Block polystyrene/polyisoprene

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.)...

Measurements of diffusion of tracer polymers in ordered block copolymer fluids is another potentially informative activity, since molecular diffusion is one of the most basic dynamic characteristics of a molecule. Balsara, et al. have measured the retardation of diffusion due to ordering in the diffusion of polystyrene tracer homopolymers in polystyrene-polyisoprene matrices of various domain sizes [167]. Measurement of the tracer diffusion of block copolymer molecules will also be important. Several interesting issues are directly addressable via measurements... 

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 purpose of this contribution is to show how the design of a new dianionic species can lead to interesting advances in block copolymerization and especially to original PA(P0)2 starshaped block copolymers. PA is a hydrophobic block polystyrene, polytertiarybutylstyrene (PTBS) or polyisoprene (Pi). The surface activity of this novel and well mastered molecular architecture is considered and compared as far as possible with the behavior of the corresponding PA-PO diblock copolymers. 

Balsara NP, Hammouda B (1994) Shear effects on solvated block-copolymer lamellae -polystyrene-polyisoprene in dioctyl phthalate. Phys Rev Lett 72(3) 360-363... 

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)... 

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. 

Thus a statistical copolymer of ethylene and propyiene is named poly(ethylene-stef-propylene), and an ABA tri-block copolymer of styrene (A) and isoprene (B) is named polystyrene-block-polyisoprene-block-polystyrene. In certain cases, additional square brackets are required. For example, an alternating, copolymer of styrene and maleic anhydride is named poly[styrene-d/f-(maleic anhydride)]. 

Figure 4.25. High magnification image.s obtained by transmission electron microscopy of stained thin sections of a hyperbolic mesopha.se of a linear diblock copolymer, polystyrene-polyisoprene, whose morphology follows the D-surface (single node circled in middle picture) and possibly the gyroid. Staining produces high contrast between the two block domains. Note the very different magnifications.

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

Fig-1- Variation of the apparent mean-square radius of gyration app (solid lines) and the apparent reciprocal hydrodynamic radius app (dotted lines) as a function of the solvent refractive index ns and refractive index increment dn/dc for a heterogeneous star mol ecule (AB)f with f= 18 block B, polyisoprene, M=230 000 block A, polystyrene, M=150 000... 

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

In order to improve the processing and end-user properties and also to simplify the preparation of the blends described above, we propose to design new copolymers which would have the same block sequences (polyisoprene and polystyrene) but not the same topology [23, 26-28]. We have already pointed out that, to obtain optimized rheological properties for a good tack, we must have a free polyisoprene sequence which explores the network of the trapped polyisoprene sequences of the triblock copolymer and swells this network. It is important to notice that this is the triblock copolymer which causes the soUd-Uke behavior [23]. This configuration can be obtained with a series of block sequences terminated by a polyisoprene sequence [26-28] ... 

Ren, J., SUva, A. S., and Krishnamoorti, R., Linear viscoelasticity of disordered polystyrene-polyisoprene block copolymer based layered-silicate nanocomposites. Macromolecules, 33, 3739-3746 (2000). 

H. Odani, M. Uchikura, Y. Ogino, M. Kurata, Diffusion and solution of methanol vapor in poly(2-vinylpyridine)-block-polyisoprene and poly(2-vinylpyridine)-block-polystyrene, J. Membr. ScL, 15, 193-208 (1983). 

Continuous measurement of viscosity. The accuracy of the Mark-Houwink equation will be improved if the intrinsic viscosity of a fraction at each retention volume can be measured continuously. An automatic viscometer having a capillary of 0.5 mm in diameter and a length of 200 mm was constructed and applied to the estimation of molecular mass of di- and triblock copolymers of polystyrene-polyisoprene P(S-IP) and di-block copolymer of P(S-MMA) [32]. In the case of copolymers which have homogeneous... 

Morris, M.A. Polymer nanostructures in sub-micron lithographically defined channels film-thickness effects on structural alignment of a small feature size polystyrene-polyisoprene-polystyrene block copolymer. Soft Matter. 2007, 2, 916-921. 

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