A brief introduction to polymers and concepts of polymer modification of bentonite for barrier applications

Polymer-modified bentonite has reached significant attention in recent years, as polymers have been found to increase the resistance of clay barriers to detrimental environmental conditions. Studies on polymer modification of clays for barriers, in most cases, address a specific bentonite with a specific means of modification based on a specific polymer product. The term polymer, however, generally describes a broad category of macromolecules able to create a wide range of possible properties of the modified clay. This article reviews the basics of polymer modification of clays for use in hydraulic barriers to provide a general basis for comparison and design of different modification products and methods. Basics of both primary material categories, that is, polymer and clay, are presented, followed by possible polymer–clay interactions related to polymer charge properties and structure. Possible enhancements associated with polymer modification, but also open questions are addressed.