Novel temperature‐responsive water‐soluble copolymers based on 2‐hydroxyethylacrylate and vinyl butyl ether and their interactions with poly(carboxylic acids)

Novel water‐soluble amphiphilic copolymers have been synthesized by free radical copolymerization of 2‐hydroxyethylacrylate with vinyl butyl ether. In water these copolymers exhibit lower critical solution temperature, which depends on the content of hydrophobic vinyl butyl ether units. The interaction between these copolymers and poly(acrylic acid) or poly(methacrylic acid) in aqueous solutions results in formation of interpolymer complexes stabilized by hydrogen bonds and hydrophobic interactions. An increase in hydrophobicity of the copolymers leads to the enhancement of their complex formation ability with respect to poly(acrylic acid) and poly(methacrylic acid). Poly(methacrylic acid) forms stronger complexes with the copolymers when compared with poly(acrylic acid). The complexes exhibit dual sensitivity to pH‐ and temperature and this property may be easily adjusted regulating the strength of interaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 195–204, 2006     

Molecular structure and dynamics of poly(methacrylic acid) and poly(acrylic acid) complexes with dodecyl-substituted poly(ethylene glycol)

The molecular dynamics and the structure of molecular complexes formed by micelles of dodecyl-substituted poly(ethylene glycol) with poly(methacrylic acid) and poly(acrylic acid) in aqueous solutions were studied by viscosimetry, pH measurement, and electron spin resonance spin-probe techniques. At low surfactant concentrations, the conformation of the complex is a compact globule. The local mobility of surfactant molecules in such a complex is much slower than that in the free micelle. At high surfactant concentration, the nonionic micelles and polyacids form hydrophilic associates. The associates have the conformation of extended coils. In an associate, a major part of the micellar poly(ethylene glycol) groups is free. The local mobility of the micellar phase depends on the number of micelles involved in an associate. The mobility of surfactant molecules is slower in the complexes of poly(methacrylic acid) than in the complexes of poly(acrylic acid).     

Effect of external factors on the swelling of hydrogels based on poly(ethylene glycol) maleate with some vinyl monomers

Effect of the pH of the medium, temperature, and nature of solvents and inorganic salt on the behavior of hydrogels based on copolymers of poly(ethylene glycol) maleate with acrylic and methacrylic acids and acrylamide was studied. It was shown experimentally that the susceptibility of the hydrogels to changes in the factors mentioned above, depending on the nature of a comonomer.     

Complexation of poly(acrylic acid)s with uranyl ion

The complexation of uranyl ion (UO₂²⁺) in aqueous solution with polymers containing carboxylic acid groups was studied potentiometrically. Overall formation constants of the uranyl complexes with poly(methacrylic acid) and crosslinked poly(acrylic acid) were much larger than those with the corresponding low molecular carboxylic acids. Decrease in the viscosity of the polymer solution on adding uranyl ion indicated that poly(acrylic acid) forms intra-polymer chelates with uranyl ion. The crosslinked poly(acrylic acid) adsorbed uranyl ions at higher efficiency than transition metal ions.     

Polysalt complexes of poly(vinylbenzo-18-crown-6) and of poly(crown acrylate)s with polyanions

Macrocyclic polyether or crown ether ester derivatives of acrylic and methacrylic acid were synthesized and polymerized. The cation binding properties of the polymers determined by extraction of picrate salts were similar to those obtained for poly(crown ether)s derived from styrene. In the presence of a crown-complexable cation both polymers form insoluble polysalt complexes with sodium carboxymethylcellulose, potassium poly(styrene sulfonate), and potassium polyacrylate. The extent of precipitation depends on the type and concentration of cation as well as on the ratio polyanion to poly(crown ether). The precipitate appears to have an equal number of positive and negative charges. An insoluble hydrogen-bonded complex is formed in the absence of salt when poly(vinylbenzo-18-crown-6) and poly(acrylic acid) are mixed in 0.01M HCl. Organic solutes bound to the poly(crown ether)s, which occur in an aqueous mixture of poly(vinylbenzo-18-crown-6) and picrate anions, are precipitated with the poly(crown ether) when the polysalt complex is formed.     

