Polystyrene polyisoprene and

Several studies have been published which utilize size exclusion chromatography (SEC) for characterization of the molecular weight distribution of multi-arm structures of polystyrene, polyisoprene, and block copolymers of styrene/ butadiene and styrene/isoprene (1, 2, 8, 17, 25-26). An... 

The ability of Th-FFF to separate polymers by chemical composition [2] was demonstrated in the separation of polystyrene, polyisoprene and polybutadiene polymers of similar molecular weight [349] and extended to polytetrahydrofuran [350]. An impressive example of the ability to separate according to chemical composition was reported for two polymers indistinguishable by SEC (See Fig. 10). 

Levy and Schlick (9) applied this technique to the system polystyrene-polyisoprene and produced polymers containing 3, 5, 7, and 9 blocks respectively. 

Figure 8.12. The Debye-Bueche plots for ternary blends of polystyrene, polyisoprene, and styrene-isoprene block copolymers [Moritani et at, 1970],...

Steinhoff, B. Rullmann, M. Wenzel, M. Junker, M. Alig, I. Oser, R. Stuhn, B. Meier, G. Diat, O. Bosecke, P. Stanley, H. B. (1998) Pressure Dependence of the Order-to-Disorder Transition in Polystyrene/Polyisoprene and Polystyrene/Poly(methylphenylsiloxane) Diblock Copolymers, Macromoleculesy 31, 36-40. 

PA-polymethyl methacrylate graft copolymers were the products of the polymerization of methyl methacrylate on polyacetylene doped by Na [107]. Polystyrene, polyisoprene, and cis-1,4-polybutadiene were used as polymer carriers [108,109]. Acetylene was polymerized with Ti(OBu)4-AlEt3 in a toluene solution of the polymer carrier. The authors considered the formation of graft copolymers to be the result of the nucleophilic effect of a growing PA chain on the electrophilic sites in the polymer carrier. 

In addition, polymer micelles have been demonstrated to be more stable and also have a significantly lower cmc than surfactant micelles. Further discussion of surfactant micelles is beyond the scope of this review, and, instead, the reader is directed to a recent review article by Armes. In fact, the polymer building blocks need not be amphiphilic and such phase-separated nanostructures can be formed from completely hydrophobic or lipophilic diblock copolymers that contain two segments with differing solubility (such as polystyrene- -polyisoprene) and hence can undergo phase separation in selective solvents. One example of such completely hydrophobic phase-separated micelles are those reported by Wooley and coworkers, which can be obtained from toluene and acetone solutions of a [polystyrene-a/f-poly(maleic anhydride)]-fc-polyisoprene Iriblock. Conversely, inverse structures are also accessible and are known as reverse micelles. These can be formed by adding a nonsolvent for the hydrophilic block to afford the opposite of a conventional micelle, for which the hydrophilic core is surrounded by a hydrophobic shell in a hydrophobic surrounding media. There have been a handful of reports on the application of these reverse micelles, for example, as nanoreactors and for the extraction of water-soluble molecules. ... 

Gisser and Ediger(41) studied solvent and solute rotation with C and nuclear magnetic resonance. The selectivity of NMR allows separate measurement of reorientation times for multiple components of a mixture. Dilute polystyrene, polyisoprene, and polybutadiene were found to retard the rotational diffusion of the toluene solvent, polystyrene being modestly more effective as a retardant. Solvent Tr depends exponentially on polymer c, at least up to 90 g/1 of polymer. Gisser and Ediger also examined the small-molecule mixture chloronaphthalene ... 

Systems with UCST include polystyrene-poly(methyl methacrylate), and polystyrene-polyisoprene and LCST is found with poly(a-methyl styrene)-poly(methyl methacrylate), poly(styrene-co-acrylonitrile) (SAN)-polycaprolactone and poly(ethylene-co-vinyl acetate)-chlorinated polyethylene [ 5 ] as well as various polyvinylidene fluoride-polyacrylate copolymer blends [35]. 

A very interesting labeling to investigate dynamics of polymer chains is the main chain labeling. In the case of polymerizations, the best way, en it is possible, is to perform an anionic polymerization and to terminate the living chains with 9,10 bis bromomethyl anthracene (Fig. 6, scheme 1) (11). Polystyrene, polyisoprene and other polydienes... 

Figure C2.1.11. Morjrhologies of a microphase-separated di-block copolymer as function of tire volume fraction of one component. The values here refer to a polystyrene-polyisoprene di-block copolymer and ( )pg is tire volume fraction of the polystyrene blocks. OBDD denotes tire ordered bicontinuous double diamond stmcture. (Figure from [78], reprinted by pemrission of Annual Reviews.)...

Materials that are constructed from organic polymers such as polyethylene, polystyrene, polyisoprene (natural rubber and a synthetic elastomer) and poly(vinyl chloride) are common features of our daily lives. Most of these and related organic polymers are generated from acyclic precursors by free radical, anionic, cationic or organometallic polymerisation processes or by condensation reactions. Cyclic precursors are rarely used for the production of organic polymers. 

The values of Mc [defined by Eq.(5.19)] are those reported by Ferry (15) and Berry and Fox (16), except that for polystyrene (124) and the values in parentheses for poly-methyl methacrylate (146), polybutadiene (79,197), and ds-polyisoprene (79, 197). The values of (defined as described in 5.4.1) are from the same compilations, except that for poly (a-methyl styrene) (161). The values of Mc were obtained as described in Section 5.4.4. 

The living character of organolithium polymerizations makes such processes ideally suited for the preparation of pure as well as tapered-block copolymers. Diene-olefin pure-block copolymers have become important commodities because of their unique structure-property relationships. When such copolymers have an ABA or (AB) X [A = polyolefin, e.g., polystyrene or poly(a-methylstyrene) B = polydiene, e.g., polybutadiene or polyisoprene and X = coupling-agent residue] arrangement of the blocks, the copolymers have found use as thermoplastic elastomers (i.e., elastomers that can be processed as thermoplastics). 

In an investigation of the effect of chain geometry on the two phase morphology of polystyrene-polyisoprene block copolymers, Price et al. have studied films of AB linear, AB stars with 2,3 or 4 branches196,197), graft copolymers 198 200>, and ABC block terpolymers201. ... 

ABC copolymers polystyrene-polyisoprene-poly(vinyl-2-pyridine)(S.I.V2P) with number-molecular average weight of 23000,102000, and 23000 were prepared by stepwise anionic polymerization. Films obtained by solvent casting from methylcyclohexane and benzene were observed by electron microscopy after staining the polyisoprene block with osmium tetroxide or the poly(vinyl-2-pyridine)... 

Molded foam copolymers with 10-30% glycidyl acrylate may be crosslinked by heating in the presence of polyamines. Heat resistance may be increased to as high as 150°C. by this treatment (25). Use of certain allyl or diallyl esters to control the crosslinking of polystyrene to the desired very light extent has been disclosed as a means of obtaining foams of improved and regular cell structure (135). Block copolymers of polystyrene, polydiene (particularly polyisoprene), and polystyrene... 

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