Synthesis and properties of molecularly uniform oligourethanes with chain-folding units in the center

The study of a series of molecularly uniform poly(N-alkylurethanes) with a systematically varied and tailored chain architecture has shown that the packing and superstructure can be controlled by the primary structure of the urethane chain and reversibly altered by the sample treatment, respectively. Depending on the conformation or the stereogeometry of the constitutive unit built in the middle of the otherwise symmetrical oligourethane, chain-extended and/or chain-folded crystallization of the urethane chain can occur. The packing order, i. e., adjacent recentry chain-folding or chain-extended crystallization, and the thermal properties of the oligourethanes are related to the chemical structure of the central constitutive unit.