Isoprene Chain Shuttling Polymerization Mediated by a Heterobimetallic System Comprising La and Sc Amidinate Complexes: A One-Pot Process to Advanced Thermoplastic Elastomers

This study introduces a one-pot approach for synthesizing regio-multiblock copolymers with two tunable T g values from single conjugated dienes. A convenient acid–base reaction was used to synthesize mononuclear rare-earth metal complexes R 1 C 6 H 4 C(N-2,6- i Pr 2 –C 6 H 3 ) 2 RE( o -CH 2 C 6 H 4 NMe 2 ) 2 (R 1 = −OMe, RE = Sc ( 1 ), La ( 2 ); R 1 = −H, RE = Sc ( 3 ), La ( 4 ); R 1 = −CF 3, RE = Sc ( 5 ), La ( 6 )) in high yields. By carefully tuning the ratios of catalytic precursors 1 and 2 in conjunction with AlEt 3 and [Ph 3 C][B(C 6 F 5 ) 4 ] (borate), we achieved precise control over the 1,4- and 3,4-regioselectivity in isoprene chain shuttling polymerization. This approach yielded materials with enhanced elongation at break (ε) compared to blends with similar 3,4-contents. Notably, the combination of catalytic precursors 5, 6, AlEt 3 and borate further enabled the synthesis of multiblock copolymers, which exhibit thermoplastic-elastomer properties. By varying the reaction solvents and utilizing catalytic precursor pairs ( 1, 2 )/( 3, 4 )/( 5, 6 ) in conjunction with borate and AlEt 3, all resulting copolymers exhibit dual- T g values. These results highlight the versatility and potential utility of the chain shuttling polymerization strategy for designing polymer structures and tailoring the physical properties of polymers.