Equilibrium study of polymer–polymer complexation of poly(methacrylic acid) and poly(acrylic acid) with complementary polymers through cooperative hydrogen bonding

The degree of linkage, θ, defined as the ratio of the binding groups to the total of potentially interacting groups and the stability constant K of the polymer–polymer complexes in the systems poly(methacrylic acid)–poly(ethylene glycol), poly(acrylic acid)–poly(ethylene glycol), and poly-(methacrylic acid)–poly(vinyl pyrrolidone) in aqueous and aqueous alcohol media were determined as a function of temperature by potentiometric titration. It was found that θ and K are strongly dependent on chain length, temperature, and medium and that hydrophobic interaction is a significant factor in the stabilization of the complexes. The enthalpy and entropy changes and the cooperativeness parameter of the systems were calculated. A mechanism for the complexation in terms of cooperative interaction was proposed.     

Hydrogels of copolymers of β-vinyloxyethylamide of acrylic acid with unsaturated carboxylic acids

The effect of external factors on the behavior of hydrogels based on copolymers of β-vinyloxyethylamide of acrylic acid with acrylic and methacrylic acids was studied. The response of hydrogels to changes in the pH of medium, the concentration of low-molecular-mass salts, and solvent quality was experimentally shown.     

Deuterium substitution and fluorescence studies on polymer hydrogels and complexes

Deuterium isotope effects on swelling kinetics and volume phase transition in typical polymer hydrogels (poly(N-isopropylacrylamide) and polyacrylamide gels) are discussed. Deuterium substitutions affect on the swelling kinetics and volume phase transition of the polymer hydrogels. The slower swelling kinetics of hydrogels in D₂O than in H₂O arises mainly from the high viscosity of the medium. The deuterium isotope effect on the swelling-shrinking curve of hydrogels would come from the different polymer-solvent interaction. The microenvironments of hydrogels studied by solvatochromic fluorescence probe are compared with the bulk state. The zipper-type hydrogen-bonding inter-polymer complexes (poly(acrylic acid)-polyacrylamide and poly(acrylic acid)-poly(N-acryloylglycineamide)) are also investigated and show the huge isotope effect on the phase separation temperature.     

Radiation synthesis of hydrogels based on copolymers of vinyl ethers of monoethanolamine and ethyleneglycol and their interaction with poly(acrylic acid)

Novel hydrogels of cationic nature were synthesized by gamma-radiation copolymerization of vinyl ethers of monoethanolamine and ethyleneglycol in the presence of cross-linking agent. The effect of absorbed dose on the gel fraction and equilibrium swelling degree of hydrogels in water is shown. It was demonstrated that the hydrogels are able to bind poly(acrylic acid) to form polyelectrolyte complexes with swelling properties typical for polyampholytes.     

Mutual enhancement of the complexing properties of components in tertiary systems containing copper nanoparticles, poly(acrylic acid), and poly(ethylene glycol)

It is shown that nonstoichiometric interpolymer complexes composed of high-molecular-mass poly( acrylic acid) and PEG of various molecular masses are more efficient stabilizers of copper sols than each component of the complex taken separately. This conclusion is based on comparison of dimensions of copper nanoparticles in sols formed via reduction of copper(II) ions in solutions of poly (acrylic acid), PEG, and their blends and on the enhanced stability of sols protected by the interpolymer complex against aggregation and oxidation of metal particles. Much shorter PEG chains than those necessary for formation of corresponding interpolymer complexes in the absence of nanoparticles can be involved in formation of tertiary complexes including copper nanoparticles, poly(acrylic acid), and PEG. On the basis of the experimental data, it is inferred that the mutual enhancement of the complexing behavior of components occurs in tertiary complexes containing copper nanoparticles and both polymers.     

