Noncatalytic surfaces

The reaction proceeds until aU. available monomer has reacted or until it is terminated by an acidic species. The gel point in these m situ polymerizations, as represented by the time of fixture, occurs within several seconds on strongly catalytic surfaces such as thermoset mbbers to several minutes on noncatalytic surfaces. 

A useful, semiempirical approach to noncatalytic surface reactions is to postulate a rate equation of the form... 

In this chapter we discuss the electrochemical model of electroless deposition (Sections 8.2 and 8.3), kinetics and mechanism of partial reactions (Sections 8.4 and 8.5), activation of noncatalytic surfaces (Section 8.6), kinetics of electroless deposition (Section 8.7), the mechanism of electroless crystallization (Section 8.8), and unique properties of some deposits (Section 8.9). 

Noncatalytic surfaces (e.g., nonconductors, noncatalytic metals, noncatalytic semiconductors) have to be activated (i.e., made catalytic) prior to electroless deposition. This activation is performed by generating catalytic nuclei on the surface of a noncatalytic material. Two major types of processes have been used to produce catalytic nuclei electrochemical and photochemical. 

Electrochemical Activation. In the electrochemical method, catalytic nuclei of metal M on a noncatalytic surface S may be generated in an electrochemical oxidation-reduction reaction,... 

This paper will put together facts and ideas in Alfin polymerization which are related to the surface effects. The specific components of the reagent, their proportions, and their probable arrangement will be described. Polymerization will be interpreted as a phenomenon which occurs only on the surface and actually only on certain areas of that surface. Once started, chain growth does not spread to other areas or into solution, but remains on that particular area. In line with other catalysts, the Alfin reagent can be spread upon certain noncatalytic surfaces and can be poisoned by various salts or ions. The special features are further exemplified by the fact that the action is specific for extremely few monomers. Finally, a manner by which polymerization actually occurs on such a surface will be suggested. 

The electroless deposition involves the chemical reductirMi of a metal salt from the solution to a surface. Noncatalytic surfaces, such as insirlating polymers, have to be activated (made catalytic) prior to the electroless deposition. Usually, this is performed by generating metal nuclei on the surface of the noncatalytic material. In this way, the metal ion is preferentially reduced at the sensitized surface so that only this surface is plated with the desired metal. ... 

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