Polystyrene-block-poly methyl

Lu, Z.-H., and Walker, G.C. (2009) Water-stable diblock polys1yrene-block-poly(2-vinyl pyridine) and diblock polystyrene-block-poly(methyl methacrylate) cylindrical patterned surfaces inhibit settlement of zoospores of the green alga Ulva. Biomacromolecules, 10, 1004—1012. 

Figure 15 Transmission electron micrograph of polybutadiene-block-polystyrene-block-poly (methyl methacrylate) B-S-M forming the banana morphology. Due to staining with OSO4 only the curved B cylinders are visible. (From Ref. 183, Copyright 1996 American Chemical Society.)...

When the homopolymer is comparable in size to the BC the homopolymer will segregate to the middle of the appropriate BC domain and produce a larger interlameUar spacing than the observed-for wet brush regime described previously. In this situation, described as dry brush the brush layer formed by the BC is not interpenetrated by the homopolymer. The latter forms a separate phase. This behavior has been illustrated in different mixtures, such as PS or PMMA homopolymers with symmetric short polystyrene-block-poly(methyl methacrylate) (PS-fc-PMMA) diblock copolymers where the... 

WOH Wohlfarth, Ch., Isopiestic vapor sorption measurements for solutions of a polystyrene-block-poly(methyl methacrylate) diblock copolymer in benzene, toluene, ethylbenzene,... 

Recently Lodge, Frisbie, and coworkers have used block copolymer-based ion gel to prepare flexible, low-voltage, emissive displays on plastic [133]. The patterned ion gels contain redox-active luminophores and triblock copolymer of polystyrene-block-poly(methyl methacrylate)-bloek-polystyrene, where the solvophotric poly styrene end blocks associate form micelles in l-ethyl-3-melhylimidazolium bis(trifluoromethylsulfonyl)imide [C2mim][N(T02l. 

The carbanion pump method has been successfully applied for the preparation of different block copolymers including poly(ethylene oxide)-block-polystyrene, poly(ethylene oxide)-block-polystyrene-block-poly(ethylene oxide), poly(ethylene oxide)-block-poly(methyl methacrylate), poly(ethylene oxide)-block-poly(methylmethacry-late)-block-poly(ethylene oxide) (shown in Scheme 14), and poly(ferrocenyldimethylsilane)-block-(methyl methacrylate) <2004MI856, 2004MM1720, 2006MI(928)292>. 

Krappe U, Stadler R et al (1995) Chiral assembly in amorphous ABC triblock copolymers. Formation of a helical morphology in polystyrene-block-polybutadiene-block-poly(methyl methacrylate) block copolymers. Macromolecules 28 4558 1561... 

First experiments which focused on the variation of the conformational properties have been performed by Brown et al. [240], who studied the role of the interactions between matrix and brush polymers (enthalpy driven brush swelling, see Eq. 59). They used a series of polystyrene (PS)-poly(methyl methacrylate) (PMMA) symmetric diblock copolymers with different blocks labeled by deuterium, placed at the interface between PMMA and poly(2,6-dimethylphenylene oxide) (PPO) homopolymers. A double brush layer was created with PMMA blocks dangling into (neutral) PMMA homopolymer and PS blocks immersed in favorably interacting PPO melt (x=Xps/ppo<0)- The SIMS profiles obtained showed that the PS side of the block copolymer is stretched by at least a factor of 2 with respect to the PMMA side. 

Several other diblock and triblock copolymers have been synthesised, although these are of limited commercial availability [7]. Typical examples are diblocks of polystyrene-block-PVA, triblocks of poly(methyl methacrylate)-block PEO-block poly(methyl methacrylate), diblocks of polystyrene block-PEO, andtriblocks of PEO-block polystyrene-PEO. An alternative - and perhaps more efficient - polymeric... 

