Spontaneous change in thermosensitive properties of aqueous solutions of poly(<Emphasis Type="Italic">N,N</Emphasis>-dimethylaminoethyl methacrylate) and its mixtures with sodium dodecyl sulfate

It is shown that the properties of aqueous solutions of poly(N,N-dimethylaminoethyl methacrylate) are unstable over time: the pH value spontaneously decreases, the phase separation temperature grows, and the light scattering ability of dispersions arising above the said temperature weakens. These effects are enhanced after dilution of solutions, become less pronounced with an increase in pH, and disappear when the solutions are isolated from atmosphere (under argon). It is inferred that the lability of the indicated properties is associated with acidification of polymer solutions due to their interaction with air carbon dioxide and the enhancement of protonation of macromolecules. Potentiometric and tensiometric measurements have demonstrated that upon introduction of sodium dodecyl sulfate into solutions of poly(N,N-dimethylaminoethyl methacrylate), the surfactant-polymer interaction slows down owing to a spontaneous increase in the charging of macromolecules in the course of time.     

Synthesis of N,N-dimethylaminoethyl methacrylate copolymers with N-vinyl caprolactam and their complexing and flocculating behavior

Thermosensitive copolymers of N-vinyl carprolactam with N,N-dimethylaminoethyl methacrylate have been synthesized via free-radical polymerization, and reactivity ratios in dioxane have been estimated as 2.44 and 0.07, respectively. It has been shown that temperatures of phase separation for 1% aqueous solutions of homopolymers are close and remain virtually unchanged with the copolymer composition. The efficiency of flocculating behavior of copolymers with respect to a polystyrene latex has been estimated from the initial rate of flocculation as a function of the polyelectrolyte concentration in an acidic medium.     

Heterocoagulation of anionic and cationic latexes with particles bearing intrinsic charge

Kinetics of coagulation of dilute latexes of styrene copolymers with methacrylic acid and N-dimethylaminoethyl methacrylate is studied turbidimetrically. The pH dependence of the limiting turbidity of the coagulating dispersion, characterizing the heterocoagulation efficiency, is examined.     

Conformational and dynamic characteristics of copolymers of N,N-dimethylaminoethyl methacrylate and 2-deoxy-2-methacrylamido-D-glucose

The conformational and relaxation properties of N,N-dimethylaminoethyl methacrylate and 2-deoxy-2-methacrylamido-D-glucose copolymers in solutions are studied by the methods of molecular hydrodynamics (sedimentation, diffusion, viscometry), polarized luminescence, and flow birefringence. Kuhn-Mark-Houwink equations are obtained, and Kuhn statistical segment lengths at various degrees of protonation of amino groups are estimated. It is found that there is a correlation between the Kuhn statistical segment length and the intramolecular mobility of the copolymers.     

Effect of reactant association on addition of tertiary amines to acrylic acid in aqueous solutions

The formation of betaines by the reaction of tertairy amines (N,N-dimethyl-N-2-hydroxyethylamine, N,N-dimethylaminoethyl methacrylate, N-methylmorpholine, N,N-dimethylaminopropionitrile, 1,4-diazabicyclo[2.2.2]octane) with acrylic acid in aqueous solutions in a wide concentration range was studied. The concentration effects observed were interpreted taking into account the association of the starting reagents.     

Grafting copolymerization of vinyl monomers on polyimide macroinitiators by the method of atom transfer radical polymerization

Graft copolymers with the main polyimide chain and side chains of poly(n-butyl acrylate), poly(tert-butyl acrylate), poly(methyl methacrylate), poly(tert-butyl methacrylate), polystyrene, and polystyrene-block-poly(methyl methacrylate) were synthesized by atom transfer radical polymerization on the multicenter polyimide macroinitiators in the presence of the halide complexes of univalent copper with nitrogen-containing ligands. Polymerization of metha-crylates is most efficiently developed on the polyimide macroinitiators. The obtained graft copolymers initiate the secondary polymerization (“post-polymerization”) of methyl methacrylate. The conditions of detachment of side chains of graft polymethacrylates that do not involve the ester groups of their monomeric units were found. The molecular mass characteristics of the graft copolymers and isolated polymers, being the detached side chains of the copolymers, were determined. The detached side chains of different chemical structures have low values of the polydispersity index. The procedure developed was used for the preparation of new graft polyimides with side chains of poly-4-nitro-4′-[N-methylacryloyloxyethyl-N′-ethyl]amino-azobenzene that cause the nonlinear optical properties and with the side chains of poly(N,N-dimethylaminoethyl methacrylate) that cause the thermosensitive properties of the copolymers.     

