Semidilute solutions of poly(methacrylic acid) in the absence of salt: Dynamic light-scattering study

Sedlák, Marián; Koňák, Čestmı́r; Štěpánek, Petr; Jakeš, J.

doi:10.1016/0032-3861(87)90156-x

Cited by 110 publications

(119 citation statements)

References 31 publications

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“…17 Dynamic light scattering (DLS) studies on polyelectrolytes in the absence of salt or at low ionic strength show, in general, the existence of a bimodal time distribution behavior, corresponding to the existence of a fast and a slow relaxation mode. Such observations have been reported for different charged macromolecular systems, including synthetic [18][19][20][21][22] and biological polyelectrolyte solutions. [23][24][25] The fast mode is often interpreted as a process involving the diffusion of single polyions.…”

Section: Introductionsupporting

confidence: 59%

Dynamic light scattering and viscosimetry of aqueous solutions of pectin, sodium alginate and their mixtures: effects of added salt, concentration, counterions, temperature and chelating agent

Lima¹,

Soldi²

2009

J. Braz. Chem. Soc.

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Efeitos de adição de sal, concentração, presença de contraíons, temperatura e agente quelante em soluções aquosas de pectina, alginato de sódio e misturas destes foram analisadas por viscosimetria e espalhamento de luz dinâmico (DLS). A viscosidade intrínseca dos sistemas binários diminuiu com a adição de sal e com o aumento da temperatura, porém, mostrou-se insensível à adição de NaEDTA. Como esperado, a viscosidade intrínseca do sistema ternário alginato/pectina/água foi igual a média da viscosidade intrínseca determinada para os sistemas binários. Estudos de DLS indicaram a ocorrência de uma distribuição bimodal (presença dos modos de relaxação rápido e lento) para ambos os sistemas binários e ternários a 25 °C, refletindo um processo de agregação. No caso do modo lento de relaxação, um aumento significativo do raio hidrodinâmico foi observado tanto para os sistemas binários como ternário, na presença de NaCl e KCl a 25 °C. No entanto, a 80 °C, o raio hidrodinâmico correspondente ao modo lento em soluções de KCl foi praticamente constante para todos os sistemas estudados e não foi observado para o sistema binário alginato/solução aquosa.The effects of added salt, concentration, counterions, temperature and chelating agent on aqueous solutions of pectin, sodium alginate and their mixtures were analyzed by viscosimetry and dynamic light scattering (DLS) techniques. The intrinsic viscosity of the binary systems decreased with the addition of salt and with temperature, while it was found to be insensitive to the addition of NaEDTA. As expected the intrinsic viscosity of the ternary alginate/pectin/water system was equal to the average of the intrinsic viscosity for the binary systems. The DLS studies indicated a bimodal distribution (fast and slow relaxation modes) for both binary and ternary systems at 25 °C, reflecting aggregation. A significant increase in the hydrodynamic radius, in the case of the slow mode, was observed for the binary and ternary systems in the presence of NaCl and KCl at 25 °C. However, at 80 °C the hydrodynamic radius for the slow mode in KCl solutions was practically constant for all the studied systems, except for the alginate binary solutions in which were not observed.

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Section: Introductionsupporting

confidence: 59%

Dynamic light scattering and viscosimetry of aqueous solutions of pectin, sodium alginate and their mixtures: effects of added salt, concentration, counterions, temperature and chelating agent

Lima¹,

Soldi²

2009

J. Braz. Chem. Soc.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

The slow relaxation mode: from solutions to gel networks

Ngai

2010

Polym J

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In the past, many laser light-scattering experimental results revealed that besides the fast relaxation mode, there existed an additional slow mode in semidilute solutions. This slow mode has been assigned to a variety of origins, but there has been no clear and well-accepted explanation. As the polymer concentration increases, the slow relaxation mode persists in the concentrated region, in melts and in gels in which polymer chains are crosslinked instead of entangled. The slow relaxation mode has also been reported for charged macromolecules in aqueous and nonaqueous solutions. However, it is generally thought to be different in nature from that observed in semidilute neutral polymer solution. In recent years, armed with novel solution preparation methods and some specially designed polymers, we have reexamined the dynamics of polymer chains, especially the slow mode, in semidilute neutral polymer solutions, dilute polyelectrolyte solutions and gels, which are reviewed here. Our results suggest that the slow mode can be qualitatively considered as hindered motions of interacting chains even though the nature of interaction can be very different; namely, from the weak segment-segment interaction in a less good solvent to strong electrostatic interaction among polyelectrolyte chains, and even to chemical crosslinking inside gel networks.

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“…Currently, DLS is used on a routine basis for the analysis of particle sizes in the sub micrometer range; it provides an estimation of the average size and its distribution within a measuring time of a few minutes. However, improvements in the ability to model dynamic behavior and relate it to scattering data has continued to make it a useful tool to study slow effects such as swelling mechanisms and phase transitions [117][118][119][120][121][122][123][124][125][126][127]. Still, XPCS is considered superior to DLS in certain situations because 1) it enables high-q dynamics and 2) it can probe samples that are opaque or subject to multiple light scattering phenomena under DLS conditions.…”

Section: Time-resolved Dynamics With Photon Correlation Spectroscopymentioning

confidence: 99%

Combining theory and experiment for X-ray absorption spectroscopy and resonant X-ray scattering characterization of polymers

Cordova

Brady

2016

Polymer

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An improved understanding of fundamental chemistry, electronic structure, morphology, and dynamics in polymers and soft materials requires advanced characterization techniques that are amenable to in situ and in operando studies. Soft X-ray methods are especially useful in their ability to non-destructively provide material or chemical moiety specific information. Analysis of these experiments, which can be very dependent on X-ray energy and polarization, can quickly become complex. Complementary modeling and predictive capabilities are required to properly probe these critical features. Here, we present relevant background on this emerging suite of techniques. We focus on how the combination of theory and experiment has been applied and can be further developed to drive our understanding of how these methods probe relevant chemistry, structure, and dynamics in soft materials.

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Semidilute solutions of poly(methacrylic acid) in the absence of salt: Dynamic light-scattering study

Cited by 110 publications

References 31 publications

Dynamic light scattering and viscosimetry of aqueous solutions of pectin, sodium alginate and their mixtures: effects of added salt, concentration, counterions, temperature and chelating agent

Dynamic light scattering and viscosimetry of aqueous solutions of pectin, sodium alginate and their mixtures: effects of added salt, concentration, counterions, temperature and chelating agent

The slow relaxation mode: from solutions to gel networks

Combining theory and experiment for X-ray absorption spectroscopy and resonant X-ray scattering characterization of polymers

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