PS-b-PMMA block copolymer

Fig. 7 2D thickness-surface energy gradient library for mapping the effects of these parameters on the self-assembly of PS-b-PMMA block copolymer thin films. See text for a fuU description. Lq is the equilibrium self-assembly period and h is the film thickness. Dashed white lines delineate the neutral surface energy region, which exhibits nanostructures oriented perpendicular to the substrate plane. (Derived from [18] with permission)... 

Stoykovich et al. ° formed nonregular patterns by combining ternary blends of PS-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymers and PMMA homopolymers on chemically nanopattemed substrates. The ternary... 

Fig. 17. (A) PS JT c=c image acquired at 285.3 eV from a 168-h annealed PS/PMMA/PS-6-PMMA microemulsion thin film washed with cyclohexane to remove all PS. At this photon energy, only the aromatic content of stjrrene will appear dark. Enhanced absorption, although at low contrast, can be detected at the domain interfaces that directly shows that the highest PS-6-PMMA block copolymer concentration is located at the PS/PMMA domain interface (B) The nexafs spectrum acquired from 10 area of this sample. The PS and PMMA intensities reveal that cyclohexane washing is removing essentially all PS. The remnant 285 eV signal is consistent with expected signal from the PS-6-PMMA block copolymer. (Data acquired with the Stony Brook STXM.)...

Walheim et al. reported PS droplets after annealing a 50/50 w/w PS/PMMA sample for 12 h at 190°C (Walheim et al. 1997), and Ade et al. have also found using scanning force microscopy surface phase-separated PS and PMMA domains with PS droplets after annealing at ISO C (Ade et al. 1999). Based on AFM microscopy investigations, Harris et al. showed that PS and PMMA are phase-separated on the surface only in PS-b-PMMA diblock copolymer films is the PS block always at the surface and the PMMA block never at the surface (Harris et al. 2003). 

The organization of PMMA-h-PS-b-PMMA triblock copolymers at the interface of immiscible homopolymers [87] was studied by dynamic secondary ion mass spectrometry. Selective labeling of either the two end blocks or the central block provided the contrast necessary to determine the spatial arrangements of the blocks at the interfaces. It was found that the triblock copolymer chains were organized such that the central block preferentially segregated to one homopolymer, whereas the end blocks segregated to the other, thus adopting a hairpin type of conformation as indicated in Fig. 19. 

Fig. 10 Schematic representation of the nanoreplication processes from block copolymers, a Growth of high-density nanowires from a nanoporous block copolymer thin film. An asymmetric PS-fc-PMMA diblock copolymer was aligned to form vertical PMMA cylinders under an electric field. After removal of the PMMA minor component, a nanoporous film is formed. By electrodeposition, an array of nanowires can be replicated in the porous template (adapted from [43]). b Hexagonally packed array of aluminum caps generated from rod-coil microporous structures. Deposition of aluminum was achieved on the photooxidized area of the rod-coil honeycomb structure (Taken from [35])...

Fig. 32. Maximum achievable fracture toughness of interfaces between A and B polymers reinforced with block copolymers or end-grafted chains as a function of the degree of polymerization N of the reinforcing block. (A) PS-b-PMMA between PPO and PMMA ( ) dPS-COOH chains in a HIPS matrix grafted on an epoxy interface ( ) dPS-COOH chains in a PS matrix grafted at an epoxy interface (O) PS-b-PVP chains at the interface between PS and PVP. Data from [22,36,38,40]...

Small angle X-ray scattering (SAXS) has been used by many authors to determine the interfacial thickness. An excellent review of this subject can be found in Perrin and Prud homme [1994]. Many methods of calculations can be used. One of these involves an analysis of the deviation from Porod s law, in which the desmearing procedure is avoided. This procedure was applied to blends of PS with PMMA added with a P(S-b-MMA) block copolymer. Upon addition of copolymer the interface thickness changed from A1 = 2 to 6 nm [Perrin and Prud homme, 1994]. 

Particle diameter versus annealing time at 180°C for (a) 70/30 polystyrene/polymethyl methacrylate (PS/PMMA) bend without addition of a copolymer and (b) 70/30 PS/PMMA blend with 5% PS-b-PMMA copolymer. (Reproduced from Macosko, C. W., Guegan, R, Khandpur, A. K., Nakayama, A., Marechal, P., and Inoue, T. 19%. Compatibitizers for melt blending Premade block copolymers. Macromolecules 29 5590-5598 with permission from American Chemical Society.)... 

Block copolymers have been used as a template for creating nanopartide patterns. For example, some applications such as catalysis and magnetic recording necessitate a surface presentation for the nanopartides. For this approach, it is critical that the block copolymers present multiple blocks at or near the free interface. PS-b-PMMA, which has both PS and PMMA domains displayed at the surface at appropriate surface thickness, is frequently utilized for this reason. Figure 3(c) illustrates the selective adsorption of Au onto the PS domains, forming arrays of nanoscale clusters and wires. ... 

Fig. 4.8 True color optical micrograph of a continuous 26k PS-b-PMMA film with thickness gradient. The lower section is a continuation of the upper section. Film was annealed for 6 h at 170 °C, and the image shows the addition of four successive lamellae to the block copolymer film with increasing thickness, and the corresponding terraced patterns. Labels indicate when the film thickness verifies hs = n+ ll2)do, where n = 2-6. Reprinted with permission from ref. [88], J. Polym. Sci. Part B Polym. Phys. 2001, 39, 2141. Copyright 2001 John Wiley and Sons...

Fig. 5.11 Schematics of thermodynamically stable diblock copolymer phases. The A-B diblock copolymer, such as the PS-b-PMMA molecule represented at the top, is depicted as a simple two-color chain for simplicity. The chains self-organize such that contact between the immiscible blocks is minimized, with the structure determined primarily by the relative lengths of the two polymer blocks ( ). Reproduced with permission from ref [95]...

More recently, the same group proposed a new methodology for the synthesis of exact graft copolymers composed of PMMA and five PS branches [231]. For this synthesis, a specially designed hving AB diblock copolymer (PS-b-PMMA), in-chain-functionahzed with a 3-tert-butyldimethylsilyloxymethylphenyl (SiOMP) group, is used as the building block unit (Scheme 5.23). In this case, three reaction steps are employed in an iterative synthetic sequence ... 

FIGURE 25 Comparison of SEC, LC LCD and 2D-LC real chromatograms of a typical commercial block copolymer PS-b-PMMA that contained parent homopolymers. For detailed explanation, see the text. 

There is current interest in the use of block copolymers to help create structures that have potential sensor applications, e.g. block copolymers of poly styrene-poly (methyl methacrylate) (PS-b-PMMA). The nature of the organization that is created in thin films is influenced by the factors influencing phase separation of the polymers and very importantly the surface energy of the substrate on which they are deposited (Figure 8.14). If a substrate is patterned and then certain areas chemically modified, a substrate is created with variation in the surface energy across the surface. This is discussed in more detail in Chapter 9. The differences in surface energy will influence the morphology created. 

FIGURE 28 Transmission electron micrographs of microtome slices of an aligned PS-PMMA block copolymer sample. In (a), the slice plane was perpendicular to the electric field direction, and in (b) and (c) the slice plane contained the electric field direction. Intersection of the slice plane with +1/2 and -1/2 disclination lines and wall defects (denoted with a w ) are indicated in (a). (Reprinted with permission from Ref. 65.)... 

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