Isoprene block copolymer with styrene

Block copolymers with styrene and tert-butyl acrylate were also successfully prepared. Germack and Wooley also reported the RAFT polymerization of isoprene using S-l-dodecyl-S -(r,r -dimethyl-r"-acetic acid)trithiocarbonate as the CTA with various initiators (Germack and Wooley, 2007). Polyisoprenes with relatively narrow molecular weight distributions 1.2-1.3)... 

Polymer modified asphalt originated in Europe in the early 1960s. Atactic PP is still used today in asphalt compositions mainly in Europe, Mexico and Asia. A PP copolymer containing 2-10% ethylene is more popular in USA. Thermoplastic block copolymers with styrene end blocks or with a diene midblock like S-B-S and styrene-isoprene-styrene (SIS) and their hydrogenated versions are common modifiers for asphalt [40]. 

Figure 2. Segmental density distribution of block copolymers with styrene-isoprene copolymer random and tapered terminal blocks segments. The upper figure is for a random styrene-isoprene copolymer end-block with uniform composition. The lower figure is that of a severely tapered copolymer end block. The A domain is viewed as equivalent to a block copolymer which is itself microphase-separated with its own interphase region. 

FIGURE 11.7 Polymer-analogous reactions to create semifluorinated polymers (a) hydrosi-lylation of polyhydrosiloxanes (b) conversion of hydroborated poly(styrene-Z -isoprene) block copolymers with 5/carboxylic acid chlorides. 

Fig. 10.9 Reflectance (blue) and transmission (yellow) measurements of poly(styrene-b-isoprene) block copolymer with molecular weights as shown...

Hayakawa, T., Wang, J., Xiang, M. et al. (2000) Effect of changing molecular end groups on surface properties synthesis and characterization of poly(styrene-fo-semifluorinated isoprene) block copolymers with -CF2H end groups. Macromolecules, 33,8012-8019. 

The XIV system seems unique among transition metal complexes in its ability to control the polymerization of a diene monomer, isoprene. A linear dependence of on conversion, first-order kinetics and moderate polydispersities (1.4-1.6) up to high conversion (>50%) were observed for epoxide/Cp2Ti Cl2/Zn=l/3/6-l/4/8 at 90-110 °C. Random and block copolymers with styrene could also be obtained. 

The poly(styrene-b-isoprene) (P(S-b-IP)) and poly(-styrene-b-2-vinyl pyridine) (P(S-b-2VP)) block copolymers with narrow molecular weight distributions for blending with the microspheres were also synthesized using the additional anionic polymerization technique. The number-average molecular weights (Mns) and PS contents are also shown in Table 1. 

Currently, important TPE s include blends of semicrystalline thermoplastic polyolefins such as propylene copolymers, with ethylene-propylene terepolymer elastomer. Block copolymers of styrene with other monomers such as butadiene, isoprene, and ethylene or ethylene/propy-lene are the most widely used TPE s. Styrene-butadiene-styrene (SBS) accounted for 70% of global styrene block copolymers (SBC). Currently, global capacity of SBC is approximately 1.1 million tons. Polyurethane thermoplastic elastomers are relatively more expensive then other TPE s. However, they are noted for their flexibility, strength, toughness, and abrasion and chemical resistance. Blends of polyvinyl chloride with elastomers such as butyl are widely used in Japan. ... 

The effect of blending LDPE with EVA or a styrene-isoprene block copolymer was investigated (178). The properties (thermal expansion coefficient. Young s modulus, thermal conductivity) of the foamed blends usually lie between the limits of the foamed constituents, although the relationship between property and blend content is not always linear. The reasons must he in the microstructure most polymer pairs are immiscible, but some such as PS/polyphenylene oxide (PPO) are miscible. Eor the immiscible blends, the majority phase tends to be continuous, but the form of the minor phase can vary. Blends of EVA and metallocene catalysed ethylene-octene copolymer have different morphologies depending on the EVA content (5). With 25% EVA, the EVA phase appears as fine spherical inclusions in the LDPE matrix. The results of these experiments on polymer films will apply to foams made from the same polymers. 

Quintac Linear styrene block copolymer with isoprene Nippon Zeon... 

Silicon-coated fiberglass Polysulfone resins Linear styrene block copolymers with butadiene/isoprene PP fibers... 

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. 

Ober and coworkers117 have grafted siloxanes onto a styrene-isoprene block copolymer via hydrosilylation of the pendant vinyl groups of the diene block with pentamethyldis-iloxane (30) (equation 12). 

Among copolymers containing isoprene, AB and ABA block copolymers of styrene and isoprene have been the most studied, but interesting results have also been obtained with copolymers of isoprene and vinylpyridine and of isoprene and methyl methacrylate. 

In the case of block copolymers from styrene and isoprene, it is not necessary to review separately the results obtained with bi an triblock copolymers for the following reasons first, the relations between the morphology and the mechanical properties of SIS copolymers have not been studied as extensively as those of SBS copolymers and the results obtained are similar, second, morphological studies have been performed by the same authors on both SI and SIS copolymers. 

Kawai and collaborators have extensively studied copolymers of styrene and isoprene. They have synthetized and studied SI copolymers63,169, SIS copolymers64, and ternary polymer blends of SI block copolymers with polystyrene and polyisoprene170-171 and proposed a thermodynamic interpretation of the domain structure in solvent-cast films of SI, SIS, and blends of these copolymers with their homopoly-mers63 64,172. ... 

A nine armed star block copolymer of styrene and isoprene with a polystyrene content of 27% has been prepared by Fetters204 via a two-stage anionic polymerization using m-divinylbenzene as coupling agent and studied by electron microscopy. Spheres of polystyrene arranged in a body centered cubic lattice have been claimed for this copolymer204. ... 

Styrene-Diene. These ( styrenic ) thermoplastic elastomers are block copolymers of styrene with butadiene (SBS) or isoprene (SIS) in about 30/70 monomer ratio. 

An other interesting example of copolymer is given by Georges et al. [52,59] who first demonstrated the living character of the polymerization of styrene initiated by dibenzoyl peroxide in the presence of Tempo or Proxyl (2,2,5,5-tetramethyl-l-pyrrolydinyloxy). Polystyrene with a narrow polydispersity (Mw/Mn = 1.2) is obtained and block copolymers with butadiene, isoprene, acrylate and methacrylate sequences are prepared ... 

Considerable efforts have been directed, primarily in Kennedy s group [3], to synthesize a series of block copolymers of isobutene with isoprene [90,91], styrene derivatives [92-104], and vinyl ethers [105-107]. Figure 7 lists the monomers that have been used for the block copolymerizations with isobutene. The reported examples include not only AB- but also ABA- and triarmed block copolymers, depending on the functionality of the initiators (see Chapter 4, Section V.B, Table 3). Obviously, the copolymers with styrene derivatives, particularly ABA versions, are mostly intended to combine the rubbery polyisobutene-centered segments with glassy styrenic side segments in attempts to prepare novel thermoplastic elastomers. These styrene monomers are styrene, p-methylstyrene, p-chlorostyrene, a-methylstyrene, and indene. 

The effect of surface constraints on the morphology of the star-block copolymers was studied by Thomas and coworkers [337]. Thin film droplets of samples with various functionalities were studied, and the ones that exhibited the OBDD structure in the bulk were found to be cylinders in this case. In an independent study, the lamellar domain spacings of 4-arm and 12-arm star-block copolymers of styrene and isoprene were found, by TEM and SAXS, to be the same as those of the arm material [338]. 

---