Control of Slow Release and Diffusion Processes

Another type of reaction control realized by isotonic contraction of a PMAA membrane is shown in Fig. 27 In this case the invertase solution was placed in a glass tube, the lower part of which was loosely wrapped with the PMAA membrane. The contraction of the membrane, bringing about the shrinkage of the pore radius (isotonic contraction cf. Fig. 20 a) interferes with the permeation of the substrate molecules from outside. Fig. 27 shows the effects of pH change and addition of PEG on the rate of hydrolysis. It is seen that the addition of a small amount of PEG impedes the hydrolysis completely, whereas a pH change has no effect on the rate. PEG molecules adsorbed on the PMAA membrane can be removed by rinsing with a dilute NaOH 

4 Chemomechanical Systems Based on Electrokinetic Processes (Electro-Activated Chemomechanical Systems) 

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