Coil-globule transition of poly(methyl methacrylate) in isoamyl acetate

Nakata, Mitsuo; Nakagawa, Tomohide

doi:10.1103/physreve.56.3338

Cited by 43 publications

(64 citation statements)

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“…The experimental picture is not clear because of difficulties due to the competition between the collapse of the individual chains and the aggregation of different ones. As a result, there have been only few experimental studies of the kinetics of collapse of isolated chains [5][6][7]. Theoretical studies have utilized a variety of approaches in focusing on different aspects of the problem.…”

Section: Introductionmentioning

confidence: 99%

Early stages of homopolymer collapse

2000

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Interest in the protein folding problem has motivated a wide range of theoretical and experimental studies of the kinetics of the collapse of flexible homopolymers. In this Paper a phenomenological model is proposed for the kinetics of the early stages of homopolymer collapse following a quench from temperatures above to below the θ temperature. In the first stage, nascent droplets of the dense phase are formed, with little effect on the configurations of the bridges that join them. The droplets then grow by accreting monomers from the bridges, thus causing the bridges to stretch. During these two stages the overall dimensions of the chain decrease only weakly. Further growth of the droplets is accomplished by the shortening of the bridges, which causes the shrinking of the overall dimensions of the chain. The characteristic times of the three stages respectively scale as N 0 , N 1/5 and N 6/5 , where N is the degree of polymerization of the chain.

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Section: Introductionmentioning

confidence: 99%

Early stages of homopolymer collapse

2000

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“…A transition of single polymer chain induced by the solvent quality change, known as a coilglobule transition, has been extensively studied because of their importance in not only polymer physics but also application aspects for the collapse of a gel network, the folding of a protein, and so on. [1][2][3][4][5][6] Poly(N-isopropylacrylamide) (PNiPAM) chain in water has a Θ temperature at 30.6°C, where the second virial coefficient is zero, and shows the coil-globule transition by heating. Indeed, there are many reports studying PNiPAM solutions by scattering methods, 7-10 fluorescence, 11 electronic paramagnetic resonance, 12 IR spectroscopy, 13,14 and calorimetry.…”

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Soret Coefficient of Poly(N-isopropylacrylamide)/Water in the Vicinity of Coil−Globule Transition Temperature

Kita

Wiegand

2005

Macromolecules

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According to thermodynamics of polymer solutions, polymers show conformational changes depending on the solvent quality. A transition of single polymer chain induced by the solvent quality change, known as a coilglobule transition, has been extensively studied because of their importance in not only polymer physics but also application aspects for the collapse of a gel network, the folding of a protein, and so on. [1][2][3][4][5][6] Poly(N-isopropylacrylamide) (PNiPAM) chain in water has a Θ temperature at 30.6°C, where the second virial coefficient is zero, and shows the coil-globule transition by heating. Indeed, there are many reports studying PNiPAM solutions by scattering methods, 7-10 fluorescence, 11 electronic paramagnetic resonance, 12 IR spectroscopy, 13,14 and calorimetry. 15,16 A considerable amount of work on PNiPAM solutions is collected in a review. 17 However, thermal diffusion phenomena, also called the Ludwig-Soret effect, have not been studied with taking into account the coil-globule transition in the vicinity of the Θ temperature.The Ludwig-Soret effect accounts for a mass flux, J 1 , in a mixture which is induced by a temperature and a concentration gradient. [18][19][20][21] Under a steady temperature gradient a steady concentration gradient is built up, where the flux vanishes (J 1 ) 0). The Soret coefficient, S T , is expressed as where D is the translational mass diffusion coefficient, D T the thermal diffusion coefficient, c 1 the mass fraction of component 1, and T the temperature.The sign of S T indicates whether component 1 migrates to the warm side or the cold side of the fluid. 22 If the system is dominated by short-range interactions, the thermal diffusion behavior can be attributed to single particle and collective contributions. 23 There are several detailed and systematic studies of thermal diffusion phenomena of organic polymer systems covering scaling behavior, concentration effects, and preferential solvation effects in mixed solvents. [24][25][26][27][28][29] In contrast to those organic systems, there are only few studies for aqueous polymer solutions.Observations of the Ludwig-Soret effect in the vicinity of coil-globule transition of PNiPAM/water will illuminate the importance of segment-segment and segment-solvent interactions. These key features can be varied experimentally according to the consequence of coil-globule transition of PNiPAM. This approach will lead to deeper understanding of thermal diffusion behavior of aqueous polymer systems as well as provide new insight into the solution properties of PNiPAM in a thermodynamically nonequilibrium state.PNiPAM was purified by a fractionation method. 8 One fraction was used in this study which had the weightaveraged molecular weight M w ) 3.0 × 10 6 g/mol with a polydispersity M w /M n of 1.20. Details of sample preparation and characterizations are described elsewhere. 30 Water was deionized by a Milli-Q system. In this study 1.0 g/L PNiPAM in water was prepared with a tiny amount of the dye, Basantol Yellow 215. 31 ...

