Sodium-3 -acrylamido-3 -methylbutanoate

Associative copolymers of acrylamide with N-alkylacrylamides, terpoly-mers of acrylamide, N-decylacrylamide, and sodium-2-acrylamido-2-methyl-propane sulfonate (NaAMPS), sodium acrylate (NaA), or sodium-3-acrylamido-3-methylbutanoate (NaAMB) have been shown to possess the required rheologic behavior to be suitable for enhanced oil-recovery processes [1184]. 

Sodium 12-b u toxydodecyl sulfate surface tension, 8 2441 Sodium 2-acrylamido-2-methylpropane-sulfonate (AMPS), 20 487 Sodium 3-acrylamido-3-methylbutanoate (AMBA), 20 487... 

The copolymers of acrylamide with sodium-3-acrylamido-3-methylbutanoate (NaAMB), as well as the homopolymer of NaAMB, were prepared in aqueous solution at 30 C using 0.1 mole percent potassium persulfate as the initiator. The feed ratio of AM NaAMB was varied from 95 5 to 25 75, and the total monomer concentration was held constant at 0.456 M. Following reaction, the polymers were purified by precipitation in acetone, dialysis, and lyophilization. Conversions were determined gravimetricallv and compositions were determined using elemental analysis and NMR. ... 

Copolymers of acrylamide (AM) with sodium-3-acrylamidO 3 methylbutanoate have been prepared with a range of compositions yet similar molecular weights (Table 1) in order to assess the effect of microstructure on solution properties. Particular attention has been focused on statistical monomer sequence lengths along the polymer backbone as calculated from experimental reactivity ratios (rj xr2 = 0.56) for the monomer pair . 

Fig. 1. Temperature of phase separation versus weight % calcium chloride for the homopolymer of sodium 3-acrylamido-3-methylbutanoate (AMB). (Polymer concentration = 1.5 grams/dL).

Synthesis. Polyampholytes are most readily prepared by the direct statistical copolymerization of anionic and cationic monomers typically in aqueous media, via conventional free radical pol3unerization. Examples of such materials were first reported in the 1950s (240-244). Using this approach a wide range of copolymers and terpolymers, often with a neutral hydrophilic monomer such as acrylamide, have been reported. For example, early reports of statistical polyampholytes include the methacrylic acid-stat-2-(dimethylamino)ethyl methacrylate copolymers (245), from IZ and 2Z with 6Z and the iV,A(-diethylallylamine-stat-acrylic acid copolymers from IZ and 6Z (246). More recently, synthesis and properties of novel polyampholytic terpol5uners have been described (247-250). For example, the aqueous solution properties of novel ampholytic terpolymers of acrylamide, sodium 3-acrylamido-3-methylbutanoate 5Z and 3-(acrylamidopropyl)trimethylammonium chloride 8Z have been studied in detail (187). 

Similarly, such AB diblocks may be prepared based on the acrylamido family of monomers. For example, the synthesis of novel AB diblock copolymers comprised of the two anionic monomers sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) and sodium 3-acrylamido-3-methylbutanoate (AMBA) have been reported (42,44). By analogy with the styrenic block copolymers, these AMPS-AMBA species also exhibit reversible pH-induced self-assembly by virtue of the fact that the AMBA residues may be reversible protonated, switching the residues from a hydrophilic (high pH) to a hydrophobic (low pH) state. Similar AB diblocks of AMPS with sodium 6-acrylamidohexanoate which also exhibit pH-induced micellization have been reported by Yusa and co-workers (45) RAFT has... 

PoIy(acrylamide-co-sodium-3-acrylamide-3-methylbutanoate-co-(2-(acrylamido)-2-methylpropyl) trimethylammonium chloride)... 

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