Aqueous acrylic acid

Barone, G., Crescenzi, V., Liquori, A.M., Quadrifoglio, F. (1967) Solubilization of polycyclic aromatic hydrocarbons in poly(meth-acrylic acid) aqueous solutions. J. Phys. Chem. 71, 2341-2345. 

Y. Zhou, D. Yang, J. Nie, Electrospinning of chitosan/poly(vinyl alcohol)/acrylic acid aqueous solutions, J. Appl. Polym. Sci. 102 (2006) 5692-5697. 

Cupric chloride and ferrous ammonium sulfate were then successfully used as inorganic inhibitors to prevent homopolymerization in the liquid phase. Films were sealed in 50% acrylic acid aqueous solution saturated with the inorganic inhibitor under nitrogen gas and irradiated with y-rays at a dose rate of 0.13 Mrad/hr at room temperatures. After irradiation, the films were washed with water. The results are presented in Figure 6. The weight increase varied linearly with dose. The rate of grafting with ferrous ammonium sulfate was higher than that with cupric chloride. 

Fig 6. Graftings of acrylic acid to dense polyvinyl chloride film in 50% acrylic acid aqueous solution saturated with cupric chloride (O) and ferrous ammonium sulfate (A)- Dose rate 0.13 Mrads per hr. 

Peng F, Li GZ, Liu XX, Wu SZ, Tong Z (2008) Redox-responsive gel-sol/sol-gel transition in poly(acrylic acid) aqueous solutimi containing Fe(ni) ions switched by light. J Am Chem Soc 130 16166-16167... 

He S, Ren B, Liu X, Tong Z (2010) Reversible electrogelation in poly(acrylic acid) aqueous solutions triggered by redox reactions of counterions. Macromol Chem Phys 211 2497-2502... 

Apart from the thoroughly studied aqueous Diels-Alder reaction, a limited number of other transformations have been reported to benefit considerably from the use of water. These include the aldol condensation , the benzoin condensation , the Baylis-Hillman reaction (tertiary-amine catalysed coupling of aldehydes with acrylic acid derivatives) and pericyclic reactions like the 1,3-dipolar cycloaddition and the Qaisen rearrangement (see below). These reactions have one thing in common a negative volume of activation. This observation has tempted many authors to propose hydrophobic effects as primary cause of ftie observed rate enhancements. 

As an application of this nucleophilic reactivity, 2-aminothiazole was used to partially convert into amide the polymer obtained from acrylic acid, benzene, and acetic anhydride (271). An aqueous medium is reported to favor the reaction between acetic anhydride and 2-aminothiazole (272). 

Poly(acrylic acid) and Poly(methacrylic acid). Poly(acryHc acid) (8) (PAA) may be prepared by polymerization of the monomer with conventional free-radical initiators using the monomer either undiluted (36) (with cross-linker for superadsorber appHcations) or in aqueous solution. Photochemical polymerization (sensitized by benzoin) of methyl acrylate in ethanol solution at —78° C provides a syndiotactic form (37) that can be hydrolyzed to syndiotactic PAA. From academic studies, alkaline hydrolysis of the methyl ester requires a lower time than acid hydrolysis of the polymeric ester, and can lead to oxidative degradation of the polymer (38). Po1y(meth acrylic acid) (PMAA) (9) is prepared only by the direct polymerization of the acid monomer it is not readily obtained by the hydrolysis of methyl methacrylate. 

Functional derivatives of polyethylene, particularly poly(vinyl alcohol) and poly(acryLic acid) and derivatives, have received attention because of their water-solubility and disposal iato the aqueous environment. Poly(vinyl alcohol) is used ia a wide variety of appHcations, including textiles, paper, plastic films, etc, and poly(acryLic acid) is widely used ia detergents as a builder, a super-absorbent for diapers and feminine hygiene products, for water treatment, ia thickeners, as pigment dispersant, etc (see Vinyl polymers, vinyl alcohol polymers). 

Polycarboxylate Cements. Polycarboxylate cements (30,31) are made by mixing a 2inc oxide-based powder and an aqueous solution of poly(acryHc acid) [9003-01 ] or similar polyacid (see Acrylic acid). The biological effects of these cements on soft and minerali2ed tissues are mild (32). 

Acrylic acid [79-10-7] M 72.1, m 13°, b 30°/3mm, d 1.051, pK 4.25. Can be purified by steam distn, or vacuum distn through a column packed with copper gauze to inhibit polymerisation. (This treatment also removes inhibitors such as methylene blue that may be present.) Azeotropic distn of the water with benzene converts aqueous acrylic acid to the anhydrous material. 

This reaction is utilized by Burrows et al. [70] to photoinitiate grafting of acrylamide, acrylic acid, methacrylamide, and acrylonitrile on cellulose triacetate in acidic aqueous solution. 

Fig. 15. Energy of proton dissociation (Ez) from Z times ionized polyelectrolyte molecules as function of the degree of dissociation (a). (A) - PPAL (1), PPAS (2), PPA (3), polyfmethacrylic acid) (4), copolymer of acrylic acid with ethylenesulfonic acid (50 50) in aqueous solutions (5), (B) - PPAL (1), PPAS (2), PPA in the presence of NaCl (3) ( ) INaClj = 0 (X) fNaCll = 0.25 mmol/1 (o) 0.50 mmol/1...

A modified latex composition contains a phosphorus surface group. Such a latex is formed by emulsion polymerization of unsaturated synthetic monomers in the presence of a phosponate or a phosphate which is intimately bound to the surface of the latex. Thus, a modified latex containing 46% solids was prepared by emulsion polymerization of butadiene, styrene, acrylic acid-styrene seed latex, and a phosphonate comonomer in H20 in the presence of phosphated alkylphenol ethoxylate at 90°C. The modified latex is useful as a coating for substrates and as a binder in aqueous systems containing inorganic fillers employed in paper coatings, carpet backings, and wallboards [119]. 