Actuator based on MWNT/PVA hydrogels

The first actuator based on multiwalled carbon nanotube (MWNT) hydrogels was developed through simple hydrogelation with poly(vinyl alcohol) (PVA). This actuator exhibited excellent actuating properties compared with the corresponding actuator based on poly(acrylic acid)/PVA hydrogels.     

Polyelectrolyte complexes of soluble poly-2-[(methacryloyloxy)ethyl]trimethylammonium chloride and its hydrogels with poly(acrylic acid)

The complex formation of poly-2-[(methacryloyloxy)-ethyl]trimethylammonium chloride (PMADQUAT) with poly(acrylic acid) (PAA) of different molecular weights has been studied in aqueous solutions by potentiometric, viscometric, turbidimetric and FTIR spectroscopic methods. The formation of insoluble non-stoichiometric polyelectrolyte complexes has been shown. The stability of polyelectrolyte complexes in solutions of different pH and ionic strength has been evaluated. The formation of polyelectrolyte complexes between hydrogels of PMADQUAT and linear PAA of different molecular weights has been studied. It was shown that the molecular weight of PAA considerably affects the kinetics of interaction as well as the final state of gel-polymer complex.     

Characteristics of proflavine solubilized in complexes of anionic polymers with a cationic surfactant

Absorption and emission spectra of 3,6-diaminoacridine (proflavine) are reported in mixed solutions of dodecyltrimethylammonium bromide (DTAB) with various polyelectrolytes including the sodium salts of poly(acrylic acid) (PAA). poly(methacrylic acid) (PMA), poly(styrenesulfonic acid) (PSS), poly(garacturonic acid) (pectate), and the alternating copolymers of maleic acid with ethylene (PMA-E) and styrene (PMA-S). The spectral change indicates the association of the dye (blue-shift) on these polyions except on PSS, the easy dissociation of the aggregated form into the monomeric form and the solubilization into the hydrophobic PMA-S/DTAB complex (red-shift), the little dissociation in the PAA/DTAB, PMA/DTAB and PMA-E/DTAB complexes, and the liberation of the bound dye in the case of pectate/DTAB complexes. In the PSS system, the strong interaction of the dye with the styrene groups induces the completely different spectral behavior. These results are discussed with the cooperative binding of the dye and the surfactant ion.     

Complexation Constants of Lanthanide Ions with Poly(Methacrylic Acid) and its Copolymers

Complexation of some lanthanide ions with poly(methacrylic acid) and its copolymers was studied by potentiometric titration. Poly [methacrylic acid-co-oligo(ethylene oxide)methacrylate] and poly(methacrylic acid-co-acrylamide) formed tris-carboxylate coordinate lanthanide complexes with large overall complexation constants, while poly-(methacrylic acid)s and copolymer with higher content of the methacrylic acid residue formed bis-coordinate ones. It was concluded that the comonomer residues in the copolymer chains decreased the steric hindrance for the complexation and/or acted as co-coordinating groups of the carboxylic group to lanthanide ions. Very large positive and favorable entropy changes were observed for the complexation with poly(methacrylic acid) and its copolymers. This contribution of thermodynamic parameters to the complexation was contrary to that for the analogous monomeric methacrylic acid complex and is assumed to be induced by dehydration of the polymers through the lanthanide ion complexation.     

Green pH- and magnetic-responsive hybrid hydrogels based on poly(methacrylic acid) and Eucalyptus wood nanocellulose for controlled release of ibuprofen

Cellulose - pH- and magnetic-sensitive hybrid hydrogels based on poly(methacrylic acid) (PMAA), nanocellulose (NC), carboxymethyl cellulose (CMC) and magnetite particles (MN) were prepared as...     

