ISSN:
0098-1273
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
A Langevin equation of motion for a charged bead-spring statistical chain is written in difference form and the relaxation and equilibrium behavior of the chain is studied by computer simulation. Results are presented for the behavior of end-to-end length h, principal axes of the polymer ellipsoid L1, L2, L3, and chain contour length c in terms of their averages, root mean square values, root mean square fluctuations, orientations, and relaxation strengths and times. The simulation was made with various sets of parameters, bead number N, charge on the bead q, and radius of ion atmosphere around the bead k-1. It is found that 〈h2〉1/2 and 〈L12〉1/2 increase more strongly with increasing q and decreasing κ than 〈L22〉1/2, 〈L32〉1/2, and 〈c12〉1/2, indicating that the chain is expanded in three dimensions and at the same time is extended along the end-to-end direction. The relaxation time τrot of rotation of the end-to-end vector, which is proportional to N2 at q = 0, increases with increasing q and tends to be proportional to N3 for an extended chain, while the relaxation time τconf of the magnitude of h is almost independent of q and is always proportional to N2. It is concluded that the extended chain possesses a well-defined end-to-end axis and the chain rotates as a whole with a relaxation time τrot which is much longer than τconf. The complex viscosity of the chain is calculated from the Fourier transform of the time-correlation function of momentum flux and is found to have a frequency spectrum similar to that observed for aqueous solutions of poly(acrylic acid). The dominant mode appearing in the low-frequency range is evidenced to arise from the rotation of the extended chain.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1975.180131107
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