Salts of acrylic or methacrylic acid

Macromonomers were prepared by polymerizing oxazolines with monofunctional initiators (e.g., methyl p-toluenosulfonate) and terminating the polymerization with salts of acrylic or methacrylic acid. Macromonomers with M varying from M — 500 to —2500 and MJM - 1.2-1.4 were obtained functionalities, however, depended strongly on reaction conditions and the values between 0.99 down to —0.5 and lower were reported [280]. 

Poly(2-alkyl oxazoline)s having methacrylate or acrylate end groups were prepared by two methods [182]. a) Living polyoxazoline chains, prepared using methyl p-toluene sulphonate as initiator, were end-capped by reaction with metal salts or tetraalkylammonium salts of acrylic or methacrylic acid or a trialky-lammonium salt or trimethylsilyl ester of methacrylic acid (functional termination). b) The living polymers were terminated with water in the presence of Na2C03 to provide hydroxyl-terminated chains. Subsequent acylation with acry-loyl or methacryloyl chloride in the presence of triethylamine led to the formation of the macromonomers. The procedures are outlined in the following Scheme 51. 

Reacting HfOCI wiilli the sodium or potassium salt of acrylic or methacrylic acid, we obtained for the first time Hf(IV)-containing monomers. Hafnium oxoacrylates and methaaylates were syn-thesized according to the Scheme 10.8 (polymer 7). 

These compounds were prepared by reacting HfOCl with the sodium or potassium salt of acrylic or methacrylic acid. The reaction mixture in methanol was stirred between 40 and 50 °C for 5 honrs. The resnlting precipitate was filtered off, washed, and dried in vacnnm. 

These componnds were prepared by reacting Cp HfCl with the potassium salt of acrylic or methacrylic acid. An excess of the salt was added to a Cp HfCl solution in benzene, and the reaction was stirred at 50 °C. The unreacted potassium methacrylate and KCl were separated by filtration. Removing benzene in vacuum, we obtained powder prodncts. 

A salt of a polymer or copolymer of acrylic or methacrylic acid, in which the acid is neutralized with alkanolamines, alkylamines, or lithium salts [677], is suitable as a dispersing agent. 

Acrylic This resin is manufactured from a copolymer of acrylic or methacrylic acid with divinylbenzene (Figure 4.10). The result is a weak acid ion-exchange resin with -COOH groups that have very little salt splitting capacity, but are very effective in removing Ca2+ and similar ions under alkaline conditions. 

Typically, carboxylate ionomers are prepared by direct copolymerization of acrylic or methacrylic acid with ethylene, styrene or similar comonomers by free radical copolymerization (65). More recently, a number of copolymerizations involving sulfonated monomers have been described. For example, Weiss et al. (66-69) prepared ionomers by a free-radical, emulsion copolymerization of sodium sulfonated styrene with butadiene or styrene. Similarly, Allen et al. (70) copolymerized n-butyl acrylate with salts of sulfonated styrene. The ionomers prepared by this route, however, were reported to be "blocky" with regard to the incorporation of the sulfonated styrene monomer. Salamone et al. (71-76) prepared ionomers based on the copolymerization of a neutral monomer, such as styrene, methyl methacrylate, or n-butyl acrylate, with a cationic-anionic monomer pair, 3-methacrylamidopropyl-trimethylammonium 2-acrylamlde-2-methylpropane sulfonate. 

Ionomers of practical interest have been prepared by two synthetic routes (a) copolymerization of a low level of functionalized monomer with an olefinically unsaturated monomer or (b) direct functionalization of a preformed polymer. Typically, carboxyl containing ionomers are obtained by direct copolymerization of acrylic or methacrylic acid with ethylene, styrene and similar comonomers by free radical copoly-merization. Rees (22) has described the preparation of a number of such copolymers. The resulting copolymer is generally available as the free acid which can be neutralized to the degree desired with metal hydroxides, acetates and similar salts. Recently, Weiss et al.(23-26) have described the preparation of sulfonated ionomers by copolymerization of sodium styrene sulfonate with butadiene or styrene. 

