Simultaneous Physical Cross-Linking and Mechanical Strengthening of Elastomers by Enantiomeric Interactions through Reactive Processing AITranslate

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DOI：https://doi.org/10.1021/acsapm.3c01966

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Exploiting robust elastomers without sacrificing thermoplasticity has been extremely desired for decades, yet it is challenging. Noncovalent interactions are a versatile platform for the development of networks with reversible cross-linking joints. Herein, an alternative strategy is proposed to straightforwardly construct a mechanical strengthening elastomer with a dynamic cross-linking network via multiple H-bonding between enantiomeric polymer pairs. First, poly-l-lactic acid (PLLA)/poly-d-lactic acid (PDLA) were pregrafted onto polyolefin elastomer (POE) to obtain POE-g-PLLA and POE-g-PDLA, respectively. Due to the specific intermolecular interactions, stereocomplex crystals (SC) were formed and preserved during the subsequent melt-compounding. SC enabled the immobilization of the cross-linking point within the POE matrix, facilitating the construction of the SC noncovalent network (SC-N). As such, SC-N endowed the elastomer with synergistically enhanced modulus, strength, and heat resistance, as compared with traditional chemical cross-linked counterparts. More importantly, SC-N displayed desirable reprocessability upon the temporary dissociation of physical cross-linking linkages above Tm,SC. These findings may open a feasible avenue of designing advanced elastomers with dynamic behaviors and provide deeper insights into the underlying mechanism of covalent adaptable cross-linking.