Multiblock copolymers poly(l-lactic acid)-block-poly(butylene succinate-co-butylene adipate)s (abbr. P(LLA-mb-BSA)s) are synthesized via a polycondensation/chain extension/coupling method using binary chain extenders. A poly(l-lactic acid) (PLLA) prepolymer synthesized via direct melt polycondensation of l-lactic acid is rapidly chain extended with a bis (2-oxazoline) to form hydroxyl terminated dimer, and the dimer is then chain extended/coupled with a hydroxyl terminated poly(butylene succinate-co-butylene adipate) (PBSA) prepolymer by a diisocyanate. The microstructure is characterized with GPC, 1H NMR and FTIR, and the thermo-mechanical properties are investigated with DSC, TGA, DMA, tensile, and impact testing. In the copolymers, the PLLA hard segments are crystallizable and the PBSA soft segments are amorphous, and only melting of PLLA segment was detected. Two independent glass transitions corresponding to both segments are observed, suggesting incompatibility between the two kinds of segments. The tensile modulus and strength decrease while the elongation at break and impact strength increase with increasing the weight percentage of PBSA segment (ϕw,PBSA). The mechanical properties can be tuned in wide range by ϕw,PBSA, from toughened thermoplastics with excellent tensile modulus, strength and impact strength to thermoplastic elastomers with high elongation at break.

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Polyolefin thermoplastic elastomers (TPE‐Os) are high‐performance polyolefins consisting of both plastic and rubber phases. Compared with other thermoplastic elastomers, the TPE‐Os possess better chemical stability, transparency, re‐processability, and electrical insulation, which renders their broad applications possible. By manipulating chain structures and topologies of the TPE‐Os, differently structured polyolefins with improved thermal and mechanical properties have been developed, including ethylene and α‐olefin random copolymers (POEs), olefin block copolymers (OBCs), comb‐shaped polyolefin elastomers (CPOEs), and dynamically cross‐linked polyolefin elastomers. Herein, we review the synthesis of the POE, OBC, CPOE, and dynamical cross‐linked polyolefin elastomer, including the catalyst systems, polymerization techniques, processes, and kinetic modelling. The characterization of the TPE‐Os and the relationships between the TPE‐O chain structure, aggregated state, and product performance are discussed. The future development of higher‐performance TPE‐Os is envisaged.