Polystyrene-polybutadiene diblock copolymer

Figure 14. Gel permeation chromatograms of polystyrene and polystyrene-polybutadiene diblock copolymer prepared with Ba-Mg-Al. Conditions solvent, cyclohexane 50° C.

Sehwier CE, Argon AS, Cohen RE. Crazing in polystyrene-polybutadiene diblock copolymers containing cylindrical polybutadiene domains. Polymer 1985 26(13) 1985—1993. 

Starting in the 1980 s, a number of governmental recycling policies created a demand for recycled thermoplastic olefin (TPO) for post-consumer applications. Since polystyrenes and TPOs are not miscible, polystyrene-TPO diblock copolymers are being developed to reduce the interfacial tension in PS/TPO blends. TPOs are tough materials with low stififiiess properties. If blended with polystyrene, they improve the toughness of polystyrenes. If compatibilized, the properties of PS/TPO should be similar to styrene-hydrogenated polybutadiene rubbers. 

As an example of blends with attractive interactions, Fig. 65 shows a superstructure in which interactions between methacrylic acid groups and pyridine side groups of a polystyrene-fc-polybutadiene-fo-poly(f-butyl methacry-late-staf-methacrylic acid) (PS-b-PB-b-P(MAA-sfaf-fBMA)) triblock quater-polymer and a PS- -P2VP diblock copolymer lead to a wavy lamellar structure with cylinders from mixed P2VP and P(MAA-sfaf-fBMA) blocks [194],... 

The most simple diblock copolymers are linear chains, in which one part of the chain consists of one type of monomer, say polystyrene (PS), and the other one of another type, say polybutadiene (PB), as illustrated in Figure 14. PS and PB usually phase separate at low temperatures however, because of their chemical connectivity, block copolymers cannot unmix on a macroscopic scale. They can only phase separate on a microscopic scale, the size of which is determined by the length of the polymers. 

The experimental studies on phase behavior and pattern formation reviewed here have been done on substrate-supported films of cylinder-forming polystyrene- foc -polybutadiene diblock (SB) [36, 43, 51, 111-114] and triblock (SBS) [49, 62, 115-117] copolymers (Table 1), lamella-forming polystyrene- /ocfc-poly(2-vinyl pyridine) diblock copolymers (SV) [118, 119] and ABC block terpolymers of various compositions [53, 63, 120-131], In simulation studies, a spring and bid model of ABA Gaussian chains has been used (see Sect. 2) [36,42, 58, 59],... 

The morphologies of polystyrene-F-polybutadiene (PS-F-PBD) diblock copolymers confined in a nanopore were observed by Shin and Xiang (Shin et al., 2004), in which a lot of attentions were paid to the layer number of the concentric cylinder barrel structure as a function of the nanopore radius. In this work, the symmetrical and asymmetrical... 

The comparison of BS and symmetric BSB copolymers derived from the BS polymer by addition of a B block identical to the first one has demonstrated that the addition of a third block to a diblock copolymer achieves a stretching of both the polybutadiene and the polystyrene chains92. ... 

The substantial work on polystyrene/polybutadiene and polystyrene/ polyisoprene blends and diblock and triblock copolymer systems has lead to a general understanding of the nature of phase separation in regular block copolymer systems (5,6). The additional complexities of multiblocks with variable block length as well as possible hard- and/or soft-phase crystallinity makes the morphological characterization of polyurethane systems a challenge. 

Figure 4.27 Traiumission electron micrographs of a mixture of a star diblock copolymer (polybutadiene-polystyrene) with a homopolymer (polystyrene). The upper EM images show mesh layers viewed end-on. The lower image shows the mesh sheets viewed from above, revealing the dense network of pores in the layers, so that the sheets are in fact a filigree of interconnected tunnels. The large-scale dark (one marked A) and bright (B) fringes are due to variations in the thickness of the specimen only. Pictures reproduced witti permission from [48].

The coordination of metals to various other pendant sites present in block co-polymers has also been explored. For example, metal coordination to the olefinic groups present in the polybutadiene (PB) blocks of polystyrene-/ -polybutadiene (PS-/ -PB) diblock and PS- -PB-3-PS triblock copolymers has been reported.This was achieved by the reaction of PS-/ -PB with various metal complexes such as Fe3(CO)i2, [Rh(/r-Cl)(CO)2]2, PdCl2(NCMe)2, and PtCl2(NCMe)2 to afford materials with Fe-, Rh-, Pd-, and Pt-containing blocks. Intermolecular cross-linking was possible but solubility in organic solvents was maintained and micellization was observed in most cases. However, on solvent removal and drying, many of the polymers became insoluble. 

ABB Abbas, B., Schwahn, D., and Willner, L., Phase behavior of the polybutadiene-polystyrene diblock copolymer with the addition of the nonselective solvent dichlorobenzene in temperature and pressure fields, J. Polym. Sci. Part B Polym. Phys., 42, 3179, 2004. 

Self-assembled block copolymers are basically amphilic molecules which contain distinctively different polymers. This block copolymer contains two or more polymers quantitatively in the form of blocks. Some of the block copolymers are polyacrylic acid, polymethylacrylate, polystyrene polyethylene oxide, polybutadiene, polybutylene oxide, poly-2-methyloxazoline, polydimethyl sUoxane, poly-e-caprolactone, polypropylene sulfide, poly-A -isopropylacrylamide, poly-2-vinylpyridine, poly-2-diethylamino ethyl methacrylate, poly-2-(diisopropylamino) ethyl methacrylate, poly-2-(methacryloyloxy) ethyl phosphorylcholine, and polylactic acid. These copolymers contain more than polymers to form certain configurations like linear, branched, patterned. For example, if we take three polymers named A, B, and C, they can be combined to form arrangements AB, BA, AA, BAB, ABCAB, ABCABC, ABABAB, etc. in the form of branched configuration it forms (ABQa, (ABA)a, (AB)4, etc. Depending on the above-mentioned number of blocks, they are named as AB diblock copolymers, ABC triblock copolymers, ABC star block copolymers, etc. The covalent linkage between these different blocks of polymers makes macroscopic phase separation impossible, that is, in its place the phase separation... 

Fig. 2, 20 TEM-pictures of multiphasic materials (a) Micromorphology of high impact polystyrene. White Polystyrene, black Polybutadiene (see Sect. 5.5.2.4). (b) Lamellar micromorphology of an AB diblock copolymer (see Sect. 3.4.2.1). (c) Quasi crystalline order of polystyrene particles in an artificial opal ...

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