Synthesis and thermal characterization of some novel ABA block copolymers

The synthesis of some novel ABA block copolymers is reported. The block A is a PPO while theblock B is a random copoly(aryl ether sulfone), synthesized with three different molecularweights. The block copolymers were obtained by a two step procedure consisting on thefunctionalization of the random copoly(aryl ether sulfone) followed by a condensation withPPO. Spectroscopic techniques (1H NMR and 13C NMR) were used to characterize the polymersobtained from each step. The NMR data proved the complete conversion of amino groups afterthe first reaction step and gave some useful insights on the completion of the second step.Copolymer formation is supported by a comparisonof the thermal behavior of the block copolymerswith respect to the physical blends of thetwo homopolymers. DSC and DMA analysesshowed double glass transitions for the physicalblends which could be related to the immiscibilityof the two homopolymers, while, in contrast,the block copolymer showed single glasstransition. Blends of ABA triblock copolymer/PPO and of ABA triblock/copoly (arylen ethersulfone)s were also prepared. These blends,tested by DSC, showed a good level of compatibilityof the ABA copolymer with its singularconstituents.