Kinetic Studies on the Conformational Transition of the Copolymer of Styrene and Maleic Acid in Aqueous Salt Solution

Sugai, Shintaro; Ohno, Nobumichi; Nitta, Katsutoshi

doi:10.1021/ma60042a056

Cited by 25 publications

(22 citation statements)

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“…The entrance rate constants of neutral arenes to micelles are in the range of (5-8) × 10 9 M -1 s -1 . 28 Thus, this entry time is beyond the time resolution Py + C-COOH S (Py‚‚‚C-COOH) (14) of the stopped-flow equipment. However, at higher concentration of pyrene (5 µM) a slow increase of emission intensity is observed when a PMA solution at pH 3.8 (below the transition) and an aqueous solution of pyrene are mixed.…”

Section: Resultsmentioning

confidence: 99%

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Effect of the Molecular Weight on the Dynamics of the Conformational Transition of Poly(methacrylic acid)

1999

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Stop flow pH jump experiments were carried out on poly(methacrylic acid), PMA, solution of various molecular weights. The fluorescence changes of the probe pyrene, which can locate in the hydrophobic PMA coil or in the aqueous phase, were used to monitor pH-induced events in the PMAwater system. At least two well-separated time regions for the pH-induced conformational change of PMA were observed: one with τ ) 1-2 s and another with τ ) 50-100 s. A theoretical model to quantitatively explain the observed kinetic changes is given. This is based on a model developed by Schwarz for the helix-coil transition of polypeptides and can be briefly described as follows. Any configuration of the polymer is characterized by a statistical distribution of segments in polar and hydrophobic regions. Then a conformational transition involves the change of a number of segments from one state to the another, and its kinetics corresponds to a relaxation process with the pH jump as the initial perturbation. Several details pertinent to unambiguous interpretation are also described briefly. This includes the rate of neutralization of the acid groups on PMA and the rate of solution of small pyrene crystals in a colloidal system. The above confusing effects were established and thus could be avoided in the actual pH-induced conformational changes of PMA.

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Section: Resultsmentioning

confidence: 99%

“…1,14,15 In this model, the transition is described as occurring between two forms, A and B, in which the polymer subunits may exist. At low values of R the form A dominates, and after passing the transition region the B form will occur predominantly.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Molecular Weight on the Dynamics of the Conformational Transition of Poly(methacrylic acid)

1999

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“…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].…”

Section: Methodsmentioning

confidence: 99%

“…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].…”

Section: Introductionmentioning

confidence: 99%

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

Ohno¹,

Sugai²

1990

Journal of Macromolecular Science: Part A - Chemistry

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Viscometric, pH, optical, and calorimetric titration studies of an alternating copolymer of maleic acid and indene in aqueous NaCl of 0.01 to 0.27 Mat 15 to 35°C showed the conformational transition of a compact to an expanded coil upon ionization of the primary carboxyl groups. The thermodynamic parameters of the transition were calculated. The results indicate that the bulky and inflexible side chain in indene sterically interferes with the formation of the compact form of the copolymer, but stabilizes the low entropic hydrophobic region. fPresent address: Institute of Life Sciences, Soka University, Tangi-m chi 1-236, Hachioji, Tokyo 192, Japan.

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“…The compact forms of the copolymers are stabilized by hydrophobic interaction between the hydrophobic side chains and the transitions are described in terms of the two-state mechanism. Our conformational studies on the maleic acid copolymers with styrene and a-methyl styrene have indicated existence of phenyl groups buried in the interiors of the compact forms and exposure of them accompanying the transitions [7][8][9][10][11]. The transitions in our maleic acid copolymers have been considered to be the intramolecular events and to be described by the twostate mechanism.…”

Section: Introductionmentioning

confidence: 98%

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

Sugai

Nitta

Ohno³

et al. 1983

Colloid & Polymer Sci

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Abstract:The conformation of poly(ethacrylic acid) was studied in aqueous salts by means of potentiometric, viscometric, optical and iH-NMR measurements. The modified potentiometric titration curves in aqueous NaC1 at ionic strengths 0.01 -0.3 and 5-35 ~ indicated the pH-induced conformational transition from the compact to extended coil. The standard free energy changes and the difference in molar heat capacity between the two conformers were estimated from the potentiometric data. The viscometric and optical behaviours did also show the existence of the compact form at acid pH's and the pHinduced conformational transition to the extended coil in aqueous NaC1 and NaC10 4. From comparison with the data for poly(methacrylic acid), the results were concluded to be consistent with the existence of the compact form stabilized by hydrophobic interaction between ethyl groups. The methyl widths in 400 MHz 1H-NMR spectra indicated that the side chains in the polymer in the compact form are in a more restricted motional state than in the coil form. Intermolecular aggregations were found at very low degrees of ionization of carboxyl groups.

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Kinetic Studies on the Conformational Transition of the Copolymer of Styrene and Maleic Acid in Aqueous Salt Solution

Cited by 25 publications

References 1 publication

Effect of the Molecular Weight on the Dynamics of the Conformational Transition of Poly(methacrylic acid)

Effect of the Molecular Weight on the Dynamics of the Conformational Transition of Poly(methacrylic acid)

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

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

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