffusion of pyrrole and oxidant into a porous polycarbonate membrane. Finally, PPy microfibers were prepared from chloroform solutions by electrospinning. ... 

The size distribution of the liposomes is determined by dynamic light scattering (DLS) with a Dynapro apparatus (http //www.wyatt.com). DLS is a hydrodynamic method by which one determines the rate of diffusion of particles through the solvent. The hydrodynamic radius is defined as the radius of a theoretical hard sphere that diffuses with the same speed as the particle under examination. The measurement is performed at 25° and requires about 2 /ul of the extruded liposome suspension diluted in 18 /ul of liposome buffer (final lipid concentration in the range of 0.1 roM). Ten autocorrelation functions are sequentially measured, from which the size distribution of the liposome is determined using the Dynamics v5 software from Dynapro. A complete measurement takes a few minutes. Figure lA shows typical size distributions of extruded liposomes as determined by DLS. Figure IB shows how the actual hydrodynamic radius of the liposomes varies with the pore size of the polycarbonate filter. 

Figure 2.17a shows an example of the neutron scattering that results when DjO is preferentially absorbed by one segment in a polymer. These data were obtained from a polymer in which poly(ethylene glycol), PEG, segments are randomly inserted along the polymer chains composed mostly of hydrophobic groups, tyrosine-derived polycarbonates... 

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