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Morphologies in Block Copolymers

Abstract

Block copolymers are polymers, inwhich different homo- or random copolymer segments are connected into one macromolecule. Block copolymers not only combine the properties of the constituting blocks, but may display new properties depending on the way the different blocks are combined into one macromolecule, the strength of incompatibility between different blocks, and their respective molecular weights. For the synthesis of block copolymers the reader is referred to Chapter 7. Besides their use as compatibilizers in polymer blends [1, 2], block copolymers have also a wide range of other potentials. Examples are their use as surfactants [3–5], light-emitting [6] or photovoltaic devices [7], or photonic crystals on optical length scales [8, 9]. Block copolymers have been also used as templates for ceramic structures [10, 11] and as hosts for colloidal metals [12] and transition metal complexes [13, 14]. The formation of vesicular structures in solution makes block copolymers also interesting as carriers of drugs or for cosmetic applications [15]. Thermoplastic elastomers based on hard and soft blocks are prominent examples, where block copolymers also received importance as bulk materials [16]. Among multiblock copolymers with hard and soft segments, polycondensates like polyesters-urethanes, polyether-urethanes, or polyester-amides should be mentioned. Also thermoplastic elastomers based on poly(butylene terephthalate) as hard segments and poly(ethylene oxide)-b-poly(ethylene-cobutylene)- b-poly(ethylene oxide) triblock copolymers as soft segments have been reported [17]. In this chapter we want to consider three different scenarios for this self-assembly of block copolymers: (i) morphology in the bulk, (ii) morphology under confinements, i.e., in thin films, and (iii) morphology in solution.
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