Scattering from polystyrene block

The study by low-angle X-ray scattering, electron microscopy, and differential scanning calorimetry of the mesophases obtained by dissolution of BSB copolymers in preferential solvents for the polystyrene block and of dry BSB copolymers obtained by slow evaporation of the solvent from the mesophases has allowed to establish the respective effect of different factors which control the structure of the mesophases and their geometrical parameters. It has been shown that the nature, concentration, polymerization of the solvent, and temperature have the same effect on BSB copolymers as on SB copolymers35,88-91. ... 

Fig. 48a. Normalized inverse scattering intensity NS l(q, e) observed in the Monte Carlo simulation of a block copolymer model on the simple cubic lattice (see Fig. 44) plotted vs the normalized inverse temperature eN. b Reciprocal structure factor S (q ) -l(cxrcfes, left scale) and q ( squares, right scale) plotted vs temperature for a nearly symmetric diblock copolymer of polystyrene/poly (cis— 1,4) isoprene (Mw = 15 700). Filled symbols refer to cooling, open symbols to heating runs. The straight tine indicates the extrapolation to a spinodal temperature (T,) that occurs above the actual transition temperature (Tmst). where the data show a jump. From Stuhn et al. [323],...

Subtraction of solvent-induced background. Although the block-coUimation system used in the camera discussed above suppresses most of the parasitic scattering at low angles, several other effects may lead to a considerable backgroimd which must be subtracted carefully from the measured intensities. To assess this problem in further detail. Fig. 10 gives a comparison of the different contributions to the measured scattering intensity of a polystyrene latex of 150 nm diameter [73]. 

A more detailed interpretation of the internal structure of the PODMA domains is possible based on WAXS data for a semi-crystalhne block copolymer (Lam-20 nm) measured at room temperature using a Bruker D500 system (Fig. 12.8). Data for polystyrene and semi-crystalline PODMA homopolymers are shown for comparison. It is obvious that the scattering curve for the microphase-separated block copolymer can be interpreted as a superposition of contributions originating from both individual components. The first two peaks (1 32) at q 2.1 nm and q 4.3 nm indicate the nanophase separation and the lamellar packing of main and side chains in semi-crystalline... 

Richards and Thomason observed several peaks in the scattering curves from styrene-isoprene block copolymers, which indicate that the copolymer separates into two domains. By comparing the observed scattering curves with model calculations, the domains were characterized as a face-centred cubic array of polystyrene spheres in a polyisoprene matrix. The spheres had a radius of 130 A, were 383 A apart and there was a 29 A thick interfacial layer around them. 

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