Polyurethane containing hydrophilic

It has been assumed (1A9) that volatilization of the acetic acid occurs during the drying cycle of the urethane latices, which then no longer contain hydrophilic amine acetate groups. Rembaum and coworkers (152-156) also reported the preparation of cationic polyurethanes and various applications of these polymers, which were termed "ionene polymers" because they contained ionic amines. 

Kozakiewicz J (1991) Polyurethanes and isocyanates containing hydrophilic groups as potential components of >rater-bome adhesives. Chapter 6. In Allen KW (ed) Adhesion 15. Elsevier, London, pp 80-101... 

Essentially nonionic soil-release agents comprise polyesters, polyamides, polyurethanes, polyepoxides and polyacetals. These have been used mainly on polyester and polyester/ cellulosic fabrics, either crosslinked to effect insolubilisation (if necessary) or by surface adsorption at relatively low temperature. Polyester soil-release finishes have been most important, particularly for polyester fibres and their blends with cellulosic fibres. These finishes, however, have much lower relative molecular mass (1000 to 100 000) than polyester fibres and hence contain a greater proportion of hydrophilic hydroxy groups. They have been particularly useful for application in laundering processes. These essentially nonionic polymers may be given anionic character by copolymerising with, for example, the carboxylated polymers mentioned earlier these hybrid types are generally applied with durable press finishes. 

Polyurethane hydrogels derived from UV curable urethane prepolymer and hydrophilic monomers were prepared and their properties were evaluated. The urethane prepolymer used in this study contained well-defined hard segments centered with a polyether-based soft segment and end-capped with methacrylate groups. The hydrophilic monomers studied were 2-hydroxyethyl methacrylate (HEMA), N-vinyl pyrrolidone, and glycerol methacrylate. Methacryloxypropyl tris(trimethysiloxy) silane (TRIS) was also used in some cases to modify properties. All compositions were UV... 

When a solvent is polar, a reservoir that reflects that must be developed. Hydrophilic polyurethanes were specifically designed to serve as reservoirs for polar solvents, although the inventors did not express their ideas in that manner. In many commercial cases, reservoir capacity ( the bottle ) is too large. The container swells as it absorbs. The nature of the material is to lose most of its physical strength as it swells. While we need the polarity, we also want to optimize the size of the bottle and strength of the material. The current library of hydrophilic prepolymers does not provide that flexibility, but we now know that we can build our own prepolymers with copolymers of propylene oxide (PO) and ethylene oxide (EO). 

The cells were entrapped in a hydrophilic polyurethane. This represents one technique of immobilization. With hydrophihc polyurethanes, a researcher has a choice of entrapment or adhesion. With adhesion, a broth containing the ceUs inoculates the polyurethane. The cells adhere to the surface via their natural adhesive systems. 

Prospective, multisite, uncontrolled clinical studies were conducted to study the effectiveness of the formulations and the acceptability of the polym ethane delivery system. The formulation was imbibed into 2.5-in. hydrophilic polyurethane foam discs (LMI, St. Charles, MI). Each disc contained 2.4 g of the formulation. The method of application was developed in tests that limited the active ingredient to the same amount or less than the monograph specifications for the formulation ingredients. Fourteen volunteers were given boxes containing 42 individually wrapped foam pads impregnated with the fonnulation and were asked to complete the questionnaire weekly. 

Hydrophilic polymers contain a commensurate amount of hydrophilic and hydrophobic fragments in macromolecular composition, including proteins, some polyurethanes and acrylate copolymers. Water is a good solvent for hydrophilic polymers, and therefore it often violates the original structure of the polymer on sorption of aqua solutions. Non-polar fragments, due to their macromolecular flexibility on sorption of aqua solutions, can associate and form areas of elevated hydrophoby to hamper the electrolyte motion. Hydrophilic sections of the chain encircled by the solvent are responsible for the electrolyte transfer. The majority of polymers cannot form fully hydrophobic areas because their polar and non-polar sections in macromolecules are frequently var3ung. 

Aqueous Systems. Type 6 in Table 2.5. Aqueous dispersions of polyurethanes that are slightly supported by ionic groups also undergo physical film formation. The binder consists of polymer chains that are coupled via urethane and urea groups, and contain basic or acid groups. Neutralization by salt formation provides the necessary hydrophilicity if the self-emulsifying properties resulting from incorporation of hydrophilic polyether radicals are insufficient. 

The use of water-containing miniemulsions (as described above) is Hmited to particular monomers for anionic polymerization. Since, in many cases, the initiator and active species are sensitive to water, the polymerization caimot be carried out in either water-in-oil or oil-in-water miniemulsions. The anionic polymerization of e-caprolactam in a non-aqueous miniemulsion was first reported in 2005 [103]. As the e-caprolactam monomer is hydrophilic, it was necessary to conduct the polymerization in an inverse miniemulsion. Unfortunately, the molten e-caprolactam-in-oil miniemulsions could not be stabilized efficiently, in contrast to dimethyl sulfoxide (DMSO)-in-oil miniemulsions. Therefore it was necessary to dissolve the e-caprolactam directly in DMSO, to form the dispersed phase. This synthetic strategy, which permitted the production of polyamide-6 nanoparticles, paved the way for a variety of water-sensitive reactions to be performed in miniemulsion nanodroplets, including the creation of hydrophihc polyurethane capsules and particles (see below). Subsequently, poly(e-caprolactone)... 

In the prepolymer-ionomer process , the compound which contains the moieties which are the precursors of ionic groups is incorporated in the polymer chain already at the stage of urethane prepolymer formation. Then they are neutralised, which results in the formation of a prepolymer-ionomer which is emulsified in water and eventually crosslinked. In this process, the prepolymer-ionomer is usually dissolved in a small amount of water-miscible solvent of high boiling point, e.g., N-methylpyrolidone, which plays the role of coalescing agent in the process of film formation. It is then possible to obtain DPUR which contain either cationic DPUR with a pH of less than 7 (cationic moieties are attached to the polyurethane or polyurethane-urea chain) or anionic DPUR with a pH of greater than 7 (anionic moieties are attached to the polyurethane or polyurethane-urea chain). If non ionic hydrophilic moieties are attached to or incorporated in the polyurethane or polyurethane-urea chain, then a nonionic DPUR may be obtained. 

Polyurethane emulsions and dispersions in water may also be made by incorporating polar or hydrophilic groups as described in Chapter 9. They are fully reacted, containing urethane and urea groups, are of high molecular weight, and may contain cosolvent. The chemistry of these is complex and beyond the scope of this book. They are used for the same applications as the solution polymers, and as primers for a range of plastic surfaces. 

Azo-containing polyurethane-coated drug pellets Model drugs (hydrophilic in nature) Double-coated drug pellets which are undercoated with (carboxymethyl)(ethyl)-cellulose and overcoated with the azo polymer Colon-specific delivery Effective prevention of the drug leakage was observed withPU [25]... 

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