Acrylamide/DADMAC

Copolymers from the monomers AMPS, diallyldimethylammonium chloride (DADMAC), N-vinyl-N-methylacetamide (VIMA), acrylamides, and acrylates are particularly useful for fluid loss additives [824]. The molecular weights of the copolymers range from 200,000 to 1,000,000 Dalton. The copolymers are used in suspensions of solids in aqueous systems, including saline, as water binders. In these systems, the water release to a formation is substantially reduced by the addition of one or more of these copolymers. 

Polymers of N, N, N, A-diallyldimethylammonium chloride (DADMAC) (and its copolymers with acrylamide) are allyl resins in terms of the monomers used but are very different in properties since they are not crosslinked. Cyclopolymerization is the mode of reaction (Sec. 6-6b) and the polymers are water-soluble. Applications include potable and wastewater treatment (flocculation aid) and paper and textile industries (antistatic coating, reinforcement, color removal). 

C-NMR spectroscopy has also been used to investigate the composition of DADMAC copolymers [38, 45-47]. Copolymers with acrylamide (AAM) have been extensively studied. Based on the chemical shifts in the 13C-NMR spectra of the homopolymers of DADMAC [17-19] and AAM [48-50], the copolymer spectra can be analyzed. Specifically from two likely chad structures (m/r) in PAAM and six different diad structures (r/m, c/t) in PDADMAC, eight different diad structures can be expected for the copolymers. A detailed NMR analysis has therefore been carried out in order to determine the copolymer compositions. The reactivity ratios obtained were found to be in good agreement with the results from other methods, such as potentiometric titration or elementary analysis, provided that the DADMAC in the copolymer was below approximately 70% [38]. 

One objective of the copolymerization of DADMAC is to obtain higher polymer molar mass since the molar mass of the homopolymer is limited by a slow chain propagation (Table 4). Therefore, DADMAC has been copolymerized with various ionogenic and nonionic monomers of which acrylamide is the most common. A variation of the general properties such as water solubility or charge density also becomes possible by copolymerization. 

Fig. 12. Copolymerization DADMAC/acrylamide in aqueous solution. Influence of the initial monomer concentration on the copolymer composition (— data taken from [64] data taken from [65])...

Comparing the reactivity ratios of the DADMAC/AAM copolymerization with results of the copolymerization of other cationic monomers with AAM, significant differences can be identified. The differences between rx and r2 are much lower, and the cationic monomer even reacts preferentially during the copolymerization. As an example, for cationic methacrylic esters and methacrylamid derivatives, 1 nonideal copolymerization preferring the cationic component. For the cationic analogs of acrylic acid and acrylamide, 0.34azeotropic copolymerization, preferring the cationic monomer only at low content in the comonomer mixture. 

From these results, it can be concluded, that the structure of the growing chain end not only influences the addition of the cationic monomer but also the propagation step with acrylamide [38]. Figure 13 shows a comparison of the experimental results with the penultimate model and the best fit using the Keh-len/Tiidos equations [71]. A better agreement can be observed particularly in the range of higher DADMAC content. 

Homopolymers of DADMAC and copolymers of acrylamide and DADMAC are applied in the coagulation of fibers recycled from coated broke, a term used to describe a paper which cannot be sold for different reasons [ 176]. It is claimed that polymer solutions and water-in-oil emulsions containing DADMAC offer both superior performance and cost effectiveness compared to the traditional polymer additives used for this purpose [190,194]. 

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...

NaPMA, Mw = 114,000 g/mol). Polycations poly(diallyldimethylammo-nium chloride) (PDADMAC, Mw = 250,000 g/mol) and its copolymers (DADMAC-AA-xr, where xx corresponds to the mol% of DADMAC) with acrylamide of various compositions. Additionally, some findings will be given about PECs between ionically modified pol y(/V-is< >pr< tpylacrylamide) (PNIPAM). 

Materials. DADMAC, AMBTAC, and TAMAC monomers were produced internally by Calgon Corporation. The acrylamide monomer, received in bulk, was purchased from American Cyanamid. The MBA used was reaction grade from Aldrich Chemical. All monomers were used as received without further purification. 

