Conformational Transition of the Copolymer of Maleic Acid and α-Methylstyrene in Aqueous Solution

Abstract

ABSTRACT:The pH -induced conformational transition of an alternating copolymer of maleic acid and a-methylstyrene in aqueous NaC1 solutions has been investigated by pH-titration, optical, viscometric, and dilatometric measurements. The relation between the intrinsic viscosity and the degree of dissociation of the primary carboxyl group shows a transition from a compact to an extended coil form. The volume change accompanying the transition at 0.009 M NaCl was found to increase from -0.8 cm 3 to 2.2cm 3 per monomole with increasing temperature from 15 to 35°C. All results are compared with those of the maleic acid copolymer with styrene studied previously, and the influence of methyl groups on the transition is discussed.

Conformational Characterization of A Maleic Acid Copolymer with An Inflexible Side Chain

“…The degree of polymerization was estimated to be ~ 640 by use of the intrinsic viscosity of the anhydride copolymer in tetrahydrofuran at 30°C r MALEIC ACID COPOLYMER 863 and the MW- [JJ] relationship for the maleic anhydride-styrene copolymer [20]. Aqueous NaCl solutions of (MA-Ind) n were prepared by the method described previously [11][12][13][14][15][16][17][18].…”

“…Potentiometric, viscometric, and optical titration data were obtained by using the same methods as in our previous studies on maleic acid copolymers [11][12][13][14][15][16][17][18]. The concentrations of (MA-Ind),, used were approximately 1.0 X 10" 2 , 1.8 X 10" 2 , and 1.6 X 10" 3 monomol/dm 3 for pH, viscometric, and optical measurements, respectively.…”

“…Figure 1 shows the modified pH-titration curves at four Fs in terms of a, the degree of ionization of whole carboxyl groups. We previously expressed the pH-titration results of maleic acid copolymers with a, [11][12][13][14][15][16][17][18], because almost all the maleic acid copolymers studied have showed the transition within the ionization ranges of primary carboxyl groups. However, Minakata et al analyzed the pH-titration curves of maleic acid copolymers, including (MA-Ind),,, in terms of a [23][24][25][26].…”

“…The hydrophobic polyacids studied previously are maleic acid copolymers of hydrophobic vinyl compounds. Strauss et al [2][3][4][5][6][7][8][9][10] studied the transition of copolymers with longer alkyl vinyl ethers than propyl, and our group [11][12][13][14][15][16][17][18] has studied aromatic vinyl compounds such as styrene. The side chains in the alkyl vinyl ether copolymers are flexible in the coiled form, and even the side chains of our aromatic copolymers were found to be flexible according to NMR measurements [17].…”

Conformational studies on poly(ethacrylic acid) in aqueous salts by potentiometric, viscometric, optical and1H-NMR measurements

“…Methods of the potentiometric, viscometric and optical titrations were previously described [7,9,23]. IH-NMR spectra were obtained by a 400 MHz 1H-NMR spectrometer, JEOL FX-400.…”