Isoprene styrene block polymers

Gaseous CSI treated styrene - isoprene-styrene block polymer. 

FIGURE 22.5 OTHdC study on the temperature range of the dissociation of the micelle of a styrene-isoprene two-block polymer in n-decane. Column 3.70 fim x 300 cm. (Reprinted with permission from Ref. 14. Copyright 1989 American Chemical Society.)... 

Chlorosulfonated styrene resins and carboxyaminoacid polymers were also found to possess thromboresistant properties by Josefonwicz and coworkers [483]. Studies included investigation of the effect of spacer length between amine and carboxylic groups as well as modification of styrene/isoprene/styrene blocks with chlorosulfonyl isocyanate giving sulfamate and carboxylic functionality [484],... 

A asymmetric membrane prepared from styrene isoprene - styrene block co-polymer... 

Krameria argentea extract Krameria extract Krameria triandra extract. See Rhatany extract Kraton D 1101] Kraton D 1102. See Styrene/butadiene/styrene block copolymer Kraton D 1107] Kraton D 1107P] Kraton D 1111] Kraton D 1112P. See Styrene/isoprene/styrene block copolymer Kraton D 1116. See Styrene/butadiene polymer... 

Studies of polymers dissolved in various oils indicate general agreement, with the volume fraction exponent reported to be 2 to 2.3 (5,6). In a recent study, W.W. Graessley and co-workers (7) reported exponents of 2.22 and 2.26 for polybutadiene and hydrogenated polybutadiene in various diluents. G. Kraus and K.W. Rollmann (8) reported on the only study of resins as the polymer diluent. Using a styrene-isoprene-styrene block copolymer, they found exponents of 2.28 for the glycerin ester of stabilized rosin and 2.62 for a C -stream resin. Plateau modulus was identified as G in the rubbery plateau where tan 6 was a minimum in a temperature scan of the systems. 

Triblock polymers and radial block polymers of styrene and butadiene (or isoprene) are successful commercial thermoplastic elastomers pioneered by the Shell Chemical Company and the Phillips Petroleum Company. The low diene and high styrene block polymers are clear impact resisting plastics marketed by the Phillips Petroleum Company under the trade name K-Resins. One common deficiency of these polymers is the relatively low glass temperature (Tg) of the polystyrene end blocks. For the thermoplastic elastomers the service temperatures are limited to below 65°C. The Vicat softening... 

Shenoy, A.V. and Saini, D.R. (1986) Quantitative estimation of matrix filler interactions in ferrite-filled styrene-isoprene-styrene block copol3mer systems, Polym. Composites, 7,96-100. 

Other interesting blends containing PE are natural rubber/PE, PP/UHMWPE, polyvinylidene fluoride (PVDE)/UHMWPE, PE/EVA, PE/PVC, PE/liquid crystalline polymer (Vectra), and styrene-isoprene-styrene block copolymers with ULDPE [12] with good puncture resistance (>100 kN/m). 

Styrenic block copolymers (SBCs) are also widely used in HMA and PSA appHcations. Most hot melt appHed pressure sensitive adhesives are based on triblock copolymers consisting of SIS or SBS combinations (S = styrene, I = isoprene B = butadiene). Pressure sensitive adhesives typically employ low styrene, high molecular weight SIS polymers while hot melt adhesives usually use higher styrene, lower molecular weight SBCs. Resins compatible with the mid-block of an SBC improves tack properties those compatible with the end blocks control melt viscosity and temperature performance. 

Block copolymer chemistry and architecture is well described in polymer textbooks and monographs [40]. The block copolymers of PSA interest consist of anionically polymerized styrene-isoprene or styrene-butadiene diblocks usually terminating with a second styrene block to form an SIS or SBS triblock, or terminating at a central nucleus to form a radial or star polymer (SI) . Representative structures are shown in Fig. 5. For most PSA formulations the softer SIS is preferred over SBS. In many respects, SIS may be treated as a thermoplastic, thermoprocessible natural rubber with a somewhat higher modulus due to filler effect of the polystyrene fraction. Two longer reviews [41,42] of styrenic block copolymer PSAs have been published. 

Short fiber reinforcement of TPEs has recently opened up a new era in the field of polymer technology. Vajrasthira et al. [22] studied the fiber-matrix interactions in short aramid fiber-reinforced thermoplastic polyurethane (TPU) composites. Campbell and Goettler [23] reported the reinforcement of TPE matrix by Santoweb fibers, whereas Akhtar et al. [24] reported the reinforcement of a TPE matrix by short silk fiber. The reinforcement of thermoplastic co-polyester and TPU by short aramid fiber was reported by Watson and Prances [25]. Roy and coworkers [26-28] studied the rheological, hysteresis, mechanical, and dynamic mechanical behavior of short carbon fiber-filled styrene-isoprene-styrene (SIS) block copolymers and TPEs derived from NR and high-density polyethylene (HOPE) blends. 

