Reference

On the chain length dependence of the dynamics of coil expansion of poly(methacrylic acid)

On the chain length dependence of the dynamics of coil expansion of poly(methacrylic acid). Irie, Masahiro; Schnabel, Wolfram (Inst. Sci. Ind. Res., Osaka Univ., Osaka 567, Japan). Macromolecules, 19(11), 2846-50 (English) 1986. CODEN: MAMOBX. ISSN: 0024-9297. DOCUMENT TYPE: Journal CA Section: 36 (Physical Properties of Synthetic High Polymers) The rate of chain expansion of poly(methacrylic acid) (I) [25087-26-7] in MeOH solns. contg. 4,4'-bis(dimethylamino)triphenylmethane leucohydroxide (II) [510-13-4] was measured by following the change in the light scattering intensity (LSI). Chain expansion was induced by the photolysis of II by a 20-ns flash of 265-nm light. Hydroxyl ions generated in this way led to an increase in the degree of ionization of I. The half-life of the LSI decreased reflecting the chain expansion depended on the mol. wt. (M0.9) while in the Rouse-Zimm theory M1.5 was obtained. The discrepancy was explained in terms of the neutralization of I being a stepwise noncooperative process. Initially, the OH ions reacted almost exclusively with COOH groups in the outer regions of the rather compact I coils. Subsequently, the ionized sites equilibrated and thus became statistically distributed along the chains.

On the dynamics of coil expansion of poly(methacrylic acid) induced by rapid neutralization

On the dynamics of coil expansion of poly(methacrylic acid) induced by rapid neutralization. Irie, Masahiro; Schnabel, Wolfram (Inst. Sci. Ind. Res., Osaka Univ., Osaka, Japan). Makromol. Chem., Rapid Commun., 5(7), 413-17 (English) 1984. CODEN: MCRCD4. ISSN: 0173-2803. DOCUMENT TYPE: Journal CA Section: 36 (Physical Properties of Synthetic High Polymers) Section cross-reference(s): 67 When poly(methacrylic acid) (I) [25087-26-7] (mol. wt. 96,000 and 1,300,000) in MeOH contg. (4-Me2NC6H4)2C(OH)Ph [510-13-4] was irradiated (wavelength >270 nm), a reversible decrease in reduced sp. viscosity indicated the expansion of I coils owing to a light-induced increase in OH- concn. Detn. of the rate of conformational change by flash laser photolysis (wavelength 265 nm) revealed a fast and slow decrease in light scattering intensity. The rapid mode reflected an increase in absorption by dye cations and in the n increment of I. The slow mode (half-life 10-30 ms) resulted from coil expansion of I following neutralization, and was strongly suppressed by 0.001 M LiBr. The elec. cond. also decreased slightly after irradn., owing to conversion of OH- to less mobile I anions.