Polyethylene-£>-poly diblock copolymers

Loo et al. [21,42,44,91] reported a simple exponential decay (n = 1) for polyethylene-fc-poly(styrene-ran-ethylene-ran-butene) [PE-fo-poly(SEB)] diblock copolymers in which the PE blocks form isolated spheres or cylin-... 

A diblock copolymer consisting of a block of polyethylene grafted with poly(vinyl chloride) and a block of polystyrene, the structure of which is ... 

Block copolymers can be produced from terminally borane-containing polyolefins. These borane-containing POs can be synthesized by the metallocene-catalyzed (co)polymerization of olefin(s) monomer with 9-BBN as a chain transfer agent or by the metallocene catalyzed copolymerization of olefins with allyl-9-BBN [55,56], as referred to above. Alternatively, borane-containing POs were prepared by hydroboration of terminally unsaturated PO, for instance, terminally vinyl PE and terminally vinylidene PP [33-35,57]. Such method could produce diblock copolymers, such as polyethylene-block-poly(methyl methacrylate) (PE-fo-PMMA), polypropylene-foZock-poly(methyl methacrylate) (PP-fc-PMMA), polypropylene-foZock-poly(butyl methacrylate) (PP-fc-PBMA), and PP-fc-PS. 

Zhang X, Burt HM. Diblock copolymers of poly(dl-lactide-block-methoxy polyethylene glycol) as micellar carriers of taxol. Pharm Res 1995 12 S-265. 

Self-assembled block copolymers are basically amphilic molecules which contain distinctively different polymers. This block copolymer contains two or more polymers quantitatively in the form of blocks. Some of the block copolymers are polyacrylic acid, polymethylacrylate, polystyrene polyethylene oxide, polybutadiene, polybutylene oxide, poly-2-methyloxazoline, polydimethyl sUoxane, poly-e-caprolactone, polypropylene sulfide, poly-A -isopropylacrylamide, poly-2-vinylpyridine, poly-2-diethylamino ethyl methacrylate, poly-2-(diisopropylamino) ethyl methacrylate, poly-2-(methacryloyloxy) ethyl phosphorylcholine, and polylactic acid. These copolymers contain more than polymers to form certain configurations like linear, branched, patterned. For example, if we take three polymers named A, B, and C, they can be combined to form arrangements AB, BA, AA, BAB, ABCAB, ABCABC, ABABAB, etc. in the form of branched configuration it forms (ABQa, (ABA)a, (AB)4, etc. Depending on the above-mentioned number of blocks, they are named as AB diblock copolymers, ABC triblock copolymers, ABC star block copolymers, etc. The covalent linkage between these different blocks of polymers makes macroscopic phase separation impossible, that is, in its place the phase separation... 

Sun L, Liu YX, Zhu L, Hsiao BS, AvUa-Orta CA (2004) Self-assembly and crystallization behavior of a double-crystalline polyethylene-block-poly(ethylene oxide) diblock copolymer. Polymer 45 8181-8193... 

Another type of remarkable double crystalline materials that have been synthesized and characterized by Balsamo et al. are ABC triblock terpolymers composed of polystyrene, polyethylene and poly(ir-caprolactone) (PS-5-PE-6-PCL or SEC) [51-54,57,63]. The morphology, nucleation and crystallization of such copolymers have been recently reviewed [3]. It is interesting to mention that in such terpolymers the PE block induces an antinucleation effect [3,63] on its covalently bonded neighboring PCL block, a remarkable effect that has only been observed in this tjq >e of triblock terpolymer. Diblock copolymers or triblock terpolymers with two crystallizing blocks can display aU possible effects from the nucleation point of view of one crystallizing block on the other. One block can cause nucleation of the other, or cause no effect, or in the other extreme of behavior induce antinucleation. In addition to the... 

Minamitake, Y., Gref, R., Hrkach, J., Peracchia, M. T., Domb, A., and Langer, R., 1994, Injectable nanospheres made of biodegradable polyethylene glycol-poly(lactic-co-glycolic) acid diblock copolymers. Paper in preparation. 

The phase behavior can additionally be manipulated by adding block-selective solvents (low-molecular-weight solvents or polymers) [51]. A particularly important example is poly(ethylene oxide)-Wock-poly(propylene oxide)-h/ock-poly(ethylene oxide) triblock copolymers in aqueous solvents (selective with respect to polyethylene oxide) [52]. Along a similar line, bicontinuous microemulsions can be achieved in symmetric temaiy blends consisting of diblock copolymers mixed with the two corresponding homopolymers [53]. 

Wang W, Liu R, Li Z, Meng C, Wu Q, Zhu F (2010) Synthesis and self-assembly of new double-crystalline amphiphilic polyethylene-h/ock-poly[oligo(ethylene glycol) methyl ether methacrylate] coil-brush diblock copolymer. Macromol Chem Phys 211 1452-1459... 

Reducing the interfacial tension between the two phases which leads to a finer dispersion of one phase in the other. For example, the incorporation of 1% poly(styrene-( -ethylene) diblock copolymer in a blend of polystyrene and polyethylene results in a reduction in interfacial tension from 4.5 to 1.0 dyne cm . ... 

Wang, Y.B. and Hillmyer, M A. (2001) Polyethylene-poly(L-lactide) diblock copolymers Synthesis and compatibiliza-tion of poly(L-lactide)/polyethylene blends. Journal of Polymer Science Part A Polymer Chemistry, 39,2755 2766. 

Diblock copolymers (e.g., low molecular weight polyethylene-poly(ethyle-nepropylene)) are added to waxy crude oils to reduce their tendency to solidify on the walls of pipes, which ultimately results in blocking the flow. In small quantities, these copol5mers co-crystallize with crude oil, forming a weaker gel which... 

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