Optical densities at 269.5 nm for polystyrene solutions at concentrations of 0-1 X 10"2 mole/liter and for poly(styrene-co-methyl methacrylate) solutions at a total concentration of 1 X 10 2 mole/liter are presented in Figure 1 as functions of styrene content. The solvents were (from the top) dioxane, chloroform, tetrahydrofuran (THF), tetrachloroethane (TCE), and dichloro-ethane (DCE). It is evident that the linear relationship between optical density and styrene concentration that is valid for a polystyrene at all concentrations (open circles) does not hold for the statistical copolymers (solid circles). For example, copolymer (25-80 mole % styrene) solutions in chloroform deviate markedly from linearity the maximum per cent decrease in extinction coefficient (hypochromism) corresponds to a copolymer containing 50 mole % styrene. We define hypochromism as the decrease in absorption intensity at 269.5 nm per chromophore of the statistical copolymer relative to that of the atactic polystyrene. It is also evident from Figure 1 that the alternating copolymer also gives a sharp hypochromism whereas block copolymers and mechanical mixtures of polystyrene and poly (methyl methacrylate) do not deviate from the straight line. Similar results were obtained with the other solvents, but the composition range where hypochromism appears depends on the solvent used. 

Stenert, M., Doring, A., and Bandermann, F. 2004. Poly(methyl methacrylate)-block-polystyrene and polystyrene-block-poly( -butyl acrylate) as compatibihzers in PMMA/PNBA blends, e-Poly-mers 15,1-16. 

Fig. 4.2 (a) Transmission electron micrograph of a polystyrene-block-poly(ethylene-co-butyl-ene)-block-poly(methyl methacrylate) (SEBM) triblock copolymer, stained with RUO4, presenting the morphology called the knitting pattern. Bar = 0.5 pm. (b) Schonatic description of the triblock chain conformation within the unit cell. Adapted with pmnission from ref. [32], Macromolecules 1998, 31, 135. Copyright 1998 American Chemical Society... 

Breiner, U., Krappe, U., Thomas, E.L., Stadler, R. Structural characterization of the knitting pattern in polystyrene-block-poly(ethylene-co-butylene)-block-poly(methyl methacrylate) triblock copolymers. Macromolecules 31, 135 (1998)... 

In addition to the microphase separation phenomenon, in the presence of an interface, the affinity of one of the blocks by the interface influences the flnal rearrangement of the block copolymer at the outmost surface as has been already reported, for instance by Coulon et al. [96] for the case of polystyrene-6-poly (methyl methacrylate) block copolymers (Fig. 5.12). Initially, upon spin coating the block copolymers are rather disordered due to the fast evaporation process. However, upon annealing reorganization occurs and nanometer scale phases rich in each of the components are observed. Finally, the difference in the surface energies of the components forces the orientation of these domains parallel to the surface, with the lower-surface-energy block located at the surface [96-98]. 

The second and most important criterion for effective steric stabilization is to ensure strong adsorption of the chain to the particle surface (a strong anchor to the surface is essential). This prevents any displacement of the chains on close approach of the particles. This is particularly the case with concentrated dispersions, whereby the particles approach each other to close distances of separation. In order to ensure a strong anchor to the surface, one uses block and graft copolymers (A-B, A-B-A and BA ). The chain B is chosen to be highly insoluble in the medium and should have strong affinity to the surface. Suitable examples of B chains for hydrophobic particles in aqueous media are polystyrene and poly(methyl methacrylate). 

In other applications, Baysal utilized methylene dicyclohexyl isocyanate to link polybutadiene with polystyrene or poly(methyl methacrylate) to form the appropriate block copolymers(70). Diphenyl methane-4,4 diisocyanate was similarly used to prepare a block... 

FIGURE 20 The LC LCD separation of polystyrene and poly(methyl methacrylate) homopolymers from the real sample of block copolymer PS-block-PMMA with help of LC LCD a) original chromatogram, b) sample spiked with PS, c) sample spiked with PMMA. The colunm packing was bare silica gel with pore size of 6 mn. Eluent was a mixture THF/toluene 70/30, barrier 1 was neat toluene, and barrier 2 was a mixture of THF with toluene 30/70. All mixed solvent compositions are in weight percent. 

The self-consistent field theory also allows one to calculate the segment density profiles of each homopol)maer and each block of the copolymer. Forward recoil spectrometry is unable to resolve the details of these concentration profiles — the apparent finite width of the copolymer layer shown in figure 6.6 is entirely due to the instrumental resolution - but from neutron reflectivity measurements on a series of differently labelled samples one is able to extract all four segment density profiles. Figure 6.20 shows an example of this, for a styrene/methyl methacrylate copolymer at an interface between polystyrene and poly(methyl methacrylate). 

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