Ammonia → Purpurogallin

Participants

Reaction Steps

TiO2 grind [16.4 g Ti Pure® titanium dioxide supplied by DuPont Company, Wilmington, Del., 0.7 g dispersing, 0.1 g ammonia (28% strength), 0.2 g surfactant, 0.1 g defoamer, and 1.6 g water] mixed with 54 g of the oxidative polymer and 8 grams of Butyl Cellosolve cosolvent, 1.5 grams of propylene glycol was added to 12.6 grams of water to form a paint. To the paint, 0.6 ml of P-6140 horseradish peroxidase P-6140 (EC 1.11.1.7) supplied by Sigma Chemical, PO Box 14508, St. Louis, Mo. 63178 (1 ml contains 21 mg enzyme which has an activity of 250 units/mg. One unit will form 1 mg of purpurogallin from pyrogallol in 20 sec. at pH 6 and 20 C.) was added (0.15 ml is equivalent to 3.15 mg enzyme having 250 units activity per mg). The pot mix was then conventionally applied to a plastic sheet as a clear layer having a dry film thickness of 50 microns. The layer was air dried for 4 days to form a film. Thereafter, specimens of the film were removed and measured for the degree of crosslinking achieved by the oxidizing enzyme. The film was found to have a swell ratio of 5.7 indicating significant crosslinking of the oxidative polymer by the oxidizing enzyme.

Provenance & Evidence