ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The light scattering function P(aitch-theta) of charged isolated threefold rotational isomeric state model polymers was simulated by Metropolis Monte Carlo in the Debye–Hückel approximation. Number of chain units N (up to 250), and ratio (from 0.5 to 64) of Debye screening length κ−1 to bond length D were varied at a bond angle θ of 90°; θs of 70° and 45° were also investigated. Charge was fixed by setting the "Manning parameter'' to 1. Because the properties of linear polyelectrolytes have been interpreted in terms of electrostatic excluded volume and electrostatic persistence lengths, similar chains with hard sphere repulsion were simulated, up to N=400, as were nearly wormlike chains with no repulsion. Overall, a function suggested by Noda et al. described the P(aitch-theta) of both hard sphere chains and electrostatic repulsion chains with κ−1/D of 0.5 moderately well. However, first order renormalization group (RG) calculations correctly predict an intersection between this P(aitch-theta) and that for Gaussian random coils, while the Noda et al. function does not. Requirements for experimental observation of excluded volume effects in polyelectrolytes are discussed. The P(aitch-theta) of chains with large κ−1/D was not fit well by that of nonexcluded volume wormlike chains with the persistence lengths predicted by theory, possibly because excluded volume effects were not small. Linear fits to a log–log plot of 1/P(aitch-theta) vs the square of the scattering vector times the radius of gyration gave the expected slopes, but not intercepts, as predicted by first order RG, probably because u was not large enough.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.463496
