Copolymers surface-active graft

A new class of amphiphilic, surface-active graft copolymers, hydrophobically modified hydroxyethyl celluloses (HM-HEC s), are comprised of a cellulose backbone with short polyethylene oxide (PEO) and grafted alkyl side chains. They are excellent steric stabilizers of 0/W emulsions. 

The behavior of surface-active graft copolymers In aqueous solutions has been the subject of much interest and study by the authors [1-3] and others [4-8]. It has been shown that these polymers self-associate in aqueous solutions, forming micelle-like aggregates among the less water-soluble species on the chain. These aggregates may form either intra- or intermolecularly. The net effect of the latter process is the formation of hydrogels with dispersed hydrophobic microdomains. 

Two approaches have been used successfully in producing dispersed phase hydrogels from surface-active graft copolymers. In one approach, the polymer, which is insoluble in water due to its high alkyl side chain content, is solubilized in ethanol/water solutions, permitting the side chains to come into close contact and form hydrophobic microphases spontaneously. In the second approach, we have used surfactant at... 

Alkenylsuccinic anhydrides made from several linear alpha olefins are used in paper sizing, detergents, and other uses. Sulfosuccinic acid esters serve as surface active agents. Alkyd resins (qv) are used as surface coatings. Chlorendric anhydride [115-27-5] is used as a flame resistant component (see Flame retardants). Tetrahydrophthalic acid [88-98-2] and hexahydrophthalic anhydride [85-42-7] have specialty resin appHcations. Gas barrier films made by grafting maleic anhydride to polypropylene [25085-53-4] film are used in food packaging (qv). Poly(maleic anhydride) [24937-72-2] is used as a scale preventer and corrosion inhibitor (see Corrosion and corrosion control). Maleic anhydride forms copolymers with ethylene glycol methyl vinyl ethers which are partially esterified for biomedical and pharmaceutical uses (189) (see Pharmaceuticals). 

Surface active agents are important components of foam formulations. They decrease the surface tension of the system and facilitate the dispersion of water in the hydrophobic resin. In addition they can aid nucleation, stabilise the foam and control cell structure. A wide range of such agents, both ionic and non-ionic, has been used at various times but the success of the one-shot process has been due in no small measure to the development of the water-soluble polyether siloxanes. These are either block or graft copolymers of a polydimethylsiloxane with a polyalkylene oxide (the latter usually an ethylene oxide-propylene oxide copolymer). Since these materials are susceptible to hydrolysis they should be used within a few days of mixing with water. 

Such copolymers may also be effectively employed to enhance adhesion between surfaces of different composition using copolymers with groups having different activity. These complex systems obtained by reaction (graft, block, homopolymers) have been termed interpolymer. For these and additional reasons, increasing amounts of block and graft copolymers are produced by the major plastics companies throughout the world. 

The peroxidation procedure, which is the least often used of all the irradiation techniques, involves irradiation of the substrate in the presence of air or oxygen. This produces diperoxides and hydroperoxides on the surface of fhe subsfrafe, which are stable, and the substrate can be stored until the combination with a monomer is possible. Monomer, with or without solvent, is then reacted with the activated peroxy trunk polymer in air or under vacuum at elevated temperatures to form the graft copolymer. The advantage of this method is the relatively long shelf life of fhe infermediate peroxy trunk polymers before the final grafting step. ... 

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. 

Exponents 0.6 and 0.8 deviate from both the homogeneous nucleation and micellar models. Thus the bimolecular termination between the growing radicals is suppressed. This behavior may also result from the surface activity of the graft copolymer formed. The higher the surface activity of graft copolymer the higher the particle number. This behavior would indicates that the graft copolymer formed within the particles (with DBP) is more efficient. 

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