NMR study of phase separation in D2O/ethanol solutions of poly(N-isopropylmethacrylamide) induced by solvent composition and temperature

¹H and ¹³C NMR spectroscopies were applied to investigate phase separation in solutions of poly(N-isopropylmethacrylamide) (PIPMAm) in D₂O/ethanol (EtOH) mixtures induced by solvent composition (cononsolvency) and temperature. Effects of EtOH content in D₂O/EtOH mixtures and temperature on the appearance and extent of the phase separation were characterized. Differences in mesoglobules formed during the phase separation induced by cononsolvency and temperature were found. For temperature-induced phase separation, ¹³C spin-spin relaxation times showed that besides the free EtOH expelled from the PIPMAm mesoglobules, there are also EtOH molecules bound in these mesoglobules. On the other hand, virtually no bound EtOH molecules were detected for mesoglobules formed as a consequence of the cononsolvency. For PIPMAm random copolymers containing negatively charged methacrylate units the phase separation induced by solvent composition was not observed.     

Effect of molecular weight of poly-<Emphasis Type="Italic">N</Emphasis>-benzyl-<Emphasis Type="Italic">N,N</Emphasis>-dimethyl-<Emphasis Type="Italic">N</Emphasis>-methacryloyloxyethylammonium chloride on its complexation with sodium dodecyl sulfate

Complexation of a cationic polyelectrolyte, poly-N-benzyl-N,N-dimethyl-N-methacryloyloxyethylammonium chloride, with an ananionic surfactant, sodium dodecyl sulfate, in aqueous solutions is studied. The effect of the molecular weight of the polymer on phase separation in the system and on the stability, conformation, and surface activity of the polyelectrolyte-surfactant complexes is examined.     

Copolymers of 2-deoxy-2-methylacrylamido-<Emphasis Type="Italic">D</Emphasis>-glucose with tertiary and quaternary amino groups

Method for synthesis of graft-copolymers of a vinyl saccharide, 2-deoxy-2-methylacrylamido-D-glucose, and N,N-dimethylaminoethyl methacrylate was developed. Statistical copolymers with a controllable hydrophobic-hydrophilic balance were synthesized by alkylation of a statistical copolymer with various alkyl iodides.     

Copolymerization in N-vinylcaprolactam-N-vinylpyrrolidone and N,N-diethylacrylamide-N,N-dimethylacrylamide systems: The effect of composition and spatial structure of copolymers on their thermal sensitivity

Factors that affect the temperature-responsive properties of water-soluble polymers were revealed by studying the copolymerization of two pairs of monomers: N-vinylcaprolactam-N-vinylpyrrolidone and N,N-diethylacrylamide-N,N-dimethylacrylamide. In each pair, the first monomer forms a temperature-responsive polymer and the second gives a polymer soluble in water up to the boiling point. It was found that in all cases, the addition of the second (more hydrophilic) monomer resulted in a monotonous increase in the phase separation temperature in an aqueous copolymer solution, with the temperature rise being comparatively slow in the initial stage and sharply accelerating after the addition of more than 40–50 mol % second monomer. The phase-separation temperature versus copolymer composition curves for N,N-diethylacrylamide-N,N-dimethylacrylamide copolymers of iso-and heterotactic structure synthesized via anionic polymerization are rather similar. At the same time, the copolymers of both types prepared via radical polymerization are characterized by steeper curves, a pattern that may be due to a high content of the syndiotactic structure, however, changes in the copolymer spatial structure have a lesser effect on the phase separation temperature than the presence of units of a more hydrophilic monomer. The addition of a relatively low amount (20–25 mol %) of a less hydrophilic monomer imparts temperature sensitivity to polymers, such as polyvinylpyrrolidone or polydimethylacrylamide, which do not possess this property in the pure form.     

