EO/PO block copolymer

It is important to recognize that the following analytical methods essentially determine EO-PO ratio ( H NMR, IR, cleavage methods) or even simply alkylene oxide content (compleximetric methods) of the analyte, and as such are not specific quantitative or qualitative methods for poloxamers, since EO-PO copolymers of a different structure (for instance, random copolymers, or PO-EO-PO block copolymers) may respond to the methods in a way indistinguishable from poloxamers. The principal technique that permits definitive identification of a sample as a poloxamer is C NMR, which allows structural details, such as the distribution of EO and PO units along the polymer chain, to be elucidated [10]. 

Nonionic surfactants, including EO-PO block copolymers, may be readily separated from anionic surfactants by a simple batch ion exchange method [21] analytical separation of EO-PO copolymers from other nonionic surfactants is possible by thin-layer chromatography (TLC) [22,23] and paper chromatography [24], and EO-PO copolymers may themselves be separated into narrow molecular weight fractions on a preparative scale by gel permeation chromatography (GPC) [25]. 

Surfactants used as lubricants are added to polymer resins to improve the flow characteristics of the plastic during processing they also stabilise the cells of polyurethane foams during the foaming process. Surfactants are either nonionic (e.g. fatty amides and alcohols), cationic, anionic (dominating class e.g. alkylbenzene sulfonates), zwitterionic, hetero-element or polymeric (e.g. EO-PO block copolymers). Fluorinated anionic surfactants or super surfactants enable a variety of surfaces normally regarded as difficult to wet. These include PE and PP any product required to wet the surface of these polymers will benefit from inclusion of fluorosurfactants. Surfactants are frequently multicomponent formulations, based on petro- or oleochemicals. 

The surfactant properties of polymeric silicone surfactants are markedly different from those of hydrocarbon polymeric surfactants such as the ethylene oxide/propylene oxide (EO/PO) block copolymers. Comparable silicone surfactants often give lower surface tension and silicone surfactants often self-assemble in aqueous solution to form bilayer phases and vesicles rather than micelles and gel phases. The skin feel and lubricity properties of silicone surfactants do not appear to have any parallel amongst hydrocarbon polymeric surfactants. 

These inerts are mostly polymeric or oligomeric in nature and can be both nonionic and anionic. They have multiple binding / interaction sites to the interface, so that a displacement becomes improbable. Several materials have been made available to the industry [6d,ej. The chemistries range from sulfonic condensates (Morwet) or lignin sul-phonates (Reaxx) to EO-PO-block copolymers (Pluronics), comb graft polymers, acrylate based copolymers or various other block copolymers. 

Addition of EO-PO block copolymers to detergents to increase solubility... 

Tetronk(9. [BASF] EO/PO block copolymers emulsifler, thickener, wetting agent, dispersant, solubilizer, sta-bilizo-, antistat to cosmetics, pharmaceutic, petroleum, detergents, molding powdm, metal treatment, emulsion polymerization, paints, cutting fluids, rubber vulcanization. 

Hoe S. [Hoechst Cdanese/Colwants Surf.] Quaternaries, alcohol ethoxy-lates/propoxylates, EO/PO block copolymers, ohxer surfactants f< clear conditioners and conditioning shampoos, cosmetics, plant protection. 

The plasticising activity of ethoxylated alkylphenols and EO/PO block-copolymers depends on the number (m) of the EO units in a surfactant molecule. Ethoxylated alkylphenols with m>40 have a substantial effect on the viscosity reduction of HWCS. It may be connected with the fact that they can form rather thick hydrated layers when adsorbing on the particles, which play the role of a structure-mechanical barrier. The addition of ethoxylated alkylphenols with m<40 produce a thickening effect on the suspensions which may be connected with the features of coal particle wetting by aqueous surfactant solutions. 

The general structure of ethylene oxide/propylene oxide (EO/PO) block copolymers (3) is as follows ... 

EO/PO block copolymers represent an important class of surfactants because of their low-foaming characteristics. They are used in machine dishwashing detergents, as well as a variety of specialty applications that require low- or no-foaming surfactants. They find application as rinse aids, solubilizers for fragrances, and as thickeners and gelling agents. 

Production of PO/EO/PO block copolymers involves the opposite sequence, in which a block of EO is propoxylated. 

In general, increasing EO content increases the water solubility, improves the ability to thicken and form gels, and reduces wetting. PO/EO/PO block copolymers foam less, are more effective defoamers, and have less of a tendency to form gels in aqueous solutions than EO/PO/EO block copolymers. 

Esterified nonionic surfactants are prepared from ether-containing polyhydric alcohols that include derivatives of EO and PO snch as polyethylene glycol (PEG), polypropylene glycol (PPG), EO/PO block copolymers, polyglycerin that is prepared by thermal dehydration with basic catalyst, and ethoxylated glycerin (Schane 1.9). 

Classification of EO/PO Block Copolymers, Uses, Commercial Names, and Main Producers... 

Another example of the influence of the difference in kinetic constant (k2i < k ) is the necessity for high degree of ethoxylation (mole of EO/mole of substrate hydroxyl) to obtain EO/PO block copolymer with high concentration of primary hydroxyls when the EO is fed after PO reaction, as shown in Figure 15.4 [18]. 

Many aspects must be considered in the production processes of EO/PO block copolymers concerning raw materials, their storage and subsequent purification, reactor configurations, separation technologies, chanical and physical analysis, and quality and safety standards. 

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