IR and Raman Investigation of Some Poly(acrylic) Acid Gels in Aqueous and Neutralized State (original) (raw)
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Laser Raman spectroscopy of polyacrylamide
Journal of Polymer Science: Polymer Physics Edition, 1981
The Raman spectra of polyacrylamide and its covalently crosslinked gel (with N,N'-methylenebis-acrylamide as the crosslinking agent) in the region of 200-3600 cm-l are discussed. The vibrational band assignments for polyacrylamide are made on the basis of a comparison with the spectra of acrylamide, acrylic acid, polyacrylic acid, poly(viny1 alcohol), and other vinyl polymers. The Raman spectra of polyacrylamide in the solid phase and in aqueous solution have similar spectral features. The Raman spectra of gels with low crosslink content and of polyacrylamide in aqueous solution are comparable except that one new band, predominantly due to the residual monomer, appears in the gel phase. An analysis based on polarized Raman, infrared and NMR spectra, model building, and group theoretical calculations suggests a structure dominated by isotactic species.
Stimulus response of photopolymerized 1% and 0.5% N,N 0-methylene bisacrylamide (MBA) crosslinked 10% polyacrylamide (PAAm) hydrogels was studied in nitric acid. The hydrogels swelled exponentially to saturation in 13 h due to the osmotic pressure arising from diffusion of ions in to the gel. MBA (0.5%) gels swell more with larger time constant than 1% MBA gels due to lower bulk modulus. Diffusion coefficient of nitric acid in the hydrogel and polymer-solvent interaction parameter were estimated from the swelling behavior and discussed. At longer times, the hydrogels deswelled linearly in nitric acid due to molecular modification of amide group by acidic hydrolysis. Degree of swelling and deswelling increase with nitric acid concentration. Raman and FTIR investigations revealed the formation of carbox-ylic acid due to acidic hydrolysis. V
2006
ATR FTIR and Raman spectra of polymers containing amide groups in the main chain and in the side chain and of the amide low-molecularweight model compounds in water media were measured. The hydrophobic and hydrophilic interactions of the dissolved compounds with the neighboring water molecules are reflected in the wavenumbers of the CH 3 stretching and of the Amide I and II vibrations. The possibility of the existence of b-sheet-like structures in polypeptides surrounded by water molecules is also discussed.
Electrochimica Acta, 1995
electrolytes based on polymethymetacrylate (PMMA) have been obtained using propylene carbonate and ethylene carbonate as gelating agents. They have a good mechanical stability, solvent retention and high electrical conductivity at room temperature (about 10e3 Sem-'). In the aim of understanding the possible interactions of the mobile ions with polymer or solvent molecules, a comparative Raman study has been carried out on samples containing all the components of the gel electrolytes or some of them. The interaction with Li+ ions induces appreciable modifications of the vibrational spectra of the solvent molecules; two new bands appear at 9OOcm-' and 730cm-', slightly upshifted with respect to the stretching and bending modes of the ethylene carbonate ring. The change in size and polarizability of the anion species does not affect such cation-solvent interaction.
Polymer, 2004
Anisotropic polymer composites with fixed, oriented liquid crystalline organisation prepared by in situ photopolymerisation of acrylic or methacrylic acids in several cellulose derivatives were investigated by low frequency Raman scattering. The results were interpreted basing on a model of non-continuous structure of polymer glasses. The Raman investigations have shown that the macromolecules of the nonmesogenic (acrylic) component are oriented in the anisotropic composites, and that the orientation of the polyacrylic chains is more pronounced in the composites with higher concentration of the liquid crystalline cellulose derivative. It was found, that the interactions between the components play a crucial role in the formation of the composites (template-like photopolymerisation) and they determine their supramolecular structure. The liquid crystalline cellulose derivatives able to form hydrogen bonds play a role of specific cross-linking agents, while the cellulose derivatives with aliphatic side chains work as plasticisers. q
Interaction of Hydrophobically Modified Poly(acrylic acid) Hydrogels with Ionic Surfactants
Macromolecules, 1996
The role of the hydrophobic effect in polyelectrolyte gel/ionic surfactant interactions was investigated. A series of hydrophobically modified poly(acrylic acid) gels with well-controlled hydrophobicity was synthesized by free-radical copolymerization of acrylic acid with n-alkyl acrylates (n ) 8, 12, and 18) in the presence of a cross-linking agent. The interaction of the gels with ionic surfactantssNcetylpyridinium chloride and sodium dodecylbenzenesulfonateswas studied. Four gel/surfactant combinations were considered: uncharged gel/cationic surfactant, uncharged gel/anionic surfactant, anionic gel/ cationic surfactant, and anionic gel/anionic surfactant. It was shown that the gels absorb cationic surfactant ions via an ion-exchange reaction with network counterions. On the other hand, the absorption of anionic surfactant is governed primarily by hydrophobic interactions, and hence, due to conditions of electroneutrality, anionic surfactant penetrates the gel together with corresponding co-ions. Therefore, the uptake of cationic surfactant ions results in gel shrinkage, while the uptake of anionic surfactant induces gel swelling. In the anionic gel/anionic surfactant system, a significant interaction is observed only for the most hydrophobic gels when hydrophobic interactions overcome the electrostatic repulsion between similarly charged groups.
Polymer, 2000
The low-frequency Raman scattering (LFRS) was used in order to determine the orientation of poly(acrylic acid) in anisotropy composite with liquid crystalline [(propionyloxy)propyl]cellulose (PPC). The photopolymerisation of acrylic acid in the presence of PPC leads to the formation of the poly(acrylic acid) (pAA) anisotropic network. This anisotropy is stable even at temperatures higher than the temperature of the optical isotropisation of the PPC/pAA composite. The comparison of the LFRS and thermooptical data proves the hypothesis explaining of the reversibility of the optical birefringence in the PPC/pAA composites by formation, in a course of photopolymerisation of anisotropic pAA network. á§