Cross-linking, surfactant

Non cross-linking, surfactant protected, polyvinyl actetate emulsion. 

Surfactants evaluated in surfactant-enhanced alkaline flooding include internal olefin sulfonates (259,261), linear alkyl xylene sulfonates (262), petroleum sulfonates (262), alcohol ethoxysulfates (258,261,263), and alcohol ethoxylates/anionic surfactants (257). Water-thickening polymers, either xanthan or polyacrylamide, can reduce injected fluid mobiHty in alkaline flooding (264) and surfactant-enhanced alkaline flooding (259,263). The combined use of alkah, surfactant, and water-thickening polymer has been termed the alkaH—surfactant—polymer (ASP) process. Cross-linked polymers have been used to increase volumetric sweep efficiency of surfactant—polymer—alkaline agent formulations (265). 

Condensation cure can also be carried out ia emulsions (200—209). In this case, the cross-linker and polydimethylsiloxanediol are emulsified usiag anionic, cationic, or nonionic surfactants ia water, and a condensation catalyst such as dibutyltin dilaurate is added. The polymer can then undergo cross-linking, forming a continuous film when the water is evaporated. 

Cross-linked xylan-based microparticles are produced by the emulsification of an alkaline solution of xylan with a lipophilic phase formed by a mixture of chloroform and cyclohexane by using 5% (w/v) sorbitan triesterate as the surfactant. Subsequently, the cross-linking reaction is carried out for 30 minutes with 5% (w/v) terephthaloyl chloride in order to yield a hard and rigid polymeric shell (Nagashima et al., 2008). 

The most effective of these include immobilization [80], lipid coating [81], surfactant coating [82], use of cross-linked enzyme crystals [83], cross-linked enzyme aggregates [84], and membrane reactors [85]. 

Chrambach, A Rodbard, D, Polyacrylamide Gel Electrophoresis, Science 172, 440, 1971. Chu, B Yeh, F Sokolov, EL Starodoubtsev, SG Khokhlov, AR, Interaction of Slightly Cross-linked Gels of Poly(diallyldimethylammonium chloride) with Surfactants, Macromolecules 28, 8447, 1995. 

Oil-field chemistry has undergone major changes since the publication of earlier books on this subject Enhanced oil recovery research has shifted from processes in which surfactants and polymers are the primary promoters of increased oil production to processes in which surfactants are additives to improve the incremental oil recovery provided by steam and miscible gas injection fluids. Improved and more cost-effective cross-linked polymer systems have resulted from a better understanding of chemical cross-links in polysaccharides and of the rheological behavior of cross-linked fluids. The thrust of completion and hydraulic fracturing chemical research has shifted somewhat from systems designed for ever deeper, hotter formations to chemicals, particularly polymers, that exhibit improved cost effectiveness at more moderate reservoir conditions. 

Many commercially important polymers are produced via emulsion polymerization. This is also one of the most common methods to produce dye-doped beads. A dye is added to the mixture of monomers prior to initiating the polymerization and is either noncovalently entrapped or is copolymerized. The second method ensures that no leaching will occur from the particle but requires modification of the dye (typically by providing it with a double bond). This method is most common for preparation of pH-sensitive beads where a pH indicator is entrapped inside cross-linked polyacrylamide particles. The size of the beads can be tuned over a wide range so that preparation of both nano- and microbeads is possible. Despite thorough washing the surfactants are rather difficult to remove completely and their traces can influence the performance of some biological systems. 

A new family of hexagonal mesoporous all-germanium semiconductors was prepared by the surfactant-assisted cross-linking polymerization reaction of Zintl [Geg]" anions (Scheme 1) with Ge(lV) bridges in formamide/ethylenediamine solution (1) [43]. 

The early attempts to produce mesostructured metal chalcogenide involved surfactant-templated cross-linking polymerization of Zintl clusters (MQ4, M4Q10 and Sn2Qe M = Ge, Sn Q = S, Se, Te) with various metal ions (Hg, Cd, Pt, ... 

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