Cationic polymers, categories

Cationic polymers can be grouped in three categories ammonium (primary, secondary, tertiary, and quaternary) sulfonium and phosphonium compounds. Of these, the ammonium-based polymers have been the most popular, because phosphonium compounds have not been synthesized to high molecular weights (2-8), and sulfonium monomers are generally unstable and less readily available than quaternary ammonium monomers (9-i2). 

Relatively short-chained cationic polymers of average molar mass and high charge density are suitable for patch flocculation. Modified polyethylene imines, polyamines, and polyamide-amine-epichlorohydrin resins are in this category. 

Linear cationic polymers represent a single chain of cationic copolymers of well-defined molecular weights. These polymers as well as their analogues of different shapes can be subdivided into various categories based upon their molecular weights, compositions and co-monomer types. 

Apart from polyplexes, various nanoscale assemblies of cationic polysaccharides are also proposed to promote the surface-mediated delivery of DNA to cells. These approaches are classified into one of two broad categories (i) methods based upon the physical adsorption of preformed polyplex on polymeric surfaces like PLGA or collagen films and these polyplex functionalized films promoted surface-mediated transfection of cells in vitro and in vivof (ii) methods for layer-by-layer adsorption of DNA and cationic polymers on surfaces to fabricate multilayered thin films. Recently, degradable carbohydrate-based nanogels were proposed for codelivery of pDNA and therapeutic proteins. These systems were designed to possess stimuli-sensitive characteristics where the temperature-sensitive property of nanogels allowed the facile encapsulation of biomaterials, while... 

Cationic polymers also exhibit DNA condensing properties similar to cationic lipids. These polymers can be divided into two categories based on their origin natural and synthetic. 

While not strictly considered emulsions, two other systems may be classified in this category, both of which comprise very small particles of silicone fluids in aqueous dispersions. The first method of preparing these microdroplets involves in situ polymerization of a water-soluble vinyl monomer or mixtures of said monomer and acryl comonomers. The silicone fluids are first dispersed into microdroplets in the water phase by means of high-speed agitation and then the vinyl monomers or cationic polymers are added at elevated temperatures in the presence of free-radical catalysts. The resulting aqueous polymer matrix contains stable, discreet microdroplets of the silicone fluids. The second method utilized to prepare such a fine dispersion is very-high-pressure injection of silicone into the aqueous phase. These microdroplets have been referred to as nanoparticles, but they are actually nanometer-sized fluid droplets as opposed to nanometer-sized sihcone resin particles, which are referred to by the same term (86). Both of the systems described above have been claimed to readily deposit onto hair and skin, and to increase ease of formulation (87,88). 

The subject of interactions between oppositely charged polymers and surfactants can be divided into two categories. One category deals with anionic polymer and cationic surfactant and the other deals with cationic polymer and anionic surfactant. The interactions are similar in principle in both the categories. 

Properties. HydroxyethjIceUulose [9004-62-0] (HEC), is a nonionic polymer. Low hydroxyethyl substitutions (MS = 0.05-0.5) yield products that are soluble only in aqueous alkali. Higher substitutions (MS > 1.5) produce water-soluble HEC. The bulk of commercial HEC falls into the latter category. Water-soluble HEC is widely used because of its broad compatibiUty with cations and the lack of a solution gel or precipitation point in water up to the boiling point. The MS of commercial HEC varies from about 1.8 to 3.5. The products are soluble in hot and cold water but insoluble in hydrocarbon solvents. HEC swells or becomes pardy to mosdy soluble in select polar solvents, usually those that are miscible with water. 

Table 7 lists in four categories some of the linear polymers which can be cross-linked to form hydrogels nonionic, anionic, cationic, and ampholytic linear poly-... 

Another troublesome borderline area is that between ionic solids and three-dimensional polymers. The distinction cannot be made from the structure alone. Electrical conductivity in the molten state does not, as already mentioned, necessarily demonstrate the presence of ions in the solid state and such a test is inapplicable where, as often happens, the substance sublimes or decomposes before melting. There can rarely be any objective means of assigning a compound to one category or the other. We are often persuaded towards one description on aesthetic grounds. For example, the structure of sodium chloride cannot easily be rendered in terms of localised, electron-pair bonds (but this is true also of many unequivocally covalent compounds). Its structure is eminently plausible for an array of cations and anions, however. 

Tens of conductive LB films have been developed so far, including metallic and superconductive LB films. These LB films are classified into the categories anion radical salt, charge-transfer complex, cation radical salt, conducting polymer, and transition metal complex in this section. The LB films, with metallic temperature dependences of conductivity, and the fullerene LB films, which exhibit a superconducting transition, are discussed separately. 

Synthetic PAs are produced by polycondensation of bifunctional monomers or by cationic and anionic ring-opening polymerization of lactams. Polymers obtained with the first technique are linear, whereas chain branching may occur with anionic polymerization. Based on their chemical structure, synthetic polyamides may be classified into two categories [1] ... 

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