Copolymers topology

Figure 2 Schematic representation of linear multiblock copolymer topologies.

The most important benefit of living polymerizations is that they allow preparation of new macromolecules with precisely designed and controlled compositions (homopolymers, random, periodic, block, graft, and gradient copolymers), topologies (linear, star, comb, (hyper )branched, networks, etc), and fimctionalities placed at different parts of macromolecules or various combinations of these. Some of the possibilities are outlined below (244,245). 

The blocks of each of the polymers may be comprised of (1) homopolymer blocks, (2) statistical polymer blocks, (3) random copolymer blocks, (4) tapered copolymer blocks, (5) gradient copolymer blocks, and (6) other forms of block copolymers. Any copolymer topology that allows immiscible segments present in the system to phase separate inherently or upon annealing, either alone or in the presence of a solvent, is a snitable precursor material. 

Schappacher, M., Putaux, J.L., Lefebvre, C., and Deffieux, A. (2005b) Molecular containers based on amphiphiUc PS-h-PMVE dendrigraft copolymers Topology, organization, and aqueous solution jaoperties. Journal of the... 

The simplest, from the viewpoint of topological structure, are the linear polymers. Depending on the number m of the types of monomeric units they differentiate homopolymers (m=1) and copolymers (m>2). In the most trivial case molecules in a homopolymer are merely identified by the number l of monomeric units involved, whereas the composition of a copolymer macromolecule is defined by vector 1 with components equal to the numbers of mono-... 

Abstract This chapter gives an overview of the research on the self-assembly of amorphous block copolymers at different levels of hierarchy. Besides the influence of composition and topology on the morphologies of block copolymers with linear, cyclic and branched topologies blends of block copolymers with low molecular weight components, other polymers or block copolymers and nanoparticles will also be presented. 

The term star-block copolymer is used for a star architecture in which each arm is a diblock. The influence of chain topology on mechanical and morphological properties was investigated for copolymers composed of PS and PB with a constant styrene content of = 0.74 by Michler s group (Fig. 32) [101,102], While hexagonally packed cylinders of PB in a PS matrix were observed in a symmetric PS-fo-PB-fr-PS triblock copolymer, an L phase... 

In what follows we will discuss systems with internal surfaces, ordered surfaces, topological transformations, and dynamical scaling. In Section II we shall show specific examples of mesoscopic systems with special attention devoted to the surfaces in the system—that is, periodic surfaces in surfactant systems, periodic surfaces in diblock copolymers, bicontinuous disordered interfaces in spinodally decomposing blends, ordered charge density wave patterns in electron liquids, and dissipative structures in reaction-diffusion systems. In Section III we will present the detailed theory of morphological measures the Euler characteristic, the Gaussian and mean curvatures, and so on. In fact, Sections II and III can be read independently because Section II shows specific models while Section III is devoted to the numerical and analytical computations of the surface characteristics. In a sense, Section III is robust that is, the methods presented in Section III apply to a variety of systems, not only the systems shown as examples in Section II. Brief conclusions are presented in Section IV. 

Even though the works of Bailey et al. [120,127] and Epps et al. [121] present very comprehensive studies about the variation of the morphology as a function of composition and topology, they did not study in detail the relationship microphase separation-crystallization . Several contributions have been made in this area, when the triblock copolymers have only one crystal-lizable block [101,118,119,122,126,128-130]. Some relevant aspects of these references have already been mentioned. 

The discovery of new controlled polymerization techniques in the mid-1990s and the progress achieved in living polymerization toward well-defined block copolymers with complex topologies have certainly played a key role in the development of block copolymer micelles. 

The combination of oligo- or polysaccharides with non-natural polymeric structures opens up a novel class of materials. By varying the chain topology of the individual blocks as well as of the whole copolymer, the type of blocks, the composition etc., a complete set with tailor-made properties can be designed. 

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