Bifunctional Carbanionic Synthesis of Fully Bio‐Based Triblock Structures Derived from β‐Farnesene and ll‐Dilactide: Thermoplastic Elastomers

Abstract

Current environmental challenges and the shrinking fossil‐fuel feedstock are important criteria for the next generation of polymer materials. In this context, we present a fully bio‐based material, which shows promise as thermoplastic elastomer (TPE). Due to the use of β‐farnesene and L‐lactide as monomers, bio‐based feedstocks, namely sugar cane and corn can be used. A bifunctional initiator for the carbanionic polymerization was employed, to permit an efficient synthesis of ABA‐type block structures. In addition, the “green” solvent MTBE (methyl tert‐butyl ether) was used. This afforded low dispersity (Đ = 1.07 to 1.10) and telechelic polyfarnesene macro­initiators. These were employed for lactide polymerization to obtain H‐shaped triblock copolymers. TEM and SAXS revealed clearly phase‐separated morphologies and tensile tests revealed elastic mechanical properties. The materials featured two glass transition temperatures, at ‐ 66 °C and 51 °C as well as gyroid or cylindrical morphologies, resulting in soft elastic materials at room temperature.

Using Redox‐Switchable Polymerization Catalysis to Synthesize a Chemically Recyclable Thermoplastic Elastomer

“…This polymer was interesting because it features end‐blocks that are expected to form stereocomplexes, a well‐known property displayed by mixtures of PLLA and PDLA [61] . Notably, the accessibility of L‐THF‐D is enabled using the unidirectional, redox‐switchable polymerization method employed as opposed to conventional bidirectional, telechelic techniques used to synthesize triblock copolymers containing PLLA end‐blocks [37–41,62–66] . All copolymers were isolated on a multi‐gram scale and were confirmed to be triblock copolymers as determined by 1 H NMR, SEC, and DOSY spectroscopy (See Figure S22–50).…”

Using Redox‐Switchable Polymerization Catalysis to Synthesize a Chemically Recyclable Thermoplastic Elastomer

“…This polymer was interesting because it features end‐blocks that are expected to form stereocomplexes, a well‐known property displayed by mixtures of PLLA and PDLA [61] . Notably, the accessibility of L‐THF‐D is enabled using the unidirectional, redox‐switchable polymerization method employed as opposed to conventional bidirectional, telechelic techniques used to synthesize triblock copolymers containing PLLA end‐blocks [37–41,62–66] . All copolymers were isolated on a multi‐gram scale and were confirmed to be triblock copolymers as determined by 1 H NMR, SEC, and DOSY spectroscopy (See Figure S22–50).…”

“…[61] Notably, the accessibility of L-THF-D is enabled using the unidirectional, redoxswitchable polymerization method employed as opposed to conventional bidirectional, telechelic techniques used to synthesize triblock copolymers containing PLLA endblocks. [37][38][39][40][41][62][63][64][65][66] All copolymers were isolated on a multigram scale and were confirmed to be triblock copolymers as determined by 1 H NMR, SEC, and DOSY spectroscopy (See Figure S22-50).…”

Fine-Tuning Gradient Copolymers with Diverse and Controlled Microstructure and Mechanical Properties via Monomer Sequence Distribution: An In Silico Study

“…BAB-type triblock copolymers are known to form thermoplastic elastomers (TPEs) with noteworthy phase separation behavior and two distinct T g . ,,, Here, we aimed to investigate the tensile properties of the TPE system featuring dual T g and an isotropic microphase separation morphology.…”