Synthesis and Characterization of Ring-Shaped Polystyrenes

Macrocyclic polystyrenes were prepared by coupling a two-ended living precursor dianions with 1,3-bis(1-phenylethylenyl)benzene (DDPE). Experiments were performed in a drybox apparatus, and macrocycles were obtained with a yield ranged between 40 and 55%. Simultaneously, besides the expected cyclic polymer, polycondensates (linear and cyclic) were formed. Thus, macrocyclic products were separated from the residual linear precursor and linear polycondensates byproducts by preparative high performance liquid chromatography at the exclusion−adsorption transition point. Isolation of highly pure cyclic polystyrenes (of different sizes) was carried out. Information on the chemical structure of the linear and cyclic polystyrenes were obtained by matrix-assisted laser desorption/ionization time-of-flight (MALDI−TOF) mass spectrometry, showing a good agreement with the expected structures. In addition, viscometry measurements by SEC (viscometry detector) showed that the ratio g‘ = [η]C/[η]L is equal to 0.67 in a good solvent and confirmed the high efficiency of the preparative liquid chromatographic separation.