Polyisoprene-polystyrene copolymers

Itarou H., Mays I.W., and Hadjichri-Stidis N., Regular comb polystyrene and graft polyisoprene/ polystyrene copolymers with double branches ( Centipedes ). Quality of (l,3-phenylene)bis(3-methyl-l-phenylpentylidene)dilithium initiator in the presence of polar additives. Macromolecules, 31,6697, 1998. 

FT IK-PAS can also be used as a rapid and nondestructive technique for quantitative characterization of the surface degradation of aged polymers and other compounds. Using FTIR-PAS spectroscopy, oxidation profiles of the various photooxidized polyisoprene-polystyrene copolymers have been investigated. 

LeiblerL., Theory of microphase separation in block copolymers. Macromolecules, 13, 1602, 1980. Eoerster S., Khandpur A.K., Zhao J., Bates E.S., Hamley I.W., Ryan A.J., and Bras W. Complex phase behavior of polyisoprene-polystyrene diblock copolymers near the order-disorder transition. Macromolecules, 21, 6922, 1994. 

Table 1 Composition and molecular weight of the studied polystyrene-WocC-polyisoprene (SI) copolymers...

Fig. 6. Examples of electron micrographs of the inverse centered cubic structure38). Copolymer polystyrene-polyisoprene-polystyrene SIS. 1107 containing 10% polystyrene. White circles are polystyrene spheres.

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. ... 

Khandpur AK, Forster S et al (1995) Polyisoprene-polystyrene diblock copolymer phase diagram near the order-disorder transition. Macromolecules 28 8796-8806... 

QuasicrystaUine phases form at compositions close to the related crystalline phases. When solidified, the resultant strucmre has icosahedra threaded by a network of wedge disclinations, having resisted reconstruction into crystalline units with three-dimensional translational periodicity. The most well-known examples of quasicrystals are inorganic phases from the ternary intermetallic systems Al-Li-Cu, Al-Pd-Mn, Zn-Mg-Ln, Al-Ni-Co, Al-Cu-Co, and Al-Mn-Pd. In 2007, certain blends of polyisoprene, polystyrene, and poly(2-vinylpyridine) were found to form star-shaped copolymers that assemble into the first known organic quasicrystals (Hayashida et al., 2007). 

Figure 13.15 Reduced storage modulus versus reduced frequency arco for a lamellae-forming polystyrene-polyisoprene diblock copolymer (M = 22,000) at temperatures above the order-disorder transition temperature Todt = 152°C, and quenched to temperatures below it. The disordered samples show terminal behavior, and the ordered (but unoriented) ones show nonterminal behavior. (Reprinted with permission from Patel et al.. Macromolecules 28 4313. Copyright 1995, American Chemical...

Figure 13.22 Damping functions hf y) and hs y) for the fast and slow relaxation processes of a 15 wt% solution of a micelle-forming polystyrene-polyisoprene diblock copolymer (molecular weights, respectively, of 14,000 and 29,000) in a low-molecular-weight (A/ = 4,000) polyisoprene. Damping functions for linear and star polymers and for silica dispersion are shown for comparison. (From Watanabe et al. 1997, with permission from Macromolecules 30 5905. Copyright 1997, American Chemical Society.)...

Kesselman, E., Talmon, Y., Bang, J. et al. (2005) Cryogenic transmission electron microscopy imaging of vesicles formed by a polystyrene-polyisoprene diblock copolymer. Macromolecules, 38 (16), 6779-6781. 

The ability of living polymers to resume growth with the addition of fresh monomer provides an excellent opportunity for the preparation of block copolymers. For example, if a living polymer with one active end from monomer A can initiate the polymerization of monomer B, then an A-AB-B type copolymer can be obtained (e.g., styrene-isoprene copolymer). If, however, both ends of polymer A are active, a copolymer of the type B-BA-AB-B results. Examples are the thermoplastic rubbers polysty-rene-polyisoprene-polystyrene and poly(ethylene oxide)-polystyrene-poly(ethylene oxide). In principle, for fixed amounts of two monomers that are capable of mutual formation of living polymers, a series of polymers with constant composition and molecular weight but of desired structural pattern can be produced by varying the fraction and order of addition of each monomer. 

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). 

Polymer (B) polystyrene-b-polyisoprene diblock copolymer 1997ZHA... 

It was reported recently, that polymeric can also form quasicrystals. Hayashida et al. [50] demonstrated that certain blends of polyisoprene, polystyrene, and poly(2-vinylpyridine) form starshaped copolymers that assemble into quaskrystals. By probing the samples with transmission electron microscopy and X-ray diffraction methods, they conclude that the films are composed of periodic patterns of triangles and squares that exhibit 12-fold symmetry. These are signs of quasicrystalline ordering. Such ordering differ from conventional crystals lack of periodic structures yet are well-ordered, as indicated by the sharp diffraction patterns they generate. Quasi-crystals also differ from ordinary crystals in another fundamental way. They exhibit rotational symmetries (often five or tenfold). There are still some basic questions about their stracture. 

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. 

Block copolymers are long-chain molecules composed of multiple blocks of distinct monomers (see Fig. 17). They are widely used as adhesives, and because they can reduce interfacial energy they can act as compatibilizers in polymer blends. In addition, many of the novel and fascinating properties of block copolymers arise from microphase separation. Thermoplastic elastomers, such as polyurethanes and polystyrene-polyisoprene-polystyrene triblock copolymers, act like cross-linked elastomers, although there is no true cross-linking. Instead, rubbery portions of the... 

Figure 13.14 Dynamic storage shear modulus as a function of temperature for a series of polyisoprene-polystyrene diblock copolymers. Open and filled arrows indicate order-order and order-disorder phase transitions, respectively. The y-axis data have been multiplied for clarity sample g has the actual values of G. Note that all samples are above the glass transition temperatures of both polymers, and hence In the melt state.

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