On the electrostatic contribution to the persistence length of flexible polyelectrolytes

Abstract

Fetters, L. J., unpublished results). Thus, the parameter ( R 2 ) / M was corrected to 75 "C and Tg + 100 "C. A similar change in ( R 2 ) / M for the two above temperatures was not done for PDMB since both theory and experiment indicate that d In (R2)/dT for sterreoirregular polydienes is ca. 0, e.g., see: Mays, J. W.; Hadjichristidis, N.; Graessley, W. W.; Fetters, L. The length b can be estimated from b2 = (R2)/N where N is the number of repeat units per chain. ABSTRACT Quasi-elastic light scattering methods were used to study the dynamics of dilute solutions of high molecular weight (Mp = lo7 daltons) poly(acry1ate) for [ K C l ] a = 0.00,0.05, and 0.10 M. The correlation functions were analyzed by a third-order cumulant and an overlay histogram with exponential sampling methods of analysis. The histograms exhibited a bimodal distribution. It is argued that the fast mode evident in the histograms is associated with the pure translational diffusion process for PAA-K and that the slow mode may be associated with hindered diffusion through cages formed by neighboring polyions. The ionic strength dependence of the translational diffusion coefficient is interpreted in terms of a minor increase in both the excluded-volume parameter and the persistence length, where these parameters eventually reach a limiting value as the ionic strength is lowered. The failure of the current theoretical models of the electrostatic component to adequately describe this ionic strength dependence of the persistence length is discussed in detail.

The slow relaxation mode: from solutions to gel networks

“…Gradually, such two modes have been reported for nearly all charged macromolecules, including both synthetic and biological polyelectrolytes in aqueous and nonaqueous solutions. [76][77][78][79][80][81][82][83][84] Therefore, these two modes are general features of salt-free or low-salt polyelectrolyte solutions. In the past, the fast mode in polymer dilute and semidilute solutions has been attributed to different origins, such as propagation of excitations in a polyelectrolyte pseudolattice or the free diffusion of the noncaged chains/particles.…”

“…It has been attributed to dynamics of large multichain domains (transient aggregates or clusters) formed due to electrostatic interaction [76][77][78][79][80] or some insoluble chain clusters, or even a trace amount of large particles introduced during the imperfect preparation of solution. [89][90][91][92][93] The transient cluster interpretation was supported by studies of poly(styrenesulfonate) with sodium counterions in aqueous solutions under dialysis.…”

“…The interpretation of the slow mode, especially for those very slow relaxation modes observed in salt-free or low-salt polyelectrolyte solutions, is very controversial. [76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95] It has been attributed to large multichain domains formed because of electrostatic interaction or some insoluble clusters or even a trace amount of dust particles introduced during the imperfect preparation of polymer solution. Actually, not everyone accepts or recognized such a slow mode, even though it has been repeatedly observed in many dynamic LLS experiments for more than three decades, because of some problems or questions related to previous light-scattering experiments, such as some earlier premature data analysis methods and the preparation of dust-free viscous solutions.…”

Light Scattering Study of Chitosan in Acetic Acid Aqueous Solutions

“…The large-size mode corresponds to clusters which are the aggregation of several chitosan molecules. The clusters have been observed in most polyelectrolyte solutions, such as t-RNA, [22] DNA, [23] polynucleosome, [24] poly-(acrylic acid), [25] poly(methacrylic acid), [26,27] sodium poly(styrene sulfonate), [28,29] and gelatin. [30] The average hydrodynamic radius and volume fractions of each mode of chitosan in acetic/water solutions with various pH values are summarized in Table 4, in which R h1 and R h2 are the average hydrodynamic radius of primary chitosan molecules and clusters, respectively; V 1 and V 2 are their corresponding volume fractions, respectively.…”

Pressure sensitive adhesives based on interpolymer complexes

“…When polyelectrolytes or ionomers are studied by dynamic light scattering in dilute solution two diffusive relaxation modes are observed, with neither mode representing the diffusion of a single polymer chain. The fast mode is attributed to the coupled diffusion of polyion/counterions[175][176][177][178][179][180][181], while the interpretation of the slow mode has not reached full agreement yet[172,173,176]. Since the slow mode disappears at concentration, the major driving force is attributed to electrostatic interactions.…”