Surfactant copolymer

Aggregation of Block Copolymer Surfactants 3.1 Tethering Processes... 

Finally, we have designed and synthesized a series of block copolymer surfactants for C02 applications. It was anticipated that these materials would self-assemble in a C02 continuous phase to form micelles with a C02-phobic core and a C02-philic corona. For example, fluorocarbon-hydrocarbon block copolymers of PFOA and PS were synthesized utilizing controlled free radical methods [104]. Small angle neutron scattering studies have demonstrated that block copolymers of this type do indeed self-assemble in solution to form multimolecular micelles [117]. Figure 5 depicts a schematic representation of the micelles formed by these amphiphilic diblock copolymers in C02. Another block copolymer which has proven useful in the stabilization of colloidal particles is the siloxane based stabilizer PS-fr-PDMS [118,119]. Chemical... 

Chu B, Zhou Z (1996) Physical chemistry of polyoxyalkylene block copolymer surfactants. In Nace VN (ed) Nonionic surfactants polyoxyalkylene block copolymers, vol 60. Marcel Dekker, New York... 

V.M. Nace, Nonionic Surfactants Polyoxyalkylene Block Copolymers, Surfactant Science Series, Vol. 63, Marcel Dekker, New York, USA, 1996. 

Jain S, Bates FS (2003) On the origins of morphological complexity in block copolymer surfactants. Science 300 460-464... 

Herein we summarise our recent progress in the exploitation of ATRP for the synthesis of controlled-structure block copolymer surfactants and dispersants. 

Chapman TM, Hillyer GL, Mahan EJ, Shaffer KA. Hydraamphiphiles novel hnear dendritic block copolymer surfactants. J Am Chem Soc 1994 116 11195-11196. 

The dispersion polymerization of styrene in supercritical CO2 using amphiphilic diblock copolymers to impart steric stabilization has been investigated. Lipophilic, C02-insoluble materials can be effectively emulsified in carbon dioxide using amphiphilic diblock copolymer surfactants. The resulting high yield (> 90%) of polystyrene is obtained in the form of a stable polymer colloid comprised of submicron-sized particles (Canelas et al., 1996). 

The concentration of the surfactant in the monomer phase was found to be critical to the formation of a stable polymer foam [129,130]. At least 4% surfactant, relative to the total oil phase, was required for PolyHIPE formation, whereas formulations containing above 80% resulted in the formation of an unconnected or closed-cell material. Surfactant levels between 20 and 50% were deemed to be optimum at all internal phase volumes. Additionally, Litt et aL [131] demonstrated that block copolymer surfactants can be used to prepare water-in-styrene HIPEs. From these, highly porous uncrosslinked polystyrene PolyHIPE materials were synthesised. 

The idea of the preparation of porous polymers from high internal phase emulsions had been reported prior to the publication of the PolyHIPE patent [128]. About twenty years previously, Bartl and von Bonin [148,149] described the polymerisation of water-insoluble vinyl monomers, such as styrene and methyl methacrylate, in w/o HIPEs, stabilised by styrene-ethyleneoxide graft copolymers. In this way, HIPEs of approximately 85% internal phase volume could be prepared. On polymerisation, solid, closed-cell monolithic polymers were obtained. Similarly, Riess and coworkers [150] had described the preparation of closed-cell porous polystyrene from HIPEs of water in styrene, stabilised by poly(styrene-ethyleneoxide) block copolymer surfactants, with internal phase volumes of up to 80%. 

Alexandridis P, Hatton TA. Polyethylene oxide)-poly(propylene oxide)- poly(ethylene oxide) block copolymer surfactants in aqueous solutions and at interfaces thermodynamics, structure, dynamics, and modeling (review). Colloid Surf A Physicochem Eng Aspects 1995 96 1 16. 

Edens, M. W. (1996). Applications of polyoxyethylene block copolymer surfactants. In Nonionic surfactants. Polyoxyalkylene block copolymers, Vol. 60, (ed. V. N. Nace), p. 185. Marcel Dekker, New York. 

Pepic, I., N. Jalsenjak, and I. Jalsenjak. 2004. Micellar solutions of triblock copolymer surfactants... 

It was previously reported that the homopolymer surfactant PFOA successfully stabilized poly(methyl methacrylate) (PMMA) dispersion polymerizations (DeSimone et al., 1994 Hsiao et ah, 1995), but was not successful for styrene dispersion polymerizations (Canelas et al., 1996). In these styrene polymerizations, the C02 pressure used was 204 bar. However, later studies showed that both PFOA and poly(l,l-dihydroper-fluorooctyl methacrylate) (PFOMA) could stabilize polystyrene (PS) particles (Shiho and DeSimone, 1999) when a higher pressure was used. These polymerizations were conducted at 370 bar, 65 °C, and the particle size could be varied from 3 to 10 pm by varying the concentration of stabilizer. These homopolymer surfactants are less expensive and easier to synthesize than block copolymer surfactants and provide access to a large range of particle sizes. 

I. Block Copolymer Surfactants for Carbon Dioxide Applications. Macromolecules 1994, 27, 5527-5532. 

The best results were obtained by using the block copolymer surfactant SE3030 together with the nonionic initiator PEGA200 which supports interface stabilization and improves the structural perfection (Fig. 18a) of the polystyrene capsule morphology. 

Jain S, Gong X et al. (2006) Disordered network state in hydrated block-copolymer surfactants. Phys Rev Lett 96 138304/1... 

The 1963 Nobel Prize in Chemistry was awarded to Karl Ziegler and Giulio Natta for their research on catalysts (see Catalysis) for the oligomerization see Oligomer) and polymerization see Polymerization) of alkenes under mild conditions of temperature and pressure. Their discoveries have grown into a multibillion dollar industry for the production of plastics, elastomers, and inexpensive feedstock chemicals for copolymers, surfactants, and other useM additives. ... 

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