This field is still active today numerous recent patents [46, 63-89] and several reports [90-92] have detailed the efficiency of such types of systems for the hydrogenation of unsaturated polymers resulting from the polymerization of dienes (butadiene, isoprene, 1,3-cyclohexadiene) or the co-polymerization of dienes and styrenes (block co-polymers of butadiene and styrene SB, SBS, SBSB polymers). 

Now again, a state of inhomogeneity in polymers, so especially interesting in films and interfaces, occur when discontinuities are built into the main valence chains and networks. Block polymers are the classic embodiments of this. Many periodic distances separating domains in such alternating or rhymthic copolymers have been reported. These indicate existence of phases in laminar domains and, in other cases, of spherical domains.(51) Cases are shown experimentally for styrene/isoprene copolymers and also for styrene/butadiene.(52,53,54)... 

Based on this approach Schouten et al. [254] attached a silane-functionalized styrene derivative (4-trichlorosilylstyrene) on colloidal silica as well as on flat glass substrates and silicon wafers and added a five-fold excess BuLi to create the active surface sites for LASIP in toluene as the solvent. With THF as the reaction medium, the BuLi was found to react not only with the vinyl groups of the styrene derivative but also with the siloxane groups of the substrate. It was found that even under optimized reaction conditions, LASIP from silica and especially from flat surfaces could not be performed in a reproducible manner. Free silanol groups at the surface as well as the ever-present impurities adsorbed on silica, impaired the anionic polymerization. However, living anionic polymerization behavior was found and the polymer load increased linearly with the polymerization time. Polystyrene homopolymer brushes as well as block copolymers of poly(styrene-f)lock-MMA) and poly(styrene-block-isoprene) could be prepared. 

Thus, the synthesis of a styrene-methyl methacrylate block polymer requires that styrene be the first monomer. Further, it is useful to decrease the nucleophilicity of polystyryl carbanions by adding a small amount of 1,1-diphenylethene to minimize attack at the ester function of MMA [Quirk et al., 2000]. Block copolymers of styrene with isoprene or 1,3-butadiene require no specific sequencing since crossover occurs either way. Block copolymers of MMA with isoprene or 1,3-butadiene require that the diene be the first monomer. The length of each segment in a block copolymer is controlled by the ratio of each monomer to initiator. The properties of the block copolymer vary with the block lengths of the different monomers. 

Figure 7. Physical properties of styrene-isoprene block polymers.

Almost all isoprene produced is used in the preparation of polymers and copolymers. cis-Polyisoprene, primarily for vehicle tyres, is the largest application, with styrene-isoprene-styrene (SIS) block polymers being a rapidly growing secondary application. Butyl rubber is a significant third application. World demand for isoprene for monomer use in 1992 was (thousand tonnes) polyisoprene, 827 SIS, 95 butyl rubber, 25 and other uses, 10 (Weitz Loser, 1989 Lybarger, 1995). 

Styrene-1,3-butadiene-styrene (SBS) or styrene-isoprene-styrene (SIS) triblock copolymers are manufactured by a three-stage sequential polymerization. One possible way of the synthesis is to start with the polymerization of styrene. Since all polystyrene chains have an active anionic chain end, adding butadiene to this reaction mixture resumes polymerization, leading to the formation of a polybutadiene block. The third block is formed after the addition of styrene again. The polymer thus produced contains glassy (or crystalline) polystyrene domains dispersed in a matrix of rubbery polybutadiene.120,481,486... 

Korotkov, A. A., L. A. Shibaev, L. M. Pyrkov, V. G. Aldoshin and S. Ya. Frenkel The synthesis and investigation of hybrid polymers. I. Styrene and isoprene block polymers formed by the catalytic polymerization in solution under the action of butyllithium. Vysokomolekulyarnye Soedineniya 1, 433... 

Levy, M., and S. Schlick Block-polymers of styrene and isoprene with variable distribution of monomers along the chain. J. Phys. Chem. 64, 883 (1960). 

Miyaki and Fujimoto and co-workers [16,17] have obtained an even finer distribution of fixed charge groups by casting films from multicomponent block copolymers such as poly(isoprene- >-styrene- >-butadiene- >-(4-vinyl benzyl)dime-thylamine- Msoprene). These films show a very regular domain structure with a 200-500 A spacing. After casting the polymer film, the (4-vinyl benzyl) dimethy-lamine blocks were quatemarized with methyl iodide vapor, and the styrene blocks were sulfonated with chlorosulfuric acid. 

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