Block copolymers of acrylamide

Acrylamide copolymers designed to reduce undesired amide group hydrolysis, increase thermal stability, and improve solubility in saline media have been studied for EOR appHcations (121—128). These polymers stiH tend to be shear sensitive. Most copolymers evaluated for EOR have been random copolymers. However, block copolymers of acrylamide and AMPS also have utiHty (129). 

Acrylamide copolymers designed to reduce undesired amide group hydrolysis, increase thermal stability, and improve solubility in saline media have been synthesized and studied for EOR applications. These polymers still tend to be shear sensitive. Acrylamide comonomers that have been used include 2-acrylamido-2-methylpropane sulfonate, abbreviated AMPS, (1,321-324), 2-sulfo-ethylmethacrylate (325,326), diacetone acrylamide (324, 326), and vinylpyrrolidinone (327,328). Acrylamide terpolymers include those with sodium acrylate and acrylamido-N-dodecyl-N-butyl sulfonate (329), with AMPS and N,N-dimethylacrylamide (330), with AMPS and N-vinylpyrrolidinone (331), and with sodium acrylate and sodium methacrylate (332). While most copolymers tested have been random copolymers, block copolymers of acrylamide and AMPS also have utility in this application (333). 

Fig. 2 Response of various PECs (first polyelectrolytes in initial solutions) to subsequent addition of salt a particle mass Mw b particle radius am (corrected for polydispersity, obeying the relation Mw=(4/r/3) p am3), c structure density p 1( ) - NaPSS/PDADMAC, X=0.3, 2(0) - NaPSS/PDADMAC, X=0.6, 3(B) - DADMAC-acrylamide copolymer (47 mol% DADMAC)/NaPMA X=0.6, 4(V) - DHP2 (block copolymer of poly(2-acry-lamido-2-methyl-1-propanesulfonic acid) and poly(ethylene glycol), PEG block length 10 kda)/PDADMAC, X=0.6,1-4 addition of NaCl, 5(A) - DADMAC-acrylamide copolymer (47 mol% DADMAC)/Na-PMA, X=0.6, addition of CaCl2...

Besides the above-mentioned approaches varying the parameters governing the initiator decomposition, it is worth mentioning an interesting biphasic study based on the difference of solubility of monomers and the use an original amphiphilic bifunctional initiator, the palmitoyl (3-carboxy propionyl) sebacoyl diperoxide 3 [24], In such conditions, block copolymers of water soluble (acrylamide) and oil soluble (butylmethacrylate) monomers can be obtained by interfacial radical copolymerization as follows ... 

Block copolymers with hydroxyl segments were prepared by various ways An example utilizes the copper-catalyzed sequential copolymerizations of nBA and 2-[(trimethylsilyl)oxy]ethyl acrylate by the macroinitiator method into B-31 to B-33. The copolymers were then hydrolyzed into amphiphilic forms by deprotection of the silyl groups.313 A direct chain-extension reaction of polystyrene and PMMA with HEMA also afforded similar block copolymers with hydroxyl segments (B-34 and B-35).241-243 In block polymer B-36, a hydroxy-functionalized acrylamide provides a hydrophilic segment.117 Block copolymers of styrene and p-acetoxystyrene (B-37 to B-39), prepared by iron... 

Carboxyl groups may be introduced into block copolymers via direct polymerizations of free-acid monomers or protection—deprotection procedures. Block copolymers of styrene and nitrophenyl methacrylate (B-40) are used for the latter method, where the activated ester pendant is effectively converted into methacrylic acid or acrylamide under mild conditions.166 A homogeneous aqueous system with copper catalysts gives block copolymers with benzoate groups (B-41) via sequential block copolymerization of the two water-soluble monomers.247... 

Anionic polymerization of lactams offers the best approach to the preparation of polyamide containing block copolymers. Styrene-nylon 6 block copolymers were prepared by adding e-caprolactam to polystyrene macroanions terminated with bisphenol A bis(chlorofor-mate)(31). Yamashita prepared ABA block copolymers of styrene-a-pyrrolidone and styrene- -caprolactam by sequential addition to styrene macroanions( ). Similarly Stehlik and Sebenda prepared N-acrylamide containing block copolymers(33). Block copolymers of isoprene-pivalolactam have also been reported( . In these cases the lactam was added to "living" polyisoprene anions. 

