Organocatalyzed Polymerization of PET- mb -poly(oxyhexane) Copolymers and Their Self-Assembly into Double CrystallineSuperstructures

Double crystalline multiblock copolymers exhibit two well-defined melting temperatures associated with the two phases formed by their constituent blocks. The crystalline superstructure formed in these copolymers is complex and depends on the miscibility of both comonomers. In this work, an innovative series of double crystalline poly(ethylene terephthalate)-mb-poly(oxyhexane) multiblock copolymers were prepared in one pot. Previously synthesized low molecular weight poly(oxyhexane)telechelic diol and poly(ethylene terephthalate) (PET) oligomers were reacted by transesterification using an organic catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene/benzoic acid), in a solvent-free process. The copolymerization was demonstrated by 1H NMR and 13C NMR spectroscopies, and the random distribution of poly(oxyhexane) chains was confirmed. We found that all compositions exhibited double crystallinity, but the crystallization of the copolymers was strongly affected by the PET/poly(oxyhexane) composition. When the PET cont...