Cationic water-soluble homopolymers

X HE PRODUCTION OF CATIONIC WATER-SOLUBLE HOMOPOLYMERS and CO-polymers with acrylamide has grown rapidly in recent years (i) because of their diverse commercial applications. These polymers are used for fines retention in paper making, as flocculants and biocides in waste water treatment, as stabilizers for emulsion polymerization, in cosmetics and phar-... 

Imazato and co-workers [29,30] prepared a novel monomer, methacryloyloxydodecyl pyrimidinium bromide (MDPB). A water-soluble homopolymer of MDPB and copolymer of MDPB with acrylamide were also synthesised and the bactericidal activity against oral streptococci was studied. The mechanism of action of these quaternary compounds is assumed to be due to direct cationic binding to cell wall components, which results in disruption of the cell wall membrane, and subsequently results in leakage of critical cell contents and cell death. 

A similar approach has been also used for the synthesis of covalently linked DHBCs. Polysaccharide based DHBCs were prepared by end-to-end eoupling of two readily available biocompatible water-soluble homopolymers [35]. The synthesis was a two step reaction where a) a terminal aldehyde group of a dextran homopolymer was oxidized and b) a monoamine end functionalized PEG reaeted with the oxidized dextran, via a lactone aminolysis reaction. Interestingly, the obtained polymer could be chemically modified, in a controlled way, in order to produce neutral-cationic or neutral-anionic DHBCs. 

To synthesize water-soluble or swellable copolymers, inverse heterophase polymerization processes are of special interest. The inverse macroemulsion polymerization is only reported for the copolymerization of two hydrophilic monomers. Hernandez-Barajas and Hunkeler [62] investigated the copolymerization of AAm with quaternary ammonium cationic monomers in the presence of block copoly-meric surfactants by batch and semi-batch inverse emulsion copolymerization. Glukhikh et al. [63] reported the copolymerization of AAm and methacrylic acid using an inverse emulsion system. Amphiphilic copolymers from inverse systems are also successfully obtained in microemulsion polymerization. For example, Vaskova et al. [64-66] copolymerized the hydrophilic AAm with more hydrophobic methyl methacrylate (MMA) or styrene in a water-in-oil microemulsion initiated by radical initiators with different solubilities in water. However, not only copolymer, but also homopolymer was formed. The total conversion of MMA was rather limited (<10%) and the composition of the copolymer was almost independent of the comonomer ratio. This was probably due to a constant molar ratio of the monomers in the water phase or at the interface as the possible locus of polymerization. Also, in the case of styrene copolymerizing with AAm, the molar fraction of AAm in homopolymer compared to copolymer is about 45-55 wt% [67], which is still too high for a meaningful technical application. 

We note from these arguments that ionic surfactants would be expected to interact broadly with different types of water-soluble polymers. This is true, in particular, for anionics the considerably weaker interaction of cationics is not well understood. Nonionic surfactants, on the other hand, should have little tendency to interact with hydrophilic homopolymers since no further stabilization of the micelles can be expected we noted above that nonionic surfactants only exceptionally associate to... 

Different norbornenes and 7-oxanorbornenes were dispersed in water using cationic surfactants, yielding homopolymers and block-copolymers with narrow molecular weight distribution (PDI<1.20). It was concluded that the ROMP of these slightly water soluble monomers is living. 

Cationic polymers include homopolymers and cationic copolymers obtained by the polymerization of a vinylic monomer with a quaternary ammonium group or a quatemized amine with another soluble monomer in water such as acrylamide and methacrylamide. The most frequently used polymers are those derived from gum guar such as guar hydroxyl propyl triamonium chloride. They are sold under the trade names Jaguar C13S, C17, etc. [12-16]. 

A/ -Vinylformamide (NVF), a reactive functional monomer with novel physical and chemical properties and favorable toxicology (1,2) has shown significant promise in a number of application areas. It is highly reactive under free radical or cationic reaction conditions. The free radically prepared homopolymer is readily water soluble and can be hydrolyzed in a controllable fashion to give cationic or free base amine functional polymers. NVF, like other vinylamides, also copolymerizes well with most commercially available monomers, especially vinyl acetate, acrylamides, and acrylates (2). NVF s moderate toxicity enables the material to be used in applications where there is some possibility of worker exposure. However, it is difficult to obtain with NVF alone the broad range of physical and chemical properties needed for many applications requiring different glass transition temperatures and variable hydrophilic and hydrophobic characteristics. Also, there are situations where the toxicity profile of the monomer system is a primary concern and NVF may not be considered adequately safe. 

The notion of a polyelectrolyte complex is well established for the mixture of two homopolymers one anionic, the other cationic. The complex formation is generally associated with a phase separation (often a precipitation) although water soluble polymeric complexes are known. Only few data are available when the charge density of the polyelectrolytes is progressively decreased. This situation is exemplified with a series of mixtures of polyacrylamide derivatives, one family of copolymers has various contents in anionic units, the other is similar but with cationic units. We found that even for a few percent in ionic units, the mixtures water/copolymer anionic/copolymer cationic phase separates a polymer rich phase (including the two types of copolymers) is in equilibrium with a very diluted polymer solution. 

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