Polymorphic Behavior and Phase Transition of Poly(1-Butene) and Its Copolymers

The properties of semicrystalline polymeric materials depend remarkably on their structures, especially for those exhibiting a polymorphic behavior. This offers an efficient way to tailor their properties through crystal engineering. For control of the crystal structure, and therefore the physical and mechanical properties, a full understanding of the polymorph selection of polymers under varied conditions is essential. This has stimulated a mass of research work on the polymorphic crystallization and related phase transformation. Considering that the isotactic poly(1-butene) (iPBu) exhibits pronounced polymorphs and complicated transition between different phases, the study on its crystallization and phase transformation has attracted considerable attention during the past decades. This review provides the context of the recent progresses made on the crystallization and phase transition behavior of iPBu. We first review the crystal structures of known crystal forms and then their formation conditions and influencing factors. In addition, the inevitable form II to form I spontaneous transition mechanism and the transformation kinetics is reviewed based on the existing research works, aiming for it to be useful for its processing in different phases and the further technical development of new methods for accelerating or even bypass its form II to form I transformation.