The last-mentioned inhibitor is of particular interest. In the acid, it obviously exists as a nonvolatile salt that can act as a still-pot inhibitor when small amounts of acrylic or methacrylic acid have to be distilled under reduced pressure to prepare an inhibitor-free sample of the acids. 

Water is the ideal solvent from the cost and pollution viewpoints, but it is a non-solvent for many surface coating polymers. It will ssolve a small number of homopolymers, notably those derived from acrylamide, acrylic acid, itaconic acid, vinyl methyl ether, vinyl pyrrolidone and vinyl sulphonic acid, but none of these homopolymers forms flexible films of use in the coatings industry. While copolymers of acrylic or methacrylic acids with acrylate esters are generally insoluble in water, their salts are soluble when the acid content is over 5% (for hydrophilic monomers) and 12% (for hydrophobic monomers). Such polymers can be prepared in solution, or in emulsion, but not in aqueous solution. This is because the acrylate esters are insoluble in water. The acid is copolymerised in the un-ionised form because the ion is unreactive to free radicals. In emulsion polymerisation, care has to be taken to avoid homopolymerisation of the acrylic or methacrylic acid in the water phase. Suppression of homopolymerisation requires a low concentration of acid throughout the polymerisation process. This can be achieved by using a long reaction period and slow addition of monomer mixture, or by careful pH buffer selection. 

Another example has been presented by Hsuie. Polyethylene films irradiated in the presence of air and stored for a couple of hours have been immersed into an aqueous solution of acrylic or methacrylic acid containing some Fe salt. In this case, the grafting process is initiated by the redox reaction between the peroxide functions and the iron salt. The grafting ratio first increases with time and then reaches a plateau when the peroxide sites have been consumed. It is an increasing function of the irradiation dose and of the monomer concentration. 

Ionomers are made in a two-stage process. In the first step, we copolymerize ethylene with small amounts of an organic acid containing a vinyl group, such as acrylic or methacrylic acid, in a high pressure reactor. In the second step, we neutralize the acid comonomers to form metal salts. We can create ionomers with a variety of metal salts, including sodium, calcium, and zinc. 

Neutralization of ethylene copolymers containing up to 5%-10% acrylic or methacrylic acid copolymer with a metal salt such as the acetate or oxide of zinc, magnesium, and barium yields products referred to as ionomers. (Commercial products may contain univalent as well as divalent metal salts.) lonomers are marked by Du Pont under the trade name Surlyn. These have interesting properties compared with the nonionized copolymer. Introduction of ions causes disordering of the semicrystalline structure, which makes the polymer transparent. lonomers act like reversibly cross-linked thermoplastics as a result of microphase separation between ionic metal carboxylate and nonpolar hydrocarbon segments. The... 

It has been shown that polymers with free phthalic acid groups dissolve much faster and at a lower pH than those esterified with acrylic or methacrylic groups. The presence of plasticizer and the nature of the salts in the dissolution medium influence the dissolution rate [62],... 

Weak Acid Cation Exchangers, The synthesis of weak acid cation exchangers is a one-step process when acrylic acid or methacrylic acid is copolymerized with DVB. If an acrylic ester is used as the monomer instead of an acrylic acid, the ester groups must be hydrolyzed after polymerization using either an acid or base (NaOH) to give the carboxylic acid functionality, or the sodium salt (4) of it. 

The preparation of ionomers involves either the copolymerization of a functionalized monomer with an olefinic unsaturated monomer or direct functionalization of a preformed polymer. Typically, free-radical copolymerization of ethylene, styrene, or other a-olefins with acrylic acid or methacrylic acid results in carboxyl-containing ionomers. The copolymer, available as a free acid, is then neutralized partially to a desired degree with metal hydroxides, acetates, or similar salts. The second route for the preparation of ionomers involves modification of a preformed polymer. For example, sulfonated polystyrene is obtained by direct sulfonation of polystyrene in a homogeneous solution followed by neutralization of the acid to the desired level. Some commercially available ionomers are listed in Table 15.17. 

---