Polymerization polycarboxylates

Polymeric polycarboxylates, such as polyacrylates and acrylate-maleate copolymers, are finding usage as cobuilders in zeolite-carbonate builder systems. Polymers are finding increasing application in detergent formulations as dispersing... 

Cobalt in Catalysis. Over 40% of the cobalt in nonmetaUic appHcations is used in catalysis. About 80% of those catalysts are employed in three areas (/) hydrotreating/desulfurization in combination with molybdenum for the oil and gas industry (see Sulfurremoval and recovery) (2) homogeneous catalysts used in the production of terphthaUc acid or dimethylterphthalate (see Phthalic acid and otherbenzene polycarboxylic acids) and (i) the high pressure oxo process for the production of aldehydes (qv) and alcohols (see Alcohols, higher aliphatic Alcohols, polyhydric). There are also several smaller scale uses of cobalt as oxidation and polymerization catalysts (44—46). 

The diacids are characterized by two carboxyHc acid groups attached to a linear or branched hydrocarbon chain. AUphatic, linear dicarboxyhc acids of the general formula HOOC(CH2) COOH, and branched dicarboxyhc acids are the subject of this article. The more common aUphatic diacids (oxaUc, malonic, succinic, and adipic) as weU as the common unsaturated diacids (maleic acid, fumaric acid), the dimer acids (qv), and the aromatic diacids (phthaUc acids) are not discussed here (see Adipic acid Maleic anhydride, maleic acid, and fumaric acid Malonic acid and derivatives Oxalic acid Phthalic acid and OTHERBENZENE-POLYCARBOXYLIC ACIDS SucciNic ACID AND SUCCINIC ANHYDRIDE). The bihinctionahty of the diacids makes them versatile materials, ideally suited for a variety of condensation polymerization reactions. Several diacids are commercially important chemicals that are produced in multimillion kg quantities and find appHcation in a myriad of uses. 

AB cements are not only formulated from relatively small ions with well defined hydration numbers. They may also be prepared from macromolecules which dissolve in water to give multiply charged species known as polyelectrolytes. Cements which fall into this category are the zinc polycarboxylates and the glass-ionomers, the polyelectrolytes being poly(acrylic acid) or acrylic add copolymers. The interaction of such polymers is a complicated topic, and one which is of wide importance to a number of scientific disciplines. Molyneux (1975) has highlighted the fact that these substances form the focal point of three complex and contentious territories of sdence , namely aqueous systems, ionic systems and polymeric systems. 

The most common poly(alkenoic acid) used in polyalkenoate, ionomer or polycarboxylate cements is poly(acrylic acid), PAA. In addition, copolymers of acrylic acid with other alkenoic acids - maleic and itaconic and 3-butene 1,2,3-tricarboxylic acid - may be employed (Crisp Wilson, 1974c, 1977 Crisp et al, 1980). These polyacids are prepared by free-radical polymerization in aqueous solution using ammonium persulphate as the initiator and propan-2-ol (isopropyl alcohol) as the chain transfer agent (Smith, 1969). The concentration of poly(alkenoic add) is kept below 25 % to avoid the danger of explosion. After polymerization the solution is concentrated to 40-50 % for use. 

Humic substances. Analogous to the reactions described above, humic substances (the polymeric pigments from soil (humus) and marine sediments) can be formed by both enzymatic and non-enzymatic browning. High concentrations of free calcium and phosphate ions and supersaturation with respect to hydroxyapatite can sustain in soil, because adsorption of humic acids to mineral surfaces inhibits crystal growth (Inskeep and Silvertooth, 1988). A similar adsorption to tooth mineral in a caries lesion can be anticipated for polycarboxylic polymers from either the Maillard reaction or enzymatic browning. 

Water-soluble biodegradable polycarboxylates with an acetal or ketal weak link were inventions of Monsanto scientists in the course of their search for biodegradable deteigent polymers. However, the polymers were prevented by economics from reaching commercial status. The polymers are based on the anionic or cationic polymerization of glyoxylic esters at low temperature (molecular weight is inversely proportional to the polymerization temperature) and subsequent hydrolysis to the salt form of the polyacid, which is a hemiacetal (R = H) or ketal (R = CH3) if methylglyoxylic acid is used, and stable under basic conditions. 

Reichert and Mathias prepared related branched aramids, to those of Kim,t5-34] from 3,5-dibromoaniline (23) under Pd-catalyzed carbonylation conditions (Scheme 6.7). These brominated hyperbranched materials (24) were insoluble in solvents such as DMF, DMAc, and NMP, in contrast to the polyamine and polycarboxylic acid terminated polymers that Kim synthesized, which were soluble. This supports the observation that surface functionality plays a major role in determining the physical properties of hyperbranched and dendritic macromolecules J4,36 A high degree of cross-linking could also significantly effect solubility. When a four-directional core was incorporated into the polymerization via tetrakis(4-iodophenyl)adamantanc,1371 the resultant hyperbranched polybromide (e.g., 25) possessed enhanced solubility in the above solvents, possibly as a result of the disruption of crystallinity and increased porosity. 

