Breaking translational symmetry in polymer crystallization

While one of the fundamental laws in crystallization is translational symmetry, it is often broken in a class of polymer crystals defined as shape-symmetry incommensurate crystals (SSICs) which include helical, helicoidal, scrolled, tubular crystals, and the newly discovered crystalsomes. The reason for the broken translation symmetry in SSICs can vary, and in this talk, we discuss the chain architecture effect on polymer crystallization. While classical flat single crystals are obtained in linear polymers, non-flat spherical or tubular crystals were observed in molecular bottlebrush polymers and end-functionalized polymers. The spherical and tubular morphologies suggest the spontaneous translational symmetry breaking during crystal growth, which is attributed to lamellar imbalance associated with chain architectures. Crystallization kinetics in this class of polymers will also be discussed.