Hydrogels relative viscosity

A major challenge in the development of these two sensors was the selection of the proper electrolyte. For the Back Cell design, the polymer electrolyte required a unique set of properties. The polymer must have relatively high viscosity upon fabrication to prevent it from entering the pores of the substrate and blocking the triple points. The polymer must have sufficient ionic conductivity to eliminate pick-up of electrical noise. In addition, the polymer must have a stable water content at the high relative humidities found in respirator circuits. An obvious requirement is that the gas must dissolve in the polymer electrolyte. For the CO2 sensor, an enzyme, carbonic anhydrase, is used to improve response time. Therefore, the hydrogel must provide an hospitable environment for the enzyme to retain its activity. 

The massive effect of this relatively small (about 0.7%) concentration of MAA on polymer properties (swelling, viscosity, etc.) indicates that monomer purity should be a driving concern in the synthesis of soluble hydrogel polymers, and that EWC measurements in unbuffered solution should be treated with caution. On the other hand, the incorporation of trace quantities of acidic and basic monomers into this type of polymer may prove a useful method of behavioral modification. 

Subsequent to the sol phase, the viscosity of the reaction mixture rises and a hydrogel of amorphous sodium aluminosilicate is formed. Precipitation is carried out in relatively dilute solution and the amorphous sodium aluminosilicate has typically a high water content [20,100,101,103,104,108-110,112,119,122,126,137]. 

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