Hydrophobically associating acrylamide based polymers were explored as a means of alleviating the salt sensitivity observed in the block systems. A micellar polymerization technique was developed to enable preparation of random copolymers of acrylamide and N-n-alkylacrylamide. When these copolymers were dissolved in an aqueous solvent, the hydrophobic groups associated to minimize their exposure to water. The hydrophobic associations provided an additional dimension to polymer molecular weight and chain expansion by ionic groups for the control of aqueous fluid rheology. 

Topp, M.D.C., Dijkstra, P.J., Talsma, H. and Feijen, J. (1997) Thermosensitive miceUe-forming block copolymers of poly(ethylene glycol) and poly(N-isopropyl acrylamide). Macromolecules, 30, 8518-8520. 

Neradovic, D., Soga, O., Van Nostrum, C.R and Hennink, W.E. (2004) The effect of the processing and formulation parameters on the size of nanoparticles based on block copolymers of PEG and poly(N-isopropyl acrylamide) with and without hydrolytically sensitive groups. Biomaterials, 25,2409-2418. 

Hales, M., Barner-Kowollik, C., Davis, T. R, Stenzel, M. H. (2004). SheU-cross-hnked vesicles synthesized from block copolymers of poly(D,L-lactide) and poly(A-isopropyl acrylamide) as thermoresponsive nanocontainers. Langmuir, 20, 10809-10817. 

Masci and co-workers [9] characterised block copolymers of N-isopropyl acrylamide with dimethyl acrylamide or 3-sulfopropyl methacrylate by HPLC, gel permeation chromatography (GPC) and MALDI-ToF-MS. Data are provided on the reaction conditions, kinetic data, M and polydispersities for the polymers and copolymers. 

MAIs may also be formed free radically when all azo sites are identical and have, therefore, the same reactivity. In this case the reaction with monomer A will be interrupted prior to the complete decomposition of all azo groups. So, Dicke and Heitz [49] partially decomposed poly(azoester)s in the presence of acrylamide. The reaction time was adjusted to a 37% decomposition of the azo groups. Surface active MAIs (M, > 10 ) consisting of hydrophobic poly(azoester) and hydrophilic poly(acrylamide) blocks were obtained (see Scheme 22) These were used for emulsion polymerization of vinyl acetate—in the polymerization they act simultaneously as emulsifiers (surface activity) and initiators (azo groups). Thus, a ternary block copolymer was synthesized fairly elegantly. 

Generation of radicals by redox reactions has also been applied for synthesizing block copolymers. As was mentioned in Section II. D. (see Scheme 23), Ce(IV) is able to form radical sites in hydroxyl-terminated compounds. Thus, Erim et al. [116] produced a hydroxyl-terminated poly(acrylamid) by thermal polymerization using 4,4-azobis(4-cyano pentanol). The polymer formed was in a second step treated with ceric (IV) ammonium nitrate, hence generating oxygen centered radicals capable of starting a second free radical polymeriza-... 

NR, styrene-butadiene mbber (SBR), polybutadiene rubber, nitrile mbber, acrylic copolymer, ethylene-vinyl acetate (EVA) copolymer, and A-B-A type block copolymer with conjugated dienes have been used to prepare pressure-sensitive adhesives by EB radiation [116-126]. It is not necessary to heat up the sample to join the elastomeric joints. This has only been possible due to cross-linking procedure by EB irradiation [127]. Polyfunctional acrylates, tackifier resin, and other additives have also been used to improve adhesive properties. Sasaki et al. [128] have studied the EB radiation-curable pressure-sensitive adhesives from dimer acid-based polyester urethane diacrylate with various methacrylate monomers. Acrylamide has been polymerized in the intercalation space of montmorillonite using an EB. The polymerization condition has been studied using a statistical method. The product shows a good water adsorption and retention capacity [129]. 

Monofunctional and difunctional xanthates, shown in Scheme 30, were employed as chain transfer agents in the synthesis of block and triblock copolymers of acrylic acid, AA and acrylamide, AAm PAA-fr-PAAm, PAAm-fr-PAA-fo-PAAm and P(AA-sfaf-AAm)-fr-PAAm [81]. The polymerizations were conducted in aqueous solutions at 70 °C with 4,4 -azobis(4-cyanopentanoic acid) as the initiator. The yields were almost quantitative,... 

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