Ethylene oxide/styrene block polymer

Solution Properties of Styrene-Ethylene Oxide Block Polymers. During the course of our studies of synthetic routes to poly(styrene-b-ethylene oxide), we have undertaken an investigation of the solution... 

There have been numerous studies employing calorimetric(19), dynamic mechanical, ( ) dielectric, ( ) and morphological(23,24) techniques to elucidate the solid-state behavior of styrene-ethylene oxide block copolymers. These measurements have focused on transition-temperature phenomena, and they have provided reference data on the bulk properties of the copolymers. The evidence accumulated to date indicates that PS and PEO are incompatible in the bulk. While this appears true, in general, one cannot rule out the possibility that PS and PEO have some limited degree of miscibility in the copolymers. It is also unknown, at this time, what influence an interface (e.g., the air-polymer interface) has... 

Wilhelm M, Zhao CL, Wang YC, Xu RE, Winnik MA, Mura JL, Riess G, Croucher MD (1991) Polymer micelle formation. 3. Poly(styrene-ethylene oxide) block copolymer micelle... 

Nakamura K, Endo R, Takada M (1976) Surface properties of styrene-ethylene oxide block copolymers. J Polym Sci Polym Phys 14 1287-1295... 

Studies on the interaction between surfactants and styrene-ethylene oxide block co-polymers, however, indicate that the polymers exhibit, in the presence of surfactant, typical polyelectrolyte character. This, it has been suggested [264], is due to interaction repulsions between like charges of the NaDS ions adsorbed onto the polyoxyethylene blocks. Investigating the interaction of the same detergent with methylcellulose and poly(vinyl alcohol), Lewis and Robinson [265] also observed the polyelectrolyte character of the polymer-surfactant complexes. A complex between non-ionic surfactants and a polycarboxylic acid in water can solubilize oil-soluble dyes below the surfactant CMC [268]. The complex containing the solubilizate can be precipitated the solubilizate remains in the precipitated complex and is leached out only slowly on placing the precipitate in fresh solvent. This has potential pharmaceutical implications. Halothane uptake by coacervate systems of gelatin-benzalkonium [269] has... 

An important group of surface-active nonionic synthetic polymers (nonionic emulsifiers) are ethylene oxide (block) (co)polymers. They have been widely researched and some interesting results on their behavior in water have been obtained [33]. Amphiphilic PEO copolymers are currently of interest in such applications as polymer emulsifiers, rheology modifiers, drug carriers, polymer blend compatibilizers, and phase transfer catalysts. Examples are block copolymers of EO and styrene, graft or block copolymers with PEO branches anchored to a hydrophilic backbone, and star-shaped macromolecules with PEO arms attached to a hydrophobic core. One of the most interesting findings is that some block micelle systems in fact exists in two populations, i.e., a bimodal size distribution. 

Riess G, Rogez D (1982) Micellization of poly(styrene-b-ethylene oxide) block copolymers, ACS Polym Prepr (Div Polym Chem) 23 19-20... 

The reactive end of a living polymer attacks a suitable group on a dead polymer Pji and grafts on Pjj as shown by Schreiber (15), who grafted living polystyrene on dead poly (methyl methacrylate). Such a procedure may lead to cross linking or to the formation of a loop, if both ends of the living polymer are active. Other block polymers prepared by this technique are polymers of styrene and ethylene oxide (14), polymers of styrene and dimethylsiloxanes (13), and polymers of styrene and vinylpyridine (16). 

Similar solvent effects influence the morphology of block polymers of a crystallizable and a noncrystallizable component also. In principle, the poly(ethylene oxide) blocks of the biblock polymer, poly(styrene-Z -ethylene... 

TLC has been used in the study of many homopolymers polystyrene, poly(methyl methacrylate), poly(ethylene oxide), polyisoprene, poly(vinyl acetate), poly(vinyl chloride) and polybutadiene. Their molecular weight, molecular-weight distributions, microstructure (stereo-regularity, isomerism and the content of polar end groups), isotope composition and branching have been studied. For copolymer characterisation (e.g. purity and compositional inhomogeneity), random copolymers such as styrene-methacrylate, and block copolymers such as styrene-butadiene, styrene-methyl methacrylate and styrene-ethylene oxide have been separated. A good review article on polymers... 

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... 

Richards, D. H., and M. SzwArc Block polymers of ethylene oxide and its analogues with styrene. Trans. Faraday Soc. 55, 1644 (1959). 

Polymeric steric stabilizer such as poly(vinylpyrrolidone) (PVPo),poly(acrylic acid), poly(hydroxypropyl)cellulose, etc., are used to prepare monodisperse polymer in dispersion polymerization of monomers such as alkyl acrylates and methacrylates, and styrene in polar media. AB and ABA block copolymers are a second type of steric stabilizer which can be used in dispersion polymerization. For example, the poly(styrene-h-ethylene oxide) was recently used by Winnik et al. [6] in the dispersion polymerization of styrene in methanol. 

SCBs play an important role in the formation of other block copolymers. For example, the relatively less nucleophilic poly(ethylene oxide) oxyanion cannot initiate the polymerization of styrene, which needs a more nucleophilic alkyllithium initiator. To enable the synthesis of multi-block copolymers from various combinations of monomers by anionic mechanisms, it is important to modify the reactivity of the growing anionic chain end of each polymer so as to attack the co-monomer. There have only been a few reports on the polymerization of styrene initiated by an oxyanion (see <2001MM4384> and references cited). Thus, there exists a need for a transitional species that is capable of converting oxyanions into carbanions. In 2000, Kawakami and co-workers came up with the concept of the carbanion pump , in which the ring-strain energy of the SCB is harnessed to convert an oxyanion into a carbanion (Scheme 13) <2000MI527>. 

Th-FFF can be applied to almost all kinds of synthetic polymers, like polystyrene, polyolefins, polybutadiene, poly(methyl methacrylate), polyisoprene, polysulfone, polycarbonate, nitrocelluloses and even block copolymers [114,194,220]. For some polymers like polyolefins, with a small thermal diffusion coefficient, high temperature Th-FFF has to be applied [221]. Similarly, hydrophilic polymers in water are rarely characterized by Th-FFF, due to the lack of a significant thermal diffusion (exceptions so far poly(ethylene oxide), poly(vi-nyl pyrrolidone) and poly(styrene sulfonate)) [222]. Thus Th-FFF has evolved as a technique for separating synthetic polymers in organic solvents [194]. More recently, both aqueous and non-aqueous particle suspensions, along with mixtures of polymers and particles, have been shown to be separable [215]. 

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... 

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