| 摘要 |
A selective membrane, suitable for the potentiometric determination of the activity of ions present in solution, for ion-exchange or for the separation of ions, comprises a substantially water-insoluble active material of a particle size within the range of 1 to 50 microns and suitable for pearl-type electrical conduction and development of chemical equilibria at the two surfaces of the membrane, dispersed in a silicone rubber in such an amount that the particles are sufficiently in contact with each other for pearl-type electrical conduction to occur. The membrane can be made by dispersing the particles in a rubber-forming siloxane, and curing the resulting dispersion, as by adding curing agents and catalysts and curing at ambient or elevated temperature, to obtain said membrane. The active material may be an inorganic precipitate, a metal chelate, an ion exchange resin or a molecular sieve. In examples, membranes are made by cold-curing a mixture of an active material, a dimethylpolysiloxane, dibutyltindilaurate and hexaethoxydisiloxane, between two plastic sheets, using respectively (1) AgI and (2) BaSO4 as the active materials. |
