Diblock copolymer, polyethylene

Annis B K, Noid D W, Sumpter B G, Reffner J R and Wunderlich B 1992 Application of atomic force microscopy (AFM) to a block copolymer and an extended chain polyethylene Makromol. Chem., Rapid. Commun. 13 169 Annis B K, Schwark D W, Reffner J R, Thomas E L and Wunderlich B 1992 Determination of surface morphology of diblock copolymers of styrene and butadiene by atomic force microscopy Makromol. Chem. 193 2589... 

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-... 

An attractive ag lication offered by these last diblock copolymers is their use as blending aids (or "emulgators") for mixtures of homopolystyrene (PS) and polyethylene (PE, both low and high density). In that capacity they perform indeed two important functions (8) ... 

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

Pharmaceutical research on polymeric micelles has mainly focused on two kinds of block copolymers, namely, AB block copolymers or diblock copolymers and ABA or BAB block copolymers known as triblock copolymers (Bader et al., 1984 Yokoyama et al., 1990,1991 Kwon and Okano, 1996, 1999 Kwon, 1998, 2003 Alakahov and Kabanov, 1998). The most common hydrophilic block (A) of the block copolymers is polyethylene oxide (PEO). This polymer is highly hydrated through hydrogen bonding and sterically stabilizes surfaces of the polymeric micelles in aqueous systems. 

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. 

Desai, H., et al. (2006), Micellar characteristics of diblock polyacrylate-polyethylene oxide copolymers in aqueous media, Eur. Polym. J., 42(3), 593-601. 

Xu, G. Chung, T.C. Borane chain transfer agent in metallocene-mediated olefin polymerization synthesis of borane-terminated polyethylene and diblock copolymers containing polyethylene and polar polymer. J. Am. Chem. Soc. 1999,121, 6763. 

In analogy to lipids, amphiphilic block copolymers, i.e., macromolecules composed of at least one hydrophilic and one hydrophobic, covalently linked, polymer chains can form in aqueous solutions vesicles the so-called polymersomes. Generally, in self-assembling copolymer solutions, a rich diversity of morphologies is possible. An overview of the various factors important for vesicle formation, including copolymer architecture, presence of additives, solvent composition, and temperature, is given in [19]. To illustrate polymersome structures we reproduce from [21] on the top row of Fig. 2 cryo-TEM images of vesicles formed by 1.0 wt % aqueous solution of PEO- -PBD (PEO, polyethylene oxide PBD, polybutadiene) diblock copolymer for three different sizes of the PEO and PBD blocks. 

Linear low-density polyethylene (LLDPE) and PS resins were the same as described previously (Chapter 21). The various block copolymers that were used as compatibilizers have also been described (I). A series of crystalline copolymers (Q series) was prepared by hydrogenation of diblock and triblock copolymers of styrene and butadiene [styrene-hydrogenated butadiene (SEB) and styrene-hydrogenated butadiene—styrene (SEBS)J (1). Triblock copolymers of styrene and butadiene [styrene-butadiene-styrene (SBS)] and a noncrystalline hydrogenated block copolymer (SEBS) (Kraton) were supplied by Shell Chemical Co. Diblock copolymers of styrene and butadiene [styrene-butadiene (SB) (Vector)] were obtained from Dexco Polymers. The characteristics of the resins are given in Table I. 

Pioneering work by Bates, Lodge and co-workers [5-12] demonstrated that the addition of diblock copolymer (A-B) into the mixture of its corresponding homopolymer A and B drives self-assembly into varied structures including droplet-type microemulsions [8], bicontinuous micro emulsions [5, 6, 8, 10, 12], hexagonal phases [10, 11] and lamellar phases [5, 8, 12]. Figure 7.1 shows a typical temperature-composition phase diagram of symmetric polyethylene (PE)/polyethylenepropylene (PEP)/PE-PEP mixtures [5]. To... 

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. 

The last system that will be compared is that of polystyrene and polyethylene. In these studies,35the tensile properties of the blend with an added copolymer were examined. These studies showed that the addition of 10% diblock copolymer (50/50 composition, Mw = 80,000) to a blend that is 80% polystyrene produces an ultimate strength of 33 MPa, whereas the addition of the same amount of a random copolymer (67% polyethylene, Mw =... 

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... 

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