Aqueous, removable, pressure-sensitive adhesive compositions, useful for high-performance applications, comprise a mixture of a copolymer of alkyl (meth)acrylate and N-substituted (poly)amide of (meth)acrylic acid and a copolymer of alkyl (meth)acrylate and ethylenically unsaturated carboxylic acid, where at least one of the copolymers is an emulsion copolymer. Polyoxyalkyl-enes and phosphate esters may be used as surfactants [234]. 

Other uses of thickening agents include pharmaceutical preparations, paper production, and oil well drilling fluids. This latter use is necessary because oil is obtained from rock that is porous. In order to remove the oil without altering the mechanical properties of the porous rock, viscous liquids ( drilling fluids ) are pumped into the rock to replace the oil. Among the substances that can be used for this purpose are thickened aqueous solutions of polymers such as poly(acrylic acid) or poly(acrylonitrile). 

With regard to the composition of the electrical effects, values of pj for the sets studied are reported in Table XIV. The sets in which the hydroxyl group is the reaction site generally exhibit a Pr value of about 39. The cis-3-substituted acrylic acids show a p value of 39 in aqueous solution. The value of 71 obtained in 50% aqueous ethanol seems too large. 

This concept covers most situations in the theory of AB cements. Cements based on aqueous solutions of phosphoric acid and poly(acrylic acid), and non-aqueous cements based on eugenol, alike fall within this definition. However, the theory does not, unfortunately, recognize salt formation as a criterion of an acid-base reaction, and the matrices of AB cements are conveniently described as salts. It is also uncertain whether it covers the metal oxide/metal halide or sulphate cements. Bare cations are not recognized as acids in the Bronsted-Lowry theory, but hydrated... 

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 conformations adopted by polyelectrolytes under different conditions in aqueous solution have been the subject of much study. It is known, for example, that at low charge densities or at high ionic strengths polyelectrolytes have more or less randomly coiled conformations. As neutralization proceeds, with concomitant increase in charge density, so the polyelectrolyte chain uncoils due to electrostatic repulsion. Eventually at full neutralization such molecules have conformations that are essentially rod-like (Kitano et al., 1980). This rod-like conformation for poly(acrylic acid) neutralized with sodium hydroxide in aqueous solution is not due to an increase in stiffness of the polymer, but to an increase in the so-called excluded volume, i.e. that region around an individual polymer molecule that cannot be entered by another molecule. The excluded volume itself increases due to an increase in electrostatic charge density (Kitano et al., 1980). 

This is a reasonable inference, because site binding is significant only with multivalent cations and strong electrostatic interactions. Under these conditions ion polarization occurs and bonds have some covalent character (Cotton Wilkinson, 1966). This is illustrated by the data of Gregor, Luttinger Loebl (1955a,b). They measured the complexation constants of poly(acrylic acid), 0 06 n in aqueous solution, with various divalent metals, which, as it so happens, are of interest to AB cements (Table 4.1). The order of stability was found to be... 

Crisp, S., Prosser, H. J. Wilson, A. D. (1976). An infra-red spectroscopic study of cement formation between metal oxides and aqueous solutions of poly(acrylic acid). Journal of Materials Science, 11, 36-48. 

Rymden, R. Stilbs, P. (1985a). Counterion self-diffusion in aqueous solutions of poly(acrylic acid) and poly(methacrylic acid). Journal of Physical Chemistry, 89, 2425-8. 

The polyelectrolyte cements are modern materials that have adhesive properties and are formed by the cement-forming reaction between a poly(alkenoic acid), typically poly(acrylic acid), PAA, in concentrated aqueous solution, and a cation-releasing base. The base may be a metal oxide, in particular zinc oxide, a silicate mineral or an aluminosilicate glass. The presence of a polyacid in these cements gives them the valuable property of adhesion. The structures of some poly(alkenoic acid)s are shown in Figure 5.1. 

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. 

The poly(alkenoic acid)s used in glass polyalkenoate cement are generally similar to those used in zinc polycarboxylate cements. They are homopolymers of acrylic acid and its copolymers with itaconic add, maleic add and other monomers e.g. 3-butene 1,2,3-tricarboxylic add. They have already been described in Section 5.3. The poly(acrylic add) is not always contained in the liquid. Sometimes the dry add is blended with glass powder and the cement is activated by mixing with water or an aqueous solution of tartaric add (McLean, Wilson Prosser, 1984 Prosser et al., 1984). 

Good bonding was obtained to several substrates under aqueous conditions. Values obtained were 41 to 10-3 MPa to composite resins, and 9-8 to 15-6 MPa to stainless steel (Table 9.6). They were also reported as adhering to porcelain. No adhesion was obtained to untreated dentine or enamel. The cements could be bonded to enamel etched with add (3-5 MPa) and to dentine conditioned with poly(acrylic acid) (10 MPa). 

NMR spectroscopy of various nuclei has been used in the study of AB cements derived from various acids, including phosphoric acid and poly(acrylic acid). For example, NMR has been used in studies of dental silicate cement, i.e. the AB cement made from aqueous phosphoric add and powdered aluminosilicate glass (Wilson, 1978). In this cement, the... 

During a polymerisation operation of acryl acid in aqueous solution, in the presence of a primer and a moderator, the pump broke down and caused monomer to accumulate. Its polymerisation could not be controlled and the apparatus are destroyed. 

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