The last twenty years or so have seen a flurry of activity in the synthesis of new polymer systems. This interest has developed largely as a result of the increased need for advanced materials. Despite the emergence of a number of outstanding polymers, it is the polyimides that have captured the imagination of scientists and engineers alike as materials that offer outstanding promise for the high technology applic- ations of the future. The reputation of the polyimide has been established on the bases of outstanding thermal stability, excellent mechanical properties and the ability to be...