Block Copolymers Styrene-Ethylene Oxide

Ethylene oxide/styrene block copolymers have been further free-radical copolymerized with other ethylenically unsaturated compounds such as methyl methacrylate and methacrylic acid in benzene, tetrahydrofuran, and dimethylformamide (176). Correlations were made between reactivity ratio and solvent dielectric constant, as well as between solubility parameters of reaction solvent and growing polymer chains with marked effects apparent. Gel permeation chromatography of diblock and triblock copolymers based on polystyrene and poly(ethylene oxide) has revealed interesting molecular characteristics (177). Such block copolymers have an amphiphilic character. In aqueous solution, the polymers form spherical micells with a polystyrene core and a poly(ethylene oxide) outer sheath. The investigations used an aqueous-methanolic solution and were able to ascertain block copolymer structures and to estimate the impurities in the diblock copolymer. 

Polyblends with Soft Matrix. Polyblends in which both phases are soft are mixtures of different rubbers. Treads of automobile tires are made of polyblends of SBR with either natural rubber or cts-polybutadiene. Co vulcanization of EPDM with various rubbers is discussed in the chapter of M. E. Woods and T. R. Mass. Relaxation behavior of blends of EVA rubber with styrene/ethylene-butylene/styrene block copolymer and of poly (ethylene oxide) with ethylene oxide/propylene oxide/ethylene oxide block copolymer were studied by M. Shen, U. Mehra, L. Toy, and K. Biliyar. 

Styrene/DVB resin, chloromethylated aminated. See Chloromethylated aminated styrene-divinylbenzene resin Styrene epoxide. See Styrene oxide Styrene-ethylene/butylene-styrene block copolymer CAS 66070-58-4... 

Polycarbonate blends with special thermoplastic elastomers, e.g., styrene-ethylene-butylene styrene-block-copolymers (SEES), provide excellent resistance to photo-oxidative degradation. 

B-90 and B-91, respectively.390 Another route coupled with cationic ring-opening polymerizations is accomplished for polymer B-92 with the use of a hydroxyl-functionalized initiator with a C—Br terminal, where the OH group initiates the cationic polymerizations of 1,3-dioxepane in the presence of triflic acid.329 Polyethylene oxide)-based block copolymers B-93 are obtained by living anionic polymerization of ethylene oxide and the subsequent transformation of the hydroxyl terminal into a reactive C—Br terminal with 2-bromopropionyl bromide, followed by the copper-catalyzed radical polymerization of styrene.391... 

By the same method of living radical polymerisation, a series of block copolymers of poly(ethylene oxide-styrene) with narrow polydispersity were synthesised by the following two-step approach [96]. Initially, living anionic polymerisation of ethylene oxide with sodium-4-oxy-2,2,6,6-tetramethyl-l-piperidinoxyl as initiator yields polyethylene oxide with ARs at the chain end ... 

The anionic polymerization of 9-vinylanthracene gives only low molecular weight products [342], which agrees with Rembaum s and Eisenberg s results [355]. Stolka et al. [342] found no proof of the proposed [337,355] across-the-ring addition instead, the IR and UV spectra of their polymers indicated the conventional 1,2-addition pattern. 2-Propenyl-l-anthracene could not be polymerized anionically [342], Attempts to initiate polymerizations by means of electron-transfer-type initiators (e.g., sodium naphthalene and sodium biphenyl) were unsuccessful [341,342,353,354], The polymerization of 1-vinylpyrene initiated by electron-transfer initiators showed the characteristics of a living polymer system [356,357], Block copolymers of the AB and ABA type were synthesized with ethylene oxide, styrene and isopropene [357],... 

Block copolymers combine different physical or/and chemical properties in one polymer. Hence, some new properties (e.g., amphiphUicity) can be achieved for this type of polymer. Because of their unique properties, copolymers are used everywhere in everyday life. For example, poly(ethylene oxide) (PEO) and poly(propyl-ene oxide) (PPO) block copolymers (PEO-PPO-PEO, commercially known as Pluronics) are widely used as nonionic surfactants in daily care products. One commercial thermoplastic elastomer is made from styrene-butadiene-styrene (SBS) triblock copolymers. 

Different series of DHBCs were prepared from anionically synthesized poly(p-tert-but05 styrene-b-ethylene oxide) (PtBOS-PEO) precursors [12]. Post polymerization acidic hydrolysis of the PtBOS block resulted in poly(p-hydroxystyrene-b-ethylene oxide) (PHOS-PEO) copolymers. Further fimctionalization of the PHOS block via a Mannich type aminomethylation reaction gave the poly[3,5-bis(dimethylaminomethylene)hydroxystyrene-b-ethylene oxide] (PNHOS-PEO) copolymers, as testified by FT-IR and NMR experiments. In these copolymers the PNHOS block carries two dimethylamino groups per monomeric unit that can be protonated in acidic media and weakly acidic phenolic groups that have their own pH sensitivity. The PNHOS-PEO block copolymers were further quatemized with... 

Polylphenylene oxide) Styrene-ethylene block copolymer... 

Polyall lene Oxide Block Copolymers. The higher alkylene oxides derived from propjiene, butylene, styrene (qv), and cyclohexene react with active oxygens in a manner analogous to the reaction of ethylene oxide. Because the hydrophilic oxygen constitutes a smaller proportion of these molecules, the net effect is that the oxides, unlike ethylene oxide, are hydrophobic. The higher oxides are not used commercially as surfactant raw materials except for minor quantities that are employed as chain terminators in polyoxyethylene surfactants to lower the foaming tendency. The hydrophobic nature of propylene oxide units, —CH(CH2)CH20—, has been utilized in several ways in the manufacture of surfactants. Manufacture, properties, and uses of poly(oxyethylene- (9-oxypropylene) have been reviewed (98). 

A. Mayer et al. examined poly(dimethylsiloxane)-bIock-poly(ethylene oxide) (PDMS-b-PEO), poly(styrene)-f)Iock-poly(ethylene oxide) (PS-b-PEO), polystyrene-block-poly(methacryhc acid) (PS-b-PMAA) as amphiphihc block copolymers with regard to their properties in stabilizing colloidal metal nanoparticles [37, 49]. All three polymers are successfully used to stabihze various transition metal coUoids... 

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. 

The range of monomers that can be incorporated into block copolymers by the living anionic route includes not only the carbon-carbon double-bond monomers susceptible to anionic polymerization but also certain cyclic monomers, such as ethylene oxide, propylene sulfide, lactams, lactones, and cyclic siloxanes (Chap. 7). Thus one can synthesize block copolymers involving each of the two types of monomers. Some of these combinations require an appropriate adjustment of the propagating center prior to the addition of the cyclic monomer. For example, carbanions from monomers such as styrene or methyl methacrylate are not sufficiently nucleophilic to polymerize lactones. The block copolymer with a lactone can be synthesized if one adds a small amount of ethylene oxide to the living polystyryl system to convert propagating centers to alkoxide ions prior to adding the lactone monomer. 

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