Abstract
Most of the polymeric materials one encounters so widely are heterogeneous. For instance, commercial plastics may be blends of immiscible polymers; they may contain antioxidants or other modifiers which are not totally soluble; andfrequently they have added inorganic fillers. Other examples of inhomogeneity in polymer systems are composites, partially crystalline materials, surface layers, ionomers, and block and graft copolymers. In some cases the heterogeneity is the essence of the material's virtue (e.g., its mechanical properties). In other cases heterogeneity is an affliction. But, whether one's goal is to maximize or minimize the effect of nonuniformity, it is well to understand the factors which determine the features of inhomogeneous polymers. This we will attempt to do in a qualitative way by describing, from a simple molecular point of view, the entropy and energy terms which control the systems' physical features. Rather than dealing in generalities, however, let us focus on two particular cases : interfaces between immiscible polymers, and block copolymers. This should provide the reader with some insight into the myriad of recent developments in the field of polymer blends, composites, and microheterogeneities.
Engineering Plastics-Recent Developments in Synthesis and Applications. Synthesis and Properties of Polyester-Polyamide Block Copolymers.