Kinetics of chain aggregation of poly(methyl methacrylate) in isoamyl acetate

Nakata, Mitsuo; Nakagawa, Tomohide; Nakamura, Yoshiki; Wakatsuki, Syogo

doi:10.1063/1.477994

Cited by 17 publications

(15 citation statements)

References 14 publications

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“…[10][11][12] The kinetics of coil-to-globule transition of PMMA in isoamyl acetate was recently studied by static light scattering measurements by Nakata and co-workers. 23,24 These authors started to observe the dimensions of the collapsing chains 30 min after quenching. Since at that time the PMMA coil was already collapsed to a globular form, we believe they measured only the kinetics of aggregation.…”

Section: Discussionmentioning

confidence: 99%

Kinetics of Coil−Globule Collapse in Poly(methyl methacrylate) in Dilute Solutions below ϑ Temperatures

et al. 1999

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The time dependence of coil−globule collapse in atactic poly(methyl methacrylate) samples having molecular weights 6.5 × 106 and 3.3 × 106 g/mol dissolved in isoamyl acetate and n-butyl chloride were studied by dynamic light scattering. For example, a dilute solution of PMMA (6.5 × 106 g/mol) in isoamyl acetate was quenched from 61 °C (ϑ temperature) to 18.5 °C. As a result, the measured hydrodynamic radius (〈R h〉) was reduced from 42 ± 2 to 15 ± 2 nm. For the cells used in these DLS measurements the thermal equilibration time was found to be about 20 s. The transition from coil to globule in this cell was observed to take place in almost 35 s. We have found the coil-to-globule transition time to be inversely related to the depth of quench (ΔT) of the process. This transition time also increases with increase in molecular weight of the polymer chain.

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Section: Discussionmentioning

confidence: 99%

Kinetics of Coil−Globule Collapse in Poly(methyl methacrylate) in Dilute Solutions below ϑ Temperatures

et al. 1999

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“…[138,139] These authors also investigated the kinetics of chain aggregation of PMMA in the same solvents. [140][141][142] Since the dilute solutions of PMMA in these solvents indicate very slow phase separation, SLS measurements could be carried out for 30 min after quenching to low temperatures and the mean-square radius of gyration hs 2 i was determined from the y-temperature to relatively low collapsing temperatures. Nakata and coworkers interpreted their coil-globule transition of chain collapse processes at various temperatures by plotting the square of the expansion factor values (a 2 ) as a logarithmic function of time (ln t).…”

Section: Experimental Studies Of the Kinetics Of Polymer Collapsementioning

confidence: 99%

Coil‐Globule Collapse in Flexible Macromolecules

Baysal

Karasz

2003

Macro Theory & Simulations

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The transition of a solvated flexible macromolecular chain from random coil behavior in the θ‐state to a globular compact form in the collapsed state has been the subject of extensive theoretical and experimental studies. Most of the coil‐globule transition studies of macromolecules have concentrated on the prototypical polystyrene‐cyclohexane system. However, chain contractions reported in this system have been around 75% of those in the unperturbed θ‐state. This relatively small decrease in size does not satisfy the criterion for a densely packed, collapsed globule. Experimentally, the collapse from a coil to a true compact globular state has now been established for two flexible macromolecules: poly(N‐isopropylacrylamide) in water and poly(methyl methacrylate) in various solvents. In this contribution, we review recent theoretical studies covering phenomenological and Langevin models as well as computer simulations. In addition, we outline recent experimental studies of the coil‐globule transition of various flexible polymers, copolymers, and polyelectrolytes.Expansion factor, α, versus temperature for NaPSS in 4.17 M aqueous NaCl solution. (•): NaPSS‐1, (○): NaPSS‐2.imageExpansion factor, α, versus temperature for NaPSS in 4.17 M aqueous NaCl solution. (•): NaPSS‐1, (○): NaPSS‐2.

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“…The contraction process was caused by a conformational change of PNIPAM chains at the interface and compared with a computer simulation. 29 Previously, we studied the processes of the chain collapse 38 and chain aggregation 39,40 for dilute solutions of poly(methyl methacrylate) in isoamyl acetate by static light-scattering experiments. For M w × 10 -6 ) 8.4 and 12.2, we determined the mean-square radius of gyration 〈s 2 〉 of the polymer chain as a function of time after the quench of solution.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the Coil−Globule Transition of Poly(methyl methacrylate) in a Mixed Solvent

2001

Self Cite

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The coil-globule transition and chain collapse process were studied for poly(methyl methacrylate) in the mixed solvent tert-butyl alcohol + water (2.5 vol %) by static light-scattering measurements. The expansion factor R 2 for the mean-square radius of gyration was obtained as a function of time for various molecular weights. For the molecular weights Mw × 10 -6 ) 1.57, PMMA chains collapsed to an equilibrium globule within 30 min after quench. For Mw × 10 -6 ) 4.0 and 12.2, chain collapse processes were observed for time periods of hours and days, respectively. The time dependence of the observed expansion factor was represented by the stretched exponential formwhere R 2 ∞ is the equilibrium expansion factor sufficiently long time after quench. β was obtained in the range from 0.1 to 0.4 and decreased with decreasing temperature and increasing molecular weight. From the behavior of β, the stretched exponential process was suggested to be intrinsic to each polymer chain rather than due to a superposition of exponentially collapse processes of polymer chains with various decay times. The equilibrium expansion factor obtained as a function of temperature and molecular weight was represented by the theoretical prediction R 3 -R -C(R -3 -1) ) B(1θ/T)M 1/2 . The constants B and C were determined to be B ) 0.0164 and C ) 0.049 independent of the molecular weight.

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Kinetics of chain aggregation of poly(methyl methacrylate) in isoamyl acetate

Cited by 17 publications

References 14 publications

Kinetics of Coil−Globule Collapse in Poly(methyl methacrylate) in Dilute Solutions below ϑ Temperatures

Kinetics of Coil−Globule Collapse in Poly(methyl methacrylate) in Dilute Solutions below ϑ Temperatures

Coil‐Globule Collapse in Flexible Macromolecules

Kinetics of the Coil−Globule Transition of Poly(methyl methacrylate) in a Mixed Solvent

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