Block copolymers polymer blends

Block copolymers, polymer blends, polymers at interfaces, liquid crystalline polymers, polymers with novel optical and electronic properties, cross-linked polymers (including elastomers and thermosets), and biocompatible polymers are all areas of active research that are beyond the scope of this chapter. 

Block copolymer/polymer blend PEG [31] Block copolymer PEG [82]... 

Block copolymer PCL [116] Block copolymer/polymer blend PE [131]... 

Microdomains of block copolymer/ homopolymer blends 25-A-diameter Pd clusters Metal-ion precursors, introduced into cast thin films of polymer microdomains, are reduced by high pressure hydrogen 60,61... 

Solubility in Methylene Chloride. The methods described above can show the presence of blocks of DMP and blocks of DPP units, but they do not distinguish between block copolymers and blends of homopolymers. Gel permeation chromatograms of the copolymers are sharp and symmetrical, indicating that they are indeed copolymers rather than blends, but this alone is not conclusive as blends of the homopolymers do not produce binodal or badly skewed curves under the conditions used unless the two polymers differ considerably in molecular weight. A partial answer to this question is provided by the solubility behavior in methylene chloride. Dimethylphenol homopolymer dissolves readily in methylene chloride but precipitates quantitatively on standing for a short... 

Knaub P, Camberlin Y (1988) Gerard JF, New reactive polymer blends based on poly(urethane ureas) (PUR) and polydisperse poly(dimethylsiloxane) (PDMS) control of morphology using a PUR-b-PDMS block copolymer. Polymer 29(8) 1365-1377... 

When a block copolymer is blended with the homopolymer of one of the monomers of which it is composed, the homopolymer will enter the block polymer domain structure only when its molecular weight does not greatly exceed that of the block sequences of like composition (1,2). When it does so, the homopolymer forms its own, usually much larger, domains which may absorb some of the like-block sequences in their surface regions. 

When a block copolymer is blended with a homopolymer that differs in composition from either block the usual result is a three-phase structure. Miscibility of the various components is not necessarily desirable. Thus styrene-butadiene-styrene block copolymers are recommended for blending with high density polyethylene to produce mixtures that combine the relative high melting behavior of the polyolefin with the good low temperature properties of the elastomeric midsections of the block polymers. 

The major cunent applications of block copolymers in blends involve styrene-diene polymers, but other block polymers are also useful. Siloxane-alkylene ether block copolymers are widely used as surfactants in the manufacture of polyurethane foams, for example. 

Small-angle X-ray scattering techniques provide a route to information at a larger scale, particularly in multi-phase materials such as semi-crystalline polymers, block copolymers, and blends. Quantitative details on crystalline lamellar size or on preferred orientation are just two examples of the structural parameters which can be obtained using this powerful technique.2" 2>243... 

Thermoplastic elastomers contain sequences of hard and soft repeating units in the polymer chain. Elastic recovery occurs when the hard segments act to pull back the more soft and rubbery segments. Cross-linking is not required. The six generic classes of TPEs are, in order of increasing cost and performance, styrene block copolymers, polyolefin blends, elastomeric alloys, thermoplastic urethanes, thermoplastic copolyesters, and thermoplastic polyamides. 

An elastomer which upon heating turns into regularly behaving linear polymer. Polystyrene-polybutadiene block copolymers, polypropylene blends with ethylene-propylene-diene terpolymer provide examples. 

Albalak, R. J., and Thomas, E. L., Roll-casting of block copolymers and of block copolymer-homopolymer blends, J. Polym. Sci. B Polym. Phys., 32, 341-350 (1994). 

The polyolefin block copolymers are lower in cost. Their suggested applications (74) include wire and cable insulation, replacements for PVC and styrenic block copolymers, and blends with polypropylene, either to improve impact resistance or as the soft phase in a hard polymer/elastomer combination. Processing conditions are similar to those for polyethylene, and thermal stability is excellent. 

The precursor polymer blend can be made out of (1) linear block copolymers, (2) AB block copolymers, (3) ABA block copolymers, (4) ABC block copolymers, (5) multiblock copolymers, (6) symmetrical and asymmetrical star block copolymers, (7) blends of polymers, (8) graft copolymers, (9) multibranched copolymers, (10) hyperbranched or dendritic block copolymers, and (11) novel brush copolymers. 

Abstract Smart polymers based on photoresponsive azobenzene moieties have been extensively explored as potential materials for high capacity optical storage. This chapter reviews different strategies to incorporate azobenzenes into polymeric structures as well as their photoresponse properties. The potential of this type of materials as volume holographic media is summarized with special emphasis on block copolymers and blends. Although side-chain azopolymers has been the most investigated, new macromolecular architectures have been recently proposed and will be briefly presented. 

Berges, C., Gimeno, N., Oriol, L., Pinol, M., Forcdn, E, Sanchez, C. and Alcala, R. (2012a) Photoinduced optical anisotropy in azobenzene containing block copolymer-homopolymer blends. Influence of mrcrostructure and molecular weight , Eur. Polym. J., 48, 613. 

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