Effects of Network Inhomogeneity in Poly(<i>N</i>-isopropylacrylamide) Gel on its Surface Structure

Suzuki, Atsushi; Kobiki, Y.; Yamazaki, M.

doi:10.1143/jjap.42.2810

Cited by 7 publications

(6 citation statements)

References 3 publications

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“…All images (256 samples/line 256 lines) were processed by first order flattening in order to remove the background slope and the contrast and brightness were adjusted. [14][15][16][17]. Figure 1 shows the changes in the swelling ratio of as-prepared poly(sodium acrylate) gel synthesized with 4wt% Al(OH) 3 at room temperature when the solvent (100ml of pH-controlled water or NaCl aqueous solution) was repeatedly exchanged every 24 hours.…”

Section: Measurementsmentioning

confidence: 99%

“…Microdomains, which were strongly affected not only by the amount of Al(OH) 3 but also by the thickness of the gels, were observed. In order to identify the images quantitatively, the autocorrelation function, g(r), was calculated using the height values obtained from the AFM images [16,17]. The data points were found to fit well to a Gaussian distribution, which is scaled by a decay function, g(r)/R rms 2 -g 0 =exp[-(r /ξ) 2 ].…”

Section: Afm Observations Of Surface Microstructures Of Dehydrated Gelsmentioning

confidence: 99%

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Synthesis, swelling behavior and surface microstructure of poly(sodium acrylate) gels cross-linked by aluminum ions

Harada

Hirashima

Suzuki

et al. 2005

European Polymer Journal

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We report the synthesis and some unique properties of polymer gels cross-linked by metal ions. They are made of poly(sodium acrylate) and aluminum ions. Cylindrical and thin plate gels were synthesized in glass molds by mixing poly(sodium acrylate) with aluminum hydroxide of various concentrations. The swelling ratio of the gels was measured by changing the solvent pH and adding NaCl with different concentrations. Each gel was found to swell at the first stage and shrink thereafter by repeated solvent exchanges; the swelling ratio ultimately returned to the initial one just after gelation. These features could be explained using a qualitative model based on the ion exchange and the formation of hydrogen bonding. A characteristic surface microstructure was observed on the dehydrated gels using an atomic force microscope. The microstructures were analyzed in terms of the autocorrelation function and the root-mean-square roughness. The surface microstructure of this system was characterized by the microdomains, the shape of which was found to depend strongly on the amount of aluminum ions and the gel thickness at gelation. It could be controlled not only by the concentration of the cross-linker but also by the dehydration condition.

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Section: Measurementsmentioning

confidence: 99%

Section: Afm Observations Of Surface Microstructures Of Dehydrated Gelsmentioning

confidence: 99%

Synthesis, swelling behavior and surface microstructure of poly(sodium acrylate) gels cross-linked by aluminum ions

Harada

Hirashima

Suzuki

et al. 2005

European Polymer Journal

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“…The second process was the polymerization of AAm in the presence of the NIPA gel particles and the crosslinker BIS to obtain the hybrid gels. In this process, the hybrid gels were synthesized in two shapes, thin cylinder2 and thin plate 3. The gels for the measurements of the swelling curves were thin cylindrical gels prepared in a glass microcapillary with an inner diameter of 633 μm.…”

Section: Methodsmentioning

confidence: 99%

“…Some unique functions of polymer gels could be explained by investigating the network structures in some specific size. As for the swelling behavior, it has been pointed out2, 3 that not only the interactions with monomers but also the domains in submicrometer scale have an important role in explaining the macroscopic volume and the phase transition. The crosslinking process at gelation itself produces inhomogeneity due to the fluctuation of the pregel solution,4, 5 since the fluctuations should be frozen into the gel structure in the gelation process.…”

Section: Introductionmentioning

confidence: 99%

Effects of guest microparticles on the swelling behavior of polyacrylamide gels

Suzuki

Okabe

Suzuki

2005

J Polym Sci B Polym Phys

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We report the effects of guest particles on the swelling properties of bulk polyacrylamide gels. The guest particles were the spheres of poly(N‐isopropylacrylamide) gel with submicrometer diameter, which were synthesized by an emulsion‐polymerized reaction in water. Polyacrylamide gels were prepared by a free radical polymerization reaction, immobilizing the gel microparticles with different concentrations at gelation. The macroscopic swelling ratio of this hybrid gel in a cylindrical shape was measured as functions of temperature and acetone concentration. The presence of guest particles was found to strongly affect the swelling behavior in the bulk gels when the concentration of incorporated particles exceeded a threshold. The experimental results indicated that the macroscopic volume in response to the temperature change should be determined by the guest particles above the threshold. On the other hand, the hybrid gel could not evidently shrink by adding acetone when the concentration of guest particles exceeded the threshold. To make clear the distribution of guest particles in the bulk networks, the fractured surfaces of dried gels were imaged by tapping mode atomic force microscopy. The guest particles were found to aggregate in the bulk homogeneous networks to form microdomains with densely connected structure, which became larger with increasing particle concentration. The roles of bulk networks as well as guest particles on the swelling behavior of hybrid gels were qualitatively discussed on the basis of the incorporated structure of guest particles, depending on the concentration of guest particles. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1696–1704, 2005

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“…An influence of the solvent employed in preparation on the properties of hydrogels has been studied before. For example, Suzuki et al report that pNIPAm films were rather rough when produced in water at temperatures above the LCST, which they explain with fast precipitation [29]. Sayil and Okay measured the swelling ratio of pNIPAm hydrogels [30] and found the swelling ratio to be correlated with the temperature at the time of preparation.…”

Section: Introductionmentioning

confidence: 99%

Electrochemically produced responsive hydrogel films: Influence of added salt on thickness and morphology

Bünsow

Johannsmann

2008

Journal of Colloid and Interface Science

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Effects of Network Inhomogeneity in Poly(N-isopropylacrylamide) Gel on its Surface Structure

Cited by 7 publications

References 3 publications

Synthesis, swelling behavior and surface microstructure of poly(sodium acrylate) gels cross-linked by aluminum ions

Synthesis, swelling behavior and surface microstructure of poly(sodium acrylate) gels cross-linked by aluminum ions

Effects of guest microparticles on the swelling behavior of polyacrylamide gels

Electrochemically produced responsive hydrogel films: Influence of added salt on thickness and morphology

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