Development of a Model for Analyzing the Swelling Rate of Ionic Gels on the Basis of the Diffusion of Mobile Ions: Application to the pH-Sensitive Swelling of a Polyelectrolyte Complex Gel Prepared from Xanthan and Chitosan

Chu, Chia-Hong; Kumagai, Hitoshi; Sakiyama, Takaharu; Ikeda, Shinya; Nakamura, Kozo

doi:10.1271/bbb.60.1627

Cited by 13 publications

(3 citation statements)

References 10 publications

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“…For polyelectrolytes with acidic or basic groups, the pH of the surrounding medium is another important factor because it affects their degrees of ionization and thus charge densities. Several studies have been performed to analyze the effects of polyelectrolyte charge density on the formation, structure, and composition of PECs. − The studies have shown that polyelectrolytes with similar charge densities form densely structured PECs whereas polyelectrolytes with dissimilar charge densities form highly swellable PECs with lower structural densities. , These findings are in agreement with the results of numerous studies on the pH-sensitive swelling behavior of PECs involving polyacids and polybases. − PEC swelling upon changes in pH is due to changes in the charge stoichiometry of the PEC, resulting from changes in the degrees of ionization of the polyelectrolytes. PECs with a stoichiometric charge ratio are more densely structured than PECs with a nonstoichiometric charge ratio, but because they have no net charge they are prone to aggregation, whereas PECs with a nonstoichiometric charge ratio are charge stabilized.…”

Section: Introductionsupporting

confidence: 77%

Effects of pH and Salt Concentration on the Formation and Properties of Chitosan–Cellulose Nanocrystal Polyelectrolyte–Macroion Complexes

2011

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This study examines the effects of pH and salt concentration on the formation and properties of chitosan− cellulose nanocrystal (CNC) polyelectrolyte−macroion complexes (PMCs). The components' pK values, determined by potentiometric titration, were 6.40 for chitosan and 2.46 for the CNCs. The turbidity of PMC particle suspensions was measured as a function of chitosan−CNC ratio, pH, and salt concentration. The maximum turbidity values in titrations of a chitosan solution with a CNC suspension and vice versa occurred at charge ratios of 0.47 ± 0.11 (SO 3 − /NH 3 + ) and 1.16 ± 0.06 (NH 3 + /SO 3 − ), respectively. A pH increase caused a turbidity decrease due to shrinking of the PMC particles upon changes in their components' degrees of ionization. An increase in salt concentration caused a decrease in turbidity due to charge-screening-related shrinking of the PMC particles. The effects of pH and salt concentration on particle size were confirmed by scanning electron microscopy.

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Section: Introductionsupporting

confidence: 77%

Effects of pH and Salt Concentration on the Formation and Properties of Chitosan–Cellulose Nanocrystal Polyelectrolyte–Macroion Complexes

2011

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“…Chitosan in neutral medium has neither free negative charges of the polyacid, nor free positive charges of the ammonium groups. So, this leads to decrease the entry of water and decrease swelling (Chu et al, 1996).…”

Section: Water Uptakementioning

confidence: 99%

Development and characterization of sponge-like acyclovir ocular minitablets

Refai

Tag

2010

Drug Delivery

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“…The speed of volume changes are essentially a function of the effector diffusion into the gels, as described by Fick's laws. It has been shown that expansion of xanthan-chitosan-derived gels upon pH changes seems to be mainly controlled by the diffusion of mobile ions, except that at pH values below 10 the degree of ionization during swelling also may affect the swelling rate [ 55 , 56 ]. Figure 2 illustrates that with the PMMA derived polymer I the kinetics of both expansion and the fully reversible contractions follow pseudo first–order equations, the same holds for the corresponding ab- and desorption of the effectors [ 39 ].…”

Section: Kinetics Concentration Effects and Sensitivitymentioning

confidence: 99%

Chemomechanical Polymers as Sensors and Actuators for Biological and Medicinal Applications

Schneider

Katō

Strongin

2007

Sensors

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Changes in the chemical environment can trigger large motions in chemomechanical polymers. The unique feature of such intelligent materials, mostly in the form of hydrogels, is therefore, that they serve as sensors and actuators at the same time, and do not require any measuring devices, transducers or power supplies. Until recently the most often used of these materials responded to changes in pH. Chemists are now increasingly using supramolecular recognition sites in materials, which are covalently bound to the polymer backbone. This allows one to use a nearly unlimited variety of guest (or effector) compounds in the environment for a selective response by automatically triggered size changes. This is illustrated with non-covalent interactions of effectors comprising of metal ions, isomeric organic compounds, including enantiomers, nucleotides, aminoacids, and peptides. Two different effector molecules can induce motions as functions of their concentration, thus representing a logical AND gate. This concept is particularly fruitful with effector compounds such as peptides, which only trigger size changes if, e.g. copper ions are present in the surroundings. Another principle relies on the fast formation of covalent bonds between an effector and the chemomechanical polymer. The most promising application is the selective interaction of covalently fixed boronic acid residues with glucose, which renders itself not only for sensing, but eventually also for delivery of drugs such as insulin. The speed of the responses can significantly increase by increasing the surface to volume ratio of the polymer particles. Of particular interest is the sensitivity increase which can be reached by downsizing the particle volume.

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Development of a Model for Analyzing the Swelling Rate of Ionic Gels on the Basis of the Diffusion of Mobile Ions: Application to the pH-Sensitive Swelling of a Polyelectrolyte Complex Gel Prepared from Xanthan and Chitosan

Cited by 13 publications

References 10 publications

Effects of pH and Salt Concentration on the Formation and Properties of Chitosan–Cellulose Nanocrystal Polyelectrolyte–Macroion Complexes

Effects of pH and Salt Concentration on the Formation and Properties of Chitosan–Cellulose Nanocrystal Polyelectrolyte–Macroion Complexes

Development and characterization of sponge-like acyclovir ocular minitablets

Chemomechanical Polymers as Sensors and Actuators for Biological and Medicinal Applications

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