Temperature-induced phase transition of poly(N,N-dimethylaminoethyl methacrylate-co-acrylamide)

Copolymers of N,N-dimethylaminoethyl methacrylate (DMAEMA) and acrylamide (AAm) were prepared to demonstrate a temperature-induced phase transition. Poly DMAEMA has a lower critical solution temperature (LCST) around 50°C in water. With copolymerization of DMAEMA with AAm, the LCST shifts to the lower temperature was observed, probably due to the formation of hydrogen bonds between amide and N,N-dimethylamino groups. FT-IR studies clearly show the formation of hydrogen bonds which protect N,N-dimethylamino groups from exposure to water and result in a hydrophobic contribution to the LCST. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 595–598, 1997     

Concentration effects in copolymerization of sulfuric acid salt of <Emphasis Type="Italic">N,N</Emphasis>-dimethylaminoethyl methacrylate with acrylonitrile and acrylamide in aqueous solutions

Copolymerization of sulfuric acid salt of N,N-dimethylaminoethyl methacrylate with acrylonitrile and acrylamide in aqueous solution was studied.     

Flocculation of Butadiene-Styrene Latex with Polymeric Ammonium Salts of N,N-Dimethylaminoethyl Methacrylate and Mineral Acids

The flocculation performance of cationic polyelectrolytes (polymeric ammonium salts of N,N-dimethylaminoethyl methacrylate) and mineral acids (HCl, HNO₃, H₂SO₄, H₃PO₄) in recovery of rubber from SKS-30 ARK butadiene-styrene latex was studied.     

ABA-type amphiphilic triblock copolymers containing p-ethoxy azobenzene via atom transfer radical polymerization: Synthesis,characterization, and properties

ABA-type amphiphilic triblock copolymers composed of poly(ethylene glycol)s (PEGs) with different number-average molecular weights as the hydrophilic blocks (B) and poly{6-[4-(4-ethoxyphenylazo)phenoxy]hexyl methacrylate} (PA6C) as the hydrophobic blocks (A) were prepared via atom transfer radical polymerization. These copolymers were prepared from bromo-terminated macroinitiators based on PEG6000, PEG2000, and PEG600, with CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine as the catalytic system, at 85 °C in anisole. The block copolymers were characterized with ¹H NMR spectroscopy and gel permeation chromatography. Differential scanning calorimetry measurements were performed to reveal the phase segregation. In contrast to those polymers with similar compositions and structures in previous reports, these amphiphilic copolymers exhibited unusual liquid-crystalline properties over a wide temperature range, being stable even at room temperature. These copolymers showed photoresponsive isomerization under the irradiation of UV–vis light both in THF solutions and in solid films. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2225–2234, 2007     

Binding of methyl orange and the hydrophobic fluorescent probe, 2-p-toluidinylnaphthalene-6-sulfonate,by 2-dialkylaminoethyl methacrylate-N-vinyl-2-pyrrolidone and related copolymers

The copolymers of N-vinyl-2-pyrrolidone and 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, 2-dimethylaminoethyl acrylate, or 2-dimethylaminopropyl acrylamide have been prepared. Studies were made of the binding of a “binding probe,” methyl orange, by the copolymers in aqueous solution. The first binding constants accompanying the binding were evaluated. Furthermore, the intensity of fluorescence of a hydrophobic fluorescent probe, 2-p-toluidinylnaphthalene-6-sulfonate, in the presence of these polymers was investigated. The nature and phenomena of dye binding and hydrophobic fluorescent probe binding with the polymers are discussed.     

