Fluorocarbon polymers etching treatments

The treatment for fluorocarbon polymers is usually based upon metallic sodium dissolved in a solution of naphthalene in a polar aprotic solvent such as tetrahydrofuran, although other etch treatments such as a solution of alkali metal in liquid ammonia [12] have been reported [13]. Details for the preparation of the treatment solutions have been published [14] and solutions of sodium naphthalenide are commercially available, e.g. under the trade name Tetraetch from W. L. Gore Associates Inc. These commercial pretreatments are relatively easy and safe to operate and widely used in industry. Also, it is possible to purchase fluorocarbon polymers already treated by such chemical processes. 

Liquid etchants can be used for chenucal modification or dissolving surface contamination. Etchants effectively treat irregularly shaped objects that are difficult to treat by other adhesion-promoting processes such as corona or flame treatment. A number of etching solutions and procedures have been developed for specific polymeric surfaces. The choice of the liquid etchant depends on the polymers. Polyolefins are usually treated by oxidizing acids such as chromic, sulfuric, nitric, or mixtures of these. Fluorocarbons are usually treated by sodium-napthalene etching solution. 

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