Swelling kinetics of polymers

pH-responsive membranes prepared by treating chitosan (Ch) with glutaraldehyde (GA) or with GA and sulfuric acid (SA) were studied. The structure and properties of the membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis. The effect of the cross-linking process both on the dynamic swelling behaviour of the hydrogel membranes and on the mechanism of water transport through those membranes was investigated in buffer solutions of different pH (1.2-9.5). The mechanism of water transport through the hydrogel chitosan membranes was affected by membrane composition and pH of the swelling medium. Non-cross-linked Ch membrane showed a non-Fickian swelling behaviour in the pH range 6.5-9.5. Chitosan membrane cross-linked with GA (Ch/GA) showed less-Fickian or Fickian swelling behaviour in all buffer solutions. In the case of chitosan membrane cross-linked with GA and SA (Ch/GA/SA), at low pH (lower than the pK a of the hydrogel) the water transport was controlled more by polymer relaxation than by penetrant diffusion. The experimental data clearly suggested that the swelling process in all buffer solutions obeyed second-order kinetics. Values of an apparent swelling rate constant for Ch/ GA and Ch/GA/SA membranes were of the same order of magnitude for acidic and neutral swelling media but they increased for alkaline solutions.

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“…The swelling rates of the Ch, Ch/GA and Ch/GA/SA hydrogel membranes were described with Schott , s second-order swelling kinetics [48]:…”

Section: Case III (Or Anomalous Diffusion Non-fickian Diffusion)mentioning

confidence: 99%

pH-responsive hydrogel membranes based on modified chitosan: water transport and kinetics of swelling

2015

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“…Water uptake was plotted against square root of time (t 1/2 ) to explore the mechanism of drug release [15] and the plots are shown in Figure 3a-c. For polymers with a long swelling time, Schott [16] proposed Eq 3:…”

Section: Effect Of Temperature On Water Uptake Of Grewia Gummentioning

confidence: 99%

Grewia Gum 1: Some Mechanical and Swelling Properties of Compact and Film

Nep

Conway

2011

Trop. J. Pharm Res

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“…The swelling kinetics were studied using Fickian and Schott models, respectively (Schott 1992). A pre-condition for the application of Fickian law is that the diffusion coefficient does not remain constant.…”

Section: Swelling Behaviors Of the Hydrogelsmentioning

confidence: 99%

Synthesis and Characterization of Alkali Lignin-based Hydrogels from Ionic Liquids

Chen

Yang

et al. 2017

BioResources

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Hydrogels from alkali lignin were prepared and shown to display unique swelling. Variable lignin contents (6.25%, 10.00%, 12.50%, and 14.29%) were successfully grafted with both N,N'-methylenebisacrylamide (MBA) and acrylamide (AM). Ionic liquids such as 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) were used to avoid harsh, unfriendly solvents. All materials were characterized using X-ray diffraction (XRD) FT-IR spectroscopy, scanning electron microscope (SEM), thermogravimetric analysis (TGA), and swellability. The swelling behaviors of the hydrogels were noticeably influenced by their lignin content. The degree of equilibrium swelling (the maximum swelling degree) decreased with increasing content of lignin. The highest swelling degree (1,650%) was obtained at 6.25 wt% lignin. Kinetics revealed that the swelling behaviors of hydrogels were well-fitted by the Schott model.

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Swelling kinetics of polymers

Cited by 440 publications

References 9 publications

pH-responsive hydrogel membranes based on modified chitosan: water transport and kinetics of swelling

pH-responsive hydrogel membranes based on modified chitosan: water transport and kinetics of swelling

Grewia Gum 1: Some Mechanical and Swelling Properties of Compact and Film

Synthesis and Characterization of Alkali Lignin-based Hydrogels from Ionic Liquids

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