These are mainly polymeric cements formed by bonding of polyions (or macroions)which are anions with small cations called counterions. Good examples are polycarboxylate cements [9], glass-ionomer cement [10], and polyphosphonic cements [11,12]. Zinc polycarboxylate, glass polyalkenoate, and resin glass polyalkenoate are some examples... 

Therefore, RE(III)-polycarboxylic acid complexes can be considered as polymeric structures made by edge-sharing rare earth-oxygen polyhedra REOm (m = l- 0) linked together by carbon chains [71],... 

Polyesters. Polyesters are polymers obtained by reacting monomeric polycarboxylic acid and polyalcohols. They are practically free of fatty acids (oils) and have a much simpler structure than that of alkyd. Polyester resins do not undergo oxidative polymerization (curing) and have a different curing mechanism than an alkyd. 

At the same time, the industry embarked on an intensive search for phosphate substitutes. Of a very large number of experimental organic builders, a few substances reached commercialization or near-commercialization, including trisodium nitrilotriaceate (NTA), trisodium carboxymethoxysuccinate (CMOS) (181) and trisodium carboxymethyltartronate (182). As discussed above, sodium citrate ether carboxylates have achieved widespread use as phosphate substitutes. Polymeric builders (polyelectrolytes) proved to be effective calcium sequestrants, but failed to satisfy the criterion of acceptable biodegradability. Interestingly, some monomeric polycarboxylates proved to be even more powerful calcium sequestrants than sodium tripolyphosphate but were not sufficiently biodegradable (183). 

Catalysts are also required in many stepwise polymerizations. For example, reaction of polycarboxylic acids and polyols (Reaction 7) is catalyzed by acids ester interchange, by metal compounds such as titanium alkoxides. On the other hand, polyurea synthesis (Reaction 6) generally does not require a catalyst. Metallic compounds are also useful in oxidative polymerization of phenols to give poly(phenylene oxides), illustrated in Reaction 14. 

Even when the charging effect is considered, the pKa of soil organic matter, unlike the pKa of a monoprotic add, tends to decrease as the ionic strength (salt concentration) of the soil solution is increased. This means that soil organic matter seems to be more acidic in more concentrated salt solutions. Synthetic polycarboxylic adds also show this behavior. It becomes clear that the application of solution concepts such as pK to complex charged polymeric solids has numerous pitfalls. 

The concept of polymeric soil release agents has been around for well over 25 years. The initial polymer chemistries (polyethylene terephthalate-polyoxyethylene terephthalate, PET-POET) were designed to deposit on fabrics and facilitate oily soil removal upon subsequent washing [98,133,134], The limitation of this chemistry was its effectiveness on synthetics (polyester) alone, with limited benefits being observed on cotton and synthetic blends. In recent years the focus has shifted to delivering soil release on cotton. Two classes of polymer chemistries have been disclosed in the recent patent literature for cotton soil release one based on hydrophobically modified polycarboxylates derived from acrylic acid and hydrophobic comonomers at defined molar ratios [188] and the other based on modified polyamines [189-193],... 

The resin can be produced using a wide range of polycarboxylic acids and polyhydric alcohol by polycondensation. Immediately before use, it is mixed with aggregates and water. When the catalyst is activated by the addition of the water, polymerization and cement hydration occur simultaneously. The optimum water-cement ratio is about 22%. The aggregate content can be selected depending on the application. 

Further investigations carried out by Chelushkin et al. [73] for various combinations of micelles formed in aqueous media by ionic amphiphilic diblock copolymers [PS-fc-P4VPQ, poly(styrene)-fetocA -poly(sodium acrylate) (PS- -PANa), and PS- -PMANa)] with oppositely charged linear PEs (polycarboxylates, polysulfonates, polyphosphates, and aromatic, aliphatic, and alicyclic quaternized polyamines) have demonstrated that the solubility of IPECs is decisively determined by (1) the aggregation state of the excess polymeric component (micelles versus individual polymeric coils) and (2) the procedure or method employed for the preparation of such macromolecular co-assemblies. 

Polycarboxylates Carboxylate derivatives of poly(vinyl alcohol) are biodegradable and functional in detergents as co-builders, although too costly to be practical replacements for polyacrylic acid at this time. Matsumura et al. polymerized vinyloxyacetic acid [69, 70] and Lever has patented polymers based on vinyl carbamates obtained from the reaction of vinyl chloroformates and amino acids such as aspartic and glutamic acids [71]. Both hydrolyze (Scheme 4), to polyvinyl alcohol, which is biodegradable. 

Other grafts to natural materials are exemplified by Dordick s work [173] in which he produced polyesters from sugars and polycarboxylates by enzyme catalysis of the condensation polymerization. These polymers and the method of synthesis may well be the future of renewable resource chemistry. 

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