Cross-linking polymerization, rate, determining

An important quantity that can be deduced from the reaction profile is the rate of the cross-linking polymerization (Rp), i.e., the number of double bonds polymerized or of cross-links formed per second. Rp values were determined from the maximum slope of the kinetic curves (usually reached for conversion degrees between 20 and 40%). Table I summarizes the Rp values for the two photoresists tested under various conditions, namely conventional UV and continuous or pulsed laser irradiation at different light intensities. According to these kinetic data, Rp increases almost as fast as the light-intensity the ratio Io/Rp which is directly related to the product of the light-intensity and the required exposure time was found to vary only in the range 10-8 to... 

Extensive research on sol—gel processing of silicic acid esters, eg, tetraethoxysilane (TEOS), Si(OC2H5)4, in alcohol—water mixtures has ducidated silica polymerization in nonaqueous solvents (54,55). The relative rates of hydrolysis and condensation depend on the substrate, water, and catalyst (acid or base) concentrations these rates determine the polymer structure. For example, acid-catalyzed hydrolysis of TEOS at low water concentrations produces linear polymers. These solutions yield fibers upon spinning. Conversely, high H20 /TEOS ratios favor the formation of highly cross-linked polymers under... 

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