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“…These values agree with those obtained at the temperature. 1,4 Thus, the temperature for PMMA in pure tert-butyl alcohol can be determined to be 66.0°C, which is 24.5°C higher than the temperature 41.5°C for PMMA in the mixed solvent tert-butyl alcohol ϩwater͑2.5 vol %͒. 4 Figure 4 shows plots of the expansion factor ␣ 2 vs the time ͑min͒ at various temperatures for M w ϭ1.22ϫ10 7 .…”

Section: Resultsmentioning

confidence: 99%

“…These coefficients were determined to be Bϭ0.0041 and Cϭ0.073 for PMMA in isoamyl acetate 1,2 and Bϭ0.0164 and Cϭ0.049 in the mixed solvent tert-butyl alcoholϩwater͑2.5 vol %͒. 3,4 The coil-globule transition has been studied for some other polymer solutions, for which light scattering measurements have been carried out for very large molecular weights and at extremely low concentrations in order to minimize the effect of the phase separation.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4] Since the solutions underwent very slow phase separation, the mean square radius of gyration ͗s 2 ͘ of PMMA chains was determined accurately in the temperature ranges from the temperature 61.0°C to 0°C in isoamyl acetate 1,2 and from the temperature 41.5°C to 20°C in the mixed solvent 3,4 by using solutions in the concentration range of 0.7ϫ10 Ϫ4 -5ϫ10 Ϫ4 g/cm 3 . PMMA chains in both of the solvents collapsed completely before the onset of phase separation.…”

Section: Introductionmentioning

confidence: 99%

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Solvent effect on single-chain collapse of poly(methyl methacrylate) in tert-butyl alcohol

Nakamura

Sasaki

Nakata

2003

The Journal of Chemical Physics

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Kinetic and static properties of the coil-globule transition of poly͑methyl methacrylate͒ ͑PMMA͒ in pure tert-butyl alcohol were determined by static light scattering and compared with those of PMMA in the mixed solvent tert-butyl alcoholϩwater͑2.5 vol %͒ in order to examine the effect of water on the chain collapse. The measurements were carried out for the molecular weight M ϫ10 Ϫ6 ϭ4.1 and 12.2 in the concentration range of 0.6ϫ10 Ϫ4 -2.6ϫ10 Ϫ4 g/cm 3 , and the mean-square radius of gyration ͗s 2 ͘ was determined as a function of the time after an abrupt decrease of temperature.PMMA chains collapsed to equilibrium globules within 90 min after quenching for M ϭ1.22 ϫ10 7 and within 30 min for M ϭ4.1ϫ10 6 . Chain aggregation due to phase separation became noticeable after the collapse of the chain because of an increase of observed molecular weight. For PMMA in the mixed solvent tert-butyl alcoholϩwater͑2.5 vol %͒, the chain collapse process has been observed for periods from hours to weeks depending on the molecular weight and temperature, and the chain aggregation was negligibly small in the chain collapse process. The expansion factor ␣ 2 ϭ͗s 2 ͘/͗s 2 ͘ 0 obtained for fully collapsed chains in pure tert-butyl alcohol was represented by the theoretical prediction ␣ 3 Ϫ␣ϪC(␣ Ϫ3 Ϫ1)ϭB(1Ϫ /T)M 1/2 with the coefficients of Bϭ0.0179 and Cϭ0.054. For PMMA in the mixed solvent, the coil-globule transition curve has been expressed by the same equation with Bϭ0.0164 and Cϭ0.049, close to the above values. The small amount of water in the mixed solvent caused a drastic slowdown in the chain-collapse rate but had little effect on the coil-globule transition curve.

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Coil-globule transition of poly(methyl methacrylate) in isoamyl acetate

Cited by 43 publications

References 32 publications

Early stages of homopolymer collapse

Early stages of homopolymer collapse

Soret Coefficient of Poly(N-isopropylacrylamide)/Water in the Vicinity of Coil−Globule Transition Temperature

Solvent effect on single-chain collapse of poly(methyl methacrylate) in tert-butyl alcohol

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