Reversible swelling

Zenkl et al. [51] presented another approach to design saccharide-sensitive nanobeads. They prepared particles (0 380 nm) based on poly (/V- i sopropy I aery I am ide) cross-linked with phenylboronic acid moieties. In the presence of a saccharide (glucose or fructose) the particles reversibly swell due to the formation of negative charges. A FRET-indicator couple (fhiorescein/rhodamine) is used to monitor the... 

Thickness changes in a six-cycle water-soaking/ovendrying test for an acetylated aspen flakeboard are shown in Figure 4 ( ). Control boards swelled more than 70 percent in thickness during the six cycles, compared with less than I5 percent for a board made from acetylated flakes. Acetylation greatly reduced both irreversible and reversible swelling. 

Surface engineering of polymers by infusion. Supercritical-fluid contact can reversibly swell some polymer surfaces and films thus helping to enhance impregnation by monomers with subsequent polymerization to form nanocomposite anchored layers. - ... 

Kokufuta, Zhang and Tanaka developed a gel system that undergoes reversible swelling and collapsing changes in response to saccharides, sodium salt of dextran sulfate (DSS) and a-methyl-D-mannopyranoside (MP) [126]. The gel consists of a covalently cross-linked polymer network of W-isopropylacrylamide into which concanavalin A (ConA) is immobilized. As shown in Fig. 31, at a certain temperature the gel swells five times when DSS ions bind to ConA due to the excess ionic pressure created by DSS. The replacement of the DSS by non-ionic MP brings about collapse of the gel. The transition can be repeated with excellent reproducibility. 

Fig. 7A—C. Biochemo-mechanical function of NIPA gel with immobilized concanavalin A (A) Schematic illustration of saccharide-responsive, reversible swelling of a NIPA gel loaded with concanavalin A. Na DS"- is dextran sulfate sodium (DSS). (B) Temperature dependence for equilibrated volume of NIPA gel including the Con A-DSS complex (DSS-gel, O), MP (MP-gel, ), and free of both DSS and MP (A). The latter was prepared as a control sample as described in the text except for the use of an aqueous Con A solution instead of the Con A-DSS solution. Hysteresis was observed in the volume changes of the MP-gel and free-Con A gel on heating and cooling, indicating a discontinuous phase transition. The diameter of each gel in the collapsed state, determined at 50 °C, was d0 = 0.074 mm the volume of this gel is denoted Vp. The concentration of dry matter in the collapsed state was estimated from the preparation recipe to be 90 wt%. (C) Repeated swelling/shrinking control at 34.5 °C by alternate binding of DSS and MP to gel-entrapped Con A. (E. Kokufuta, Y.-Q. Zhang and T. Tanaka [78])...

We next indicate how cell wall and membrane properties influence the kinetics of reversible swelling or shrinking of plant cells. When the water potential outside a cell or group of cells is changed, water movement will be induced. A useful expression describing the time constant for the resulting volume change is... 

Silicones are resistant to water between 0°C and 100°C. Steam, at higher temperatures in prolonged attack, destroys the system. Normally, silicone rubbers are resistant to salt solution and to dilute solutions of acids and bases. However, they are not resistant to organic solvents. In this case a reversible swelling takes place. 

Reversible swelling of the parotid glands has been reported occasionally after the use of chlorhexidine mouthwashes this is probably due to mechanical obstruction of the parotid duct by over-rigorous rinsing (SEDA-11, 481) (29). 

Resin type Matrix Structure Functional group Ionic form WVC (keqm" ) pH range Thermal stability rc) Reversible swelling (%)... 

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