title: Roles of hydrophobic interaction in a volume phase transition of alkylacrylamide gel induced by the hydrogen-bond-driving alkylphenol binding.
abstract: It was found that a degree of the binding of alkylphenols to N-alkylacrylamide gel increased transitionally to induce the volume phase transition of gel. Binding isotherms of nonylphenol (n-Ph), propylphenol (p-Ph), ethylphenol (e-Ph), methylphenol (m-Ph), and phenol (Ph) to N-isopropylacrylamide (NIPA), N,N-diethylacrylamide (DEA), N,N-dimethylacrylamide (DMA), and acrylamide (AM) gels were examined. Two types of binding, the site binding at beta < 1 and the multimolecular binding at beta > 1, were observed, where beta was a degree of binding to a monomeric unit of the chain. The former binding was analyzed with the Hill equation applicable to the cooperative binding and the latter binding with the Brunauer-Emmett-Teller (BET) equation applicable to the multilayer adsorption. The binding constant, K, and the Hill coefficient, N, decreased and increased, respectively, in the order of DEA, NIPA, and DMA gels in the case where the binding alkylphenol was the same. The K value increased in the order of Ph, m-Ph, e-Ph, p-Ph, and n-Ph that bound to the same type of gel. The N value was found to change little with the type of binding alkylphenol. The complexes of N-alkylamide with alkylphenol were condensed to form the ordered nanostructures that were observed as broad scattering peaks in small-angle X-ray scattering experiments. The fluorescence excimer emission was observed for the phenol-binding DMA gel, which corresponded to the condensed state of phenol.
authors.affiliation: Department of Chemistry, Faculty of Science, Kyushu University, 33 Hakozaki, Higashiku, Fukuoka 812, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kawashima
authors.forename: Shogo
authors.initials: S
authors.lastname: Koga
authors.forename: Masahiko
authors.initials: M
authors.lastname: Annaka
authors.forename: Shigeo
authors.initials: S
authors.lastname: Sasaki
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D001665:Binding Sites; D005782:Gels / Q000737:chemistry; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D033363:Neutron Diffraction; D010316:Particle Size; D044367:Phase Transition; D010636:Phenols / Q000737:chemistry*; D053838:Scattering, Small Angle; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D000178:Acrylamides; D005782:Gels; D010636:Phenols