Polymerisation radiochimique de l''acide methacrylique en solution

The polymerization of methacrylic acid was investigated in various solvents under the action of gamma-rays. It was found that, as in the case of acrylic acid, solvents could be divided into groups according to the observed effects. The addition of methanol or dioxane up to 50 per cent does not significantly alter the polymerization rate. These two solvents do not dissociate the plurimolecular aggregates of methacrylic acid, the presence of which is demonstrated by the high viscosity of the medium. In the presence of either toluene or n-hexane, the rate gradually decreases and the aggregates are dissociated. Chloroform and CCl₄ also dissociate the aggregates but lead to acceleration of the reaction. This effect which was not observed with acrylic acid presumably results from an energy transfer process. The polymerization of methacrylic acid in bulk and in solution has a very small overall activation energy, 1·0–1·5 kcal/mole between 16 and 60°. All conversion curves are linear in contrast to the case of acrylic acid where auto-accelerated conversion curves were observed in most mixtures. A comparison of these results shows that the initial rates of polymerization of acrylic acid follow relationships similar to those observed for methacrylic acid except for the chlorinated solvents. It is concluded that the molecular aggregates produce the same influence on the polymerization of methacrylic acid as on the initial stages of the reaction for acrylic acid, but the “matrix effect” of poly(acrylic acid) does not appear in the case of poly(methacrylic acid).     

Synthesis and Properties of IPN Hydrogels Based on Konjac Glucomannan and Poly（acrylic acid）

As a random copolymer of β-(1,4) linked D-mannose and D-glucose, konjac gluco- mannan (KGM) is a naturally occurring water-soluble polysaccharide, and has been paid attention in the field of drug controlled release carriers potentially used in colon1,2. …     

Cope elimination and complexation of poly(dimethylaminoethyl methacrylate N-oxide)

Poly(dimethylaminoethyl methacrylate N-oxide) (poly(DMAEMNO)) was prepared by oxidation of poly(dimethylaminoethyl methacrylate) with hydrogen peroxide in methanol. From thermogravimetric and IR spectroscopic investigations Cope elimination of amine oxide group in poly(DMAENO) was found to occur at 120–150°C. The postpolymerization of partially pyrolyzed polymer carrying vinyl ester group as pendant was performed with azobisisobutyronitrile at 60°C in methanol to give cross-linked polymer that was found to form hydrogel. Poly(DMAEMNO) gave metal–polymer complexes with CuCl₂, ZnCl₂, and CoCl₂. Cobalt–polymer complex had a constitution of 1:2 of metal ion to amine oxide group, while copper– and zinc–polymer complexes seemed to have structures of 1:1 and 1:2 of metal ion to amine oxide group. Furthermore, polymer complexes of poly(DMAEMNO) with poly(methacrylic acid) and poly(acrylic acid) were found to be formed by mixing aqueous solutions of both polymers and also by radical polymerization of the acid monomers in the presence of poly(DMAEMNO). From elemental analysis, thermogravimetric investigation, and measurement of turbidity it was concluded that the resulting polymer–polymer complexes contained more than one acid monomer unit per one N-oxide unit.     

Sucrose diacrylate: A unique chemically and biologically degradable crosslinker for polymeric hydrogels

A series of degradable hydrogels based on different vinyl monomers such as acrylamide, sucrose-1′-acrylate, and acrylic acid were synthesized using sucrose-6,1′-diacrylate (SDA) as a crosslinking agent. SDA was prepared by enzymatic transesterification of vinyl acrylate with sucrose in pyridine. Base catalyzed hydrolysis of SDA in aqueous solution was studied as a function of pH. As expected, hydrolysis of SDA was faster at higher pHs such that poly(acrylamide), poly(sucrose 1′-acrylate), and poly(acrylic acid) hydrogels underwent substantial degradation at and above pH 7, 9, and 13, respectively. The degradation was characterized by changes in the swelling ratios of the hydrogels indicating breakage of the crosslinking agent. Degradation of the hydrogels at their chemically stable pHs was studied in presence of enzymes. Enzymes, including pepsin and a fungal Lipase, were able to degrade the poly(acrylamide) hydrogel at pH 4 and 5, respectively. Poly(acrylic acid) hydrogel was degraded in presence of a fungal protease at pH 7.8. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2221–2229, 1997