New technologies constantly generate new demands for exotic materials to be used in severe environments. The rapid developments of aerospace industries during the last two decades have required new materials to survive extreme high and low temperatures and various radiations. The exploration of new energy sources, e.g., solar and geothermal, has led us to develop new solar collectors and geothermal devices. Even the search for new oils has demanded that we study the corrosive environment of oil fields. In the telecommunication industries, optical fibers have been adopted broadly to replace metallic conductors. However, none of the optical fibers can survive abrasion or corrosion without the application of a coating material. For microelectronics, protection in terms of coatings and encapsulants is deemed necessary to prevent corrosion. One of the major causes of corrosion has been shown to be water which appears to be abundant in our earthly environments. Water can attack the bulk adhesive (or sealant), the interface, or the adherend. Water can also cause delamination of coating film, and it is definitely the major ingredient in causing cathodic or anodic corrosion. Thus, water becomes the major obstacle in solving durability problems of various materials in harsh environments.