Radical polymerization of acrylic acid

Ladaviere C, Dorr N, Claverie IP (2001) Controlled radical polymerization of acrylic acid in protic media. Macromolecules 34 5370-5372... 

Couvreur L, Lefay C, Belleney 1 (2003) First nitroxide-mediated controlled free-radical polymerization of acrylic acid. Macromolecules 36 8260-8267... 

These superabsorbents are synthesized via free radical polymerization of acrylic acid or its salts in presence of a crosslinker (crosslinking copolymerization). Initiators are commonly used, water-soluble compounds (e.g., peroxodi-sulfates, redox systems). As crosslinking comonomers bis-methacrylates or N,hT-methylenebis-(acrylamide) are mostly applied. The copolymerization can be carried out in aqueous solution (see Example 5-11 or as dispersion of aqueous drops in a hydrocarbon (inverse emulsion polymerization, see Sect. 2.2.4.2). 

As a comparison and reproduction to recent works done by DeSimone and coworkers [2], attempts were made in the free radical polymerization of acrylic acid (AA) in supercritical carbon dioxide (SCCO2) with Azoisobutyronitrile (AIBN) as initiator. 

Kabanov et al. have studied the radical polymerization of acrylic acid in aqueous solutions [61] (see Chap. 4, Sect. 1.4). A crystaline, syndiotactic polymer was formed at pH 10.2-10.8. The kinetics of the photosensitized polymerization of acrylic acid was studied by Galperina et. al. [62], They observed a strong solvent dependence for the rate constant of propagation. At 293 K, kp[mol-1 dm3 s-1] = 22 500 in water, 4 200 in formamide, and 500 in dimethylsulphoxide. 

The concept of controlled hydrolytic stability based on substituted phospha-zenes can be extended to organic polymers. Free radical polymerization of acrylic acid in aqueous solution in presence of 39 yields a degradable hydrogel with imidazolyl groups as controlling sites with respect to the hydrolytic stability. ... 

Wittenberg, N. F. G. (2013). Kinetics and modeling of the radical polymerization of acrylic acid and of methacrylic acid in aqueous solution. Georg-August-Universitat Gottingen. 

Bolshakov et al. described low-temperature (100-130 K) polymerizations of acrylic acid, acrylamide, and methyl acrylate, in which radical mobility was strongly hindered by their specific interactions with the molecules of a melting alcohol matrix [50]. 

Resins with good hydrodynamic properties and sorption capadties for proteins and enzymes have been prepared by the polymerization of acrylic acid or methacrylic acid and a crosslinking monomer such as 1,3,5-triacryloylhexahydrotriazine (TAT) in aqueous acetic acid using a radical initiator. Methacrylic add-TAT copolymer prqjared by using a redox catalyst is useful as a cation-exchange resin for selective and reversible sorption of proteolytic enzymes such as terrilytin. 

The polystyrene obtained by living cationic polymerization with R—Cl/Lewis acid possesses a carbon-chlorine terminal that is subsequently used for the living radical polymerizations of acrylates and methacrylates to give block copolymers such as B-65 to B-67 376-378... 

In addition to catalysis of small molecule transformations and biocatalysis, non-functionalized LLC phases used as reaction media have also been found to accelerate polymerization reactions as well. For example, the L and Hi phases of the sodium dodecylsulfate/n-pentanol/sulfuric acid system have been found to lower the electric potential needed to electropolymerize aniline to form the conducting polymer, polyaniline [110]. In this system, it was also found that the catalytic efficiency of the L phase was superior to that of the Hi phase. In addition to this work, the Ii, Hi, Qi, and L phases of non-charged Brij surfactants (i.e., oligo(ethylene oxide)-alkyl ether surfactants) have been observed to accelerate the rate of photo-initiated radical polymerization of acrylate monomers dissolved in the hydrophobic domains [111, 112]. The extent of polymerization rate acceleration was found to depend on the geometry of the LLC phase in these systems. Collectively, this body of work on catalysis with non-functionalized LLC phases indicates that LLC phase geometry and system composition have a large influence on reaction rate. 

Polyamic acids are useful resists especially when containing 2,2 -dinitrodi-phenylmethane segments, while a Ti sapphire laser has been found to be effective for 3D curing and microfabrication. On a theoretical note, a direct correlation has been found between the calculated Boltzmann-averaged dipole moment and the measured maximum rate of photoinitiated radical polymerization of acrylic monomers. ... 

In the same line, high-Pressure carbon monoxide (HiPco) SWCNTs were functionalized along their sidewalls with hydroxyalkyl groups using a radical addition scheme.These moieties were found to be active in the polymerization of acrylic acid from the surface of the nanotubes by a redox radical mechanism. In Figure 9.4 (left-hand panel) the Raman response of pristine, ethanol-treated and polymer-modified samples is illustrated. Compared with... 

Solvents influence the rate of free-radical homopolymerization of acrylic acid and its copolymerization with other monomers. Hydrogen-bonding solvents slow down the reaction rates. Due to the electron-withdrawing nature of the ester groups, acrylic and methacrylic ester polymerize by anionic but not by cationic mechanisms. Lithium alkyls are very effective initiators of a-methyl methacrylate polymerization yielding stereospecific polymers.Isotactic poly(methyl methacrylate) forms in hydrocarbon solvents. Block copolymers of isotactic and syndiotactic poly(methyl methacrylate) form in solvents of medium polarity. Syndiotactic polymers form in polar solvents, like ethylene glycol dimethyl ether, or pyridine. This solvent influence is related to Lewis basicity in the following order ... 

Basic acrylate chemistry. The basic acrylic monomers or oligomers contain unsaturated double bonds (vinyl groups), and consequently cure by addition polymerization involving a free-radical reaction. Free-radical-producing compounds such as peroxides, peracetic acids, and sulfones are added to acrylic resins to initiate polymerization. Free-radical polymerization of acrylics may also be induced by exposure to U V or visible light. These UV-curing adhesives, most of which are based on acrylic or modified acrylic... 

Example 6.4 Synthesis of a Bicomponent Polymer Network Through a Radical Polymerization of Methacrylic Acid 2-Ethoxyethyl Ester and b s(Acrylate)... 

Another example is the polymerization of acrylic acid in supercritical carbon dioxide (20 wt %) with t-butyl hydroperoxide as initiator [24]. The effect of initiator concentration (2 to 6%), temperature (160 to 350 °C) and pressure (185 to 320 bar) have been reported. The polymerization was conducted at 250 °C and 310 bar. Contrary to conventional free radical polymerizations, in these polymerizations, it is reported that the initiator amount does not influence the molecular weight, even though in the absence of the initiator polymerization would not proceed. No explanation for this observation has been provided. Also, at a given temperature, molecular weight was found to decrease with pressure. For example, at 160 °C weight average molecular weight decreased from about 80,000 to 45,000 upon increase of the pressure from 185 to 250 bar while polydispersity was reduced from about 10 to 7. This behavior is somewhat similar to the... 

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