DADMAC/Acrylamide Copolymer (75/25 Wt %)-Emulsion Polymerization. The following were added to the reaction vessel 64.4 parts benzene, 15 parts DADMAC, 5 parts acrylamide, 13.5 parts deionized H20, and 2 parts sodium octyl phenoxyethoxy-2-ethanol sulfate. The vessel was purged for 1 hr with N2 at 50° 1°C after which 5 ppm Fe+2 and 2 X 10"3 mol f-butylperoxypivalate/mol monomer were added. The temperature was held at 50° 1°C for 20 hr. The product, isolated via acetone precipitation, was found to be a DADMAC/acrylamide copolymer (60/40 wt %). 

DADMAC/Acrylamide Copolymer (75/25 Wt %)-Solution Polymerization. This product was synthesized in a manner similar to the solution homopolymerizations of DADMAC and AMBTAC. The product, isolated via acetone precipitation, was found to contain 60% DADMAC and 40% acrylamide. 

The effect of branching on the performance of 75% DADMAC/25% acrylamide copolymers in dewatering 100% waste-activated sludge was also investigated. A series of copolymers was prepared by an inverse emulsion method adding up to 0.5 mol % TAMAC (based on DADMAC... 

In the present work, the copolymerization of acrylamide (AAM) with three cationic comonomers DADMAC, dimethylaminoethyl methacrylate (DMAEM), and dimethylaminoethyl acrylate (DMAEA) (the latter two qua-temized with methyl chloride) was investigated. The reactivity ratios were determined by using continuous solution polymerization with the error-invariables method, a technique that provides estimates of the joint confidence... 

Some commercial low molecular weight polyacrylamides (LMPAM) are manufactured in solution and sold at 10-50% solids. For example, LMPAM containing DADMAC comonomer is made at 40% solids and can be reacted with glyoxal to produce a strengthening resin for paper. Furthermore, LMPAM hydrolyzed with sodium hydroxide to polyacrylate is manufactured at 30% solids and is used as an antisealant. High molecular weight poly(acrylamide) is also prepared in solution at 2-6 wt% solids and is often further modified using, for example, the Mannich reaction. 

DADMAC 13C, for example, can be readily polymerized imder these cyclopolymerization conditions to yield PolyDADMAC in which a structure composed of 5-membered A -heterocycles predominates. 13C will readily polymerize at 35°C employing ammonium persulfate as the initiator. 13C is readily copolymerized with other diallyl monomers, with acrylamide monomers such as 28C or diacetone acrylamide, or quaternized 1C. Extensive reviews of cyclopol5mieriza-tion and cyclocopolymerization can be found in Reference 188. Recent examples of cyclocopolymerization with sulfobetaine (14C) and carboxybetaine (15C) diallyl ammonium monomers are given in References (188-191). 

Most water and waste water treatment applications use polymers that are cationic in character that are predominantly prepared by copolymerisation of acrylamide with varying proportions of amino derivatives of acrylic acid or methacrylic acid esters. The most commonly used monomers in this class are dimethyl amino ethyl (meth) acrylate quater-nised with methyl chloride or other quaternising agents. Polymerisation is conducted under acidic conditions to prevent base catalysed hydrolysis of the ester linkage. Copolymers with allyl monomers, such as DADMAC are also manufactured however the molecular weight of these polymers is limited by the relative stability of the intermediate radical. 

FIGURE 12.6 Computed number-average sequence length of the dimethyl acrylamide (DMA) and diaUyldimethylammonium chloride (DADMAC) comonomers, and, for several copolymerization reactions with different initial compositions. From Li Z,... 

Polyacrylamides of high commercial interest are copolymers of acrylamide, 1, with sodium or ammonium salts of acrylic acid, 4, or 2-acrylamido tert-butylsulfonic acid (ATBS), 5, to produce anionic polymers or with aCTyloyloxyethyltri-methylammonium chloride (AETAC), 6 (Fig. 19.2), to produce cationic polymers. Although not produced in large volume, copolymers of acrylamide and DADMAC, 10, are used to produce cationic polymers for use in papermaking applications (Fig. 19.2). Polyacrylamides with a variety of charge densities... 

Subsequently, there have been many improvements to the dispersion polymerization process that have allowed for AM/ AETAC and AM/DADMAC cationic, AM/sodium aaylate anionic, acrylamide nonionic, and AM//V7V-dimethyl-/V-acryloyloxyethyl-/V-(3-sulfopropyl) ammonium betaine polymeric dispersions [16, 38-41]. These improvements, such as the development and utilization of new dispersants, the use of polymeric seeds to fecilitate precipitation, optimization of... 

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