Temperature-induced chiral nematic phase changes of suspensions of poly(N,N-dimethylaminoethyl methacrylate)-grafted cellulose nanocrystals

Temperature-induced copolymers of poly(N,N-dimethylaminoethyl methacrylate)-grafted cellulose nanocrystals (PDMAEMA-grafted CNC) were synthesized by surface-initiated atom transfer radical polymerization (ATRP). The graft copolymers were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC). The size of the original CNC was 10–40 nm in width and 100–400 nm in length, as characterized by atomic force microscopy (AFM). The liquid-crystalline properties of the graft copolymers were investigated by using polarizing optical microscopy (POM). The graft copolymers exhibited fingerprint texture in lyotropic state. The temperature-induced fingerprint texture changes of PDMAEMA-grafted CNC aqueous suspensions were investigated at various temperatures. With increasing temperature, the spacing of the fingerprint lines decreases. Temperature-induced changes of PDMAEMA polymer chains result in changes of fingerprint texture.     

Copolymerization of N-vinylcaprolactam with N-vinyl(benz)imidazoles and the properties of aqueous solutions of the copolymers

The free-radical solution copolymerization of N-vinylcaprolactam with 1-vinylimidazole, 1-vinyl-2-methylimidazole, 1-vinyl-2-methyl-3-propylimidazolium iodide, or 1-vinyl-2-methylbenzimidazole was investigated and the monomer reactivity ratios in the copolymerization were calculated. It was shown that 1-vinylimidazole exhibits a relatively higher activity in the copolymerization as compared to the monomers that bear substituents on the ring. It was established that, except for the copolymers of 1-vinyl-2-methylbenzimidazole, water-soluble products could be obtained. Aqueous solutions of N-vinylcaprolactam copolymers with N-vinyl(methyl)imidazoles were found to have a higher phase separation temperature relative to poly(N-vinylcaprolactam) solutions. The thermal stability of the aqueous solutions increases with a rise in the amount of hydrophilic 1-vinyl-and 1-vinyl-2-methylimidazole units in macromolecular chains and in the presence of NaCNS or KBr. The effect of salts on the thermal stability of aqueous copolymer solutions has the same character as in the case of the N-vinylcaprolactam homopolymer.     

Kinetics of synthesis of monomeric betaines in aqueous solutions

In the nucleophilic addition of N-(3-dimethylaminopropyl)methacrylamide to acrylic acid (1 : 1) in aqueous solutions, forming monomeric β-propiobetaine, the dependence of the initial rate on the starting reagent concentration was found to have a pronounced maximum (whose position does not depend on the temperature at 30–70°С). In the case of the addition of N,N-dimethylaminoethyl methacrylate, the dependence was exponential. The dependences of equilibrium conversions on the starting reagent concentrations were of the same type and had a maximum for both systems. The detected concentration effects are related to the peculiarities of the pre-reaction association of the reagents.     

Influence of the lyophilizing power of the polymer chain on the relationships in formation of polyelectrolyte-surfactant complexes

Viscometry and turbidimetry were applied to examine the relationships in formation of complexes by poly-1,2-dimethyl-5-vinylpyridinium methyl sulfate, poly-N,N,N,N-trimethyl(methacryloyloxyethyl)ammonium methyl sulfate, and poly[N-benzyl-N,N-dimethyl-N-(methacryloyloxyethyl)]ammonium chloride with sodium dodecyl sulfate.     

Thermosensitivity of poly(<Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone): Effect of transition-metal halides

The effect of the halides of a series of transition metals on the properties of aqueous solutions of poly(N-vinylpyrrolidone) is studied. It is shown that the introduction of ZnCl₂ into solutions of poly(N-vinylpyrrolidone) causes phase separation with an increase in temperature. In the presence of halides of other transition metals (CdCl₂, CuCl₂), this phenomenon is not observed. However, the addition of HCl and/or alkali-metal halides to these systems likewise gives rise to phase separation, and in the ZnCl₂-based systems, the cloud point of solution substantially decreases with the introduction of alkali-metal salts. The same situation is observed in the case of polyvinylcaprolactam. Thus, it is concluded that the observed phenomena are associated with the formation of MtCl₄²⁻ complex anions in solutions that promote the globulization of polymer chains with participation of water molecules surrounding polymer chains and cations of transition-metal salts bound to complexes with C=O groups of lactam rings of the polymers.