Strong, Resilient, and Sustainable Aliphatic Polyester Thermoplastic Elastomers

Thermoplastic elastomers (TPEs) composed of ABA block polymers exhibit a wide variety of properties and are easily processable as they contain physical, rather than chemical, cross-links. Poly(gamma-methyl-epsilon-caprolactone) (P gamma MCL) is an amorphous polymer with a low entanglement molar mass (M-e = 2.9 kg mol(-1)), making it a suitable choice for tough elastomers. Incorporating P gamma MCL as the midblock with polylactide (PLA) end blocks (f(LA) = 0.17) results in TPEs with high stresses and elongations at break (sigma(B) = 24 +/- 2 MPa and epsilon(B) = 1029 +/- 20%, respectively) and low levels of hysteresis. The use of isotactic PLA as the end blocks f(LLA) = 0.17) increases the strength and toughness of the material (sigma(B) = 30 +/- 4 MPa, eB = 988 +/- 30%) due to its semicrystalline nature. This study aims to demonstrate how the outstanding, roperties in these sustainable materials are a result of the entanglements, glass transition temperature, segment-segment interaction parameter, and crystallinity, resulting in comparable properties to the commercially relevant styrene-based TPEs.