Effect of the crosslinking level on the properties of temperature‐sensitive poly(<i>N</i>‐isopropylacrylamide) hydrogels

Zhang, Xian‐Zheng; Wu, Daqing; Chu, Chih‐Chang

doi:10.1002/polb.10388

Cited by 85 publications

(54 citation statements)

References 52 publications

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“…NIPAAm and MBAAm during the gelation process, the resulted PNIPAAm hydrogel would have almost the same chemical structure as pure PNIPAAm (without the presence of microgels). The hydrophilic/ hydrophobic balance would remain almost the same, thus the LCST did not change significantly, which also agrees with our previous findings [29].…”

Section: Lcst Behaviorsupporting

confidence: 92%

Fabrication and characterization of microgel-impregnated, thermosensitive PNIPAAm hydrogels

Zhang

Chu

2005

Polymer

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Section: Lcst Behaviorsupporting

confidence: 92%

Fabrication and characterization of microgel-impregnated, thermosensitive PNIPAAm hydrogels

Zhang

Chu

2005

Polymer

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“…Swelling of the polymer membrane continues until the forces due to swelling of the polymer balance the osmotic pressure, driving the solvent into the swollen polymer. The swelling process of hydrogels is a complicated phenomenon and involves three successive steps: (i) the diffusion of water molecules into the polymer network, (ii) the relaxation of hydrated polymer chains and (iii) the expansion of the polymer network into the surrounding aqueous solution [21]. Figures 6 and 7 present the dynamic swelling data for non-cross-linked chitosan membrane and crosslinked chitosan membranes in buffered aqueous solutions of constant ionic strength (0.145 M at 37°C).…”

Section: Swelling Kinetics Of Hydrogel Membranesmentioning

confidence: 99%

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

2015

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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 of CS hydrogels is a complex process which can be divided into several stages: diffusion of water molecules into the polymer network followed with the relaxation of hydrated chains and the expansion of the polymer network in the aqueous media [44]. The swelling behavior depends on the media pH and ionization of the polymer's functional groups, network structure, degree of crosslinking, and the nature of crosslinking agent [45].…”

Section: Swelling Index and Mucoadhesion Studiesmentioning

confidence: 99%

The Effect of β-Glycerophosphate Crosslinking on Chitosan Cytotoxicity and Properties of Hydrogels for Vaginal Application

et al. 2015

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Mucoadhesive gelling systems based on chitosan and chitosan/β-glycerophosphate (β-GP) were developed in order to increase clotrimazole residence time in the vaginal cavity. Ex vivo mucoadhesiveness using porcine vaginal mucosa followed with mechanical, viscoelastic, and swelling properties of prepared hydrogels were evaluated. Drug-free, sterile, unmodified, and β-GP crosslinked chitosan were investigated for the in vitro cytotoxicity in CRL 2616 human vaginal mucosa cells using MTT assay, fluorescent microscopy, and flow cytometry analysis. Chitosan/β-GP hydrogels exhibited pseudoplastic and thixotropic properties. Ionic interaction between β-GP and chitosan improved mechanical properties of hydrogels in terms of hardness, cohesiveness, and compressibility. The hydrogels' ability to interact with porcine vaginal mucosa (measured as force of detachment and work of adhesion) was comparable to those obtained with reference mucoadhesive gel Replens™. Surprisingly, greater mucoadhesive properties were noticed for chitosan/β-GP hydrogels. The cytotoxic effect of unmodified and β-GP crosslinked chitosan was hardly affected by chitosan molecular weight, exhibited mainly through inducing apoptosis, and was found to be significantly lower in the presence of chitosan/β-GP. Furthermore, the higher amount of β-GP was used to crosslink chitosan, the lower cytotoxic effect was observed.

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Effect of the crosslinking level on the properties of temperature‐sensitive poly(N‐isopropylacrylamide) hydrogels

Cited by 85 publications

References 52 publications

Fabrication and characterization of microgel-impregnated, thermosensitive PNIPAAm hydrogels

Fabrication and characterization of microgel-impregnated, thermosensitive PNIPAAm hydrogels

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

The Effect of β-Glycerophosphate Crosslinking on Chitosan Cytotoxicity and Properties of Hydrogels for Vaginal Application

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