Ethylene Coordinative Chain Transfer Polymerization‐Induced Self‐Assembly (CCTPISA)
Résumé
Block copolymers based on ethylene (E) and butadiene (B) were prepared using the ansa-bis(fluorenyl complex {Me2Si(C13H8)2Nd(BH4)2Li(THF)}2 in combination with (n-Bu)(n-Oct)Mg (BOMAG) as a chain transfer agent. The diblock copolymers incorporating a soft poly(ethylene-co-butadiene) segment, called EBR for Ethylene Butadiene Rubber, and a hard polyethylene (PE) one were obtained by simply adjusting the different feeds of monomers during the polymerization. The soluble EBR block was formed first by feeding the catalytic system dissolved in toluene at 70 °C with a mixture of ethylene and butadiene (E/B molar ratio = 80/20). Then the feeding was stopped leading to the consumption of a large part of the residual monomers. The reactor was finally fed with ethylene to form the PE block. By varying the molar mass of the latter, it is shown that the resulting soft-b-hard block copolymers can self-assemble simultaneously to the growth of the PE block in agreement with a polymerization-induced self-assembly (PISA) mechanism. The selfassembly is discussed considering the reaction conditions, the crystallization of the PE block and the polymerization mechanism involved.
Domaines
Polymères
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