Polystyrene block copolymers, scattering

Sauer BB, Yu H, Tien CF, Hager DF (1987) A surface light scattering study of a poly (ethylene oxide)-polystyrene block copolymer at the air-water and heptane-water interfaces. Macromolecules 20 393 00... 

Borsali, et al. applied NSE to a polystyrene perdeuteropolystyrene block copolymer and to a mixture of polystyrene and perdeuteropolystyrene copoly-mers(85). By using a benzene perdeuterobenzene contrast-matching solvent, it was possible to arrange matters so that fluctuations in the number density of the block copolymer scattered no neutrons. Under these conditions, NSE spectra revealed a single mode for the block copolymer with relaxation rate linear in q and a nonzero intercept as 0. NSE spectra of the homopolymers instead revealed a mode with relaxation rate linear in and a zero intercept as 0. This result is very close to the predictions of Pecora(l-3) as confirmed with light scattering by Han and Akcasu(l 1) and Ellis, et a/.(14), but here the incident neutron waves had X = 8.5A, and the observed time range was 0.3-17 ns. 

The main experimental techniques used to study the failure processes at the scale of a chain have involved the use of deuterated polymers, particularly copolymers, at the interface and the measurement of the amounts of the deuterated copolymers at each of the fracture surfaces. The presence and quantity of the deuterated copolymer has typically been measured using forward recoil ion scattering (FRES) or secondary ion mass spectroscopy (SIMS). The technique was originally used in a study of the effects of placing polystyrene-polymethyl methacrylate (PS-PMMA) block copolymers of total molecular weight of 200,000 Da at an interface between polyphenylene ether (PPE or PPO) and PMMA copolymers [1]. The PS block is miscible in the PPE. The use of copolymers where just the PS block was deuterated and copolymers where just the PMMA block was deuterated showed that, when the interface was fractured, the copolymer molecules all broke close to their junction points The basic idea of this technique is shown in Fig, I. 

Consider a polystyrene-( )-polybutadiene star block copolymer with four arms coupled by a central Si-atom. Or consider a metal catalyst (e.g., Au) supported in activated carbon. Then the scattering of only the selected element (Si, Au, respectively) can be extracted [242], Even the distribution of the elements in the material can be mapped based on ASAXS data. A concise review of the ASAXS method in combination with AXRD and AWAXS has been published by Goerigk et al. [243]. 

Here, we focus on one class ofblock copolymers synthesized by this method polystyrene-6-poly(vinylperfluorooctanic acid ester) block copolymers (Figure 10.33). After describing the synthesis and characterization, we will treat some properties and the potential applications of this new class ofblock copolymers. The amphiphilicity of the polymers is visualized by the ability to form micelles in diverse solvents that are characterized by dynamic light scattering (DLS). Then the use of these macromolecules for dispersion polymerization in very unpolar media is demonstrated by the polymerization of styrene in 1,1,2-trichlorotrifluoroethane (Freon 113). 

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. ... 

A series of block copolymers were studied by SANS in which the C02-philic PFOA block length was varied (16,600 < Mn (g/mol) < 61,100) and the C02-phobic polystyrene block was held constant (Mn = 3,700 g/mol). Fitting of the scattering curves to a core shell model predicts spherical structures with an average degree of association of 7 surfactant molecules per micelle. This value was constant for the series of materials as would be expected... 

Fig. 32. (a) Two-dimensional small-angle X-ray scattering pattern of an SBS block copolymer with 33% aliphatic oil content and stretched to a draw ratio X = 4. (b) Long period L in SBS Meek copolymers as a function of the draw ratio X (pure SBS and SBS with different oil contents), (c) height of the polystyrene cylinders h in SBS block copolymers as a function of the draw ratio X (pure SBS and SBS with different oil contents), (d) diameter of the polystyrene cylinders 2r in SBS block copolymers as a function of the draw ratio X (pure SBS and SBS with different oil contents)... 

Fig. 39. Small-angle X-ray scattering profiles of a polystyrene/polybutadiene block copolymer (molecular weight of the blocks M = 18600) at different temperatures T above the order/disorder transition temperature. The points indicate the measured intensity values while the solid lines are obtained by fitting a one-parametric theoretical model...

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],...

Figure 2. Evolution of hydrodynamic radius versus DMSO volumic fraction for different block-copolymers., O Dex-block-PS27a d. Dex-block-PSjjs. Dotted curve indicates the area where no scattered signal could be detected. Schematical morphologies are inserted in the graph. Red colour illustrates dextran, blue colour polystyrene.

Block copolymers of polystyrene and PFOA, PS-6-PFOA, in CO2 were also extensively studied by SAXS, SANS (46, 47), high-pressure, high-resolution (HPHR) NMR (48) and pulsed magnetic field gradient (PFG) NMR (49). Neutron scattering data (46) showed that the micellar size increases with the PFOA mass, when holding MW of the PS component constant. The effect of CO2 density (0.27 to 0.84 g.cm ) at constant temperature (60 °C), and of temperature (29.5 to 76.2 °C) at constant CO2 density (0.733 g. cm ) was studied on PFOA/CO2 systems by HPHR NMR (48). 

UT1 Utiyama, H., Takenaka, H., Mizumori, M., and Fukuda, M., Light-scattering studies of a polystyrene-poly(methyl methacrylate) two-block copolymer in dilute solutions. 

Polystyrene oligomer (M. = 0.5K g mole ) was added to the block copolymer solutions to study the solubilization of homopolymers within the micelles. Separate concentration series were run for normal (PSH) and deuterated (PSD) oligomers and the isotopic difference between the oligomers should have a major effect on the scattered... 

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