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Abstract

A method of analyzing molecular layers of amino-functional group coupling agents on inorganic substrates is disclosed. A saturated solution of 1-dimethylaminonaphthalene-5-sulfonyl chloride is added to a sample to be tested, and sufficient time is allowed, with or without heating, for the reaction of the 1-dimethylaminonaphthalene-5-sulfonyl chloride with any amino functional group coupling agent which might be present. The color intensity of the reaction product is compared under ultraviolet light in an otherwise substantially dark room with the color intensity of standards representative of known thicknesses of coupling agent to determine the existence and thickness of the coupling agent on the particles being analyzed. If the reaction is allowed to progress without heating, rinsing will wash away some of the coating that is not sufficiently chemically bound to the substrate, and thus will decrease the amount of reaction product - of which the coating is a substituent - that can be observed on the substrate. The reduced reaction product is manifested by a reduced color intensity of the sample when viewed under ultraviolet light in a dark room. The occurrence of this reduced color intensity, relative to a part of the same sample reacted with heating, indicates insufficient chemical bonding of the coating to the substrate.

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First Claim