Thermoplastic polydimethylsiloxane with l-phenylalanine-based hydrogen-bond networks

Thermoplastic polydimethylsiloxane (PDMS) containing l-phenylalanine was synthesized by the liquid-phase synthesis method with an Fmoc-protected amino acid and by the condensation polymerization. In order to investigate the mechanical and the thermoplastic properties of the PDMS with l-phenylalanine, the tensile testing and the dynamic mechanical analysis (DMA) were conducted. From the results of the tensile testing, it was found that the stress at break of the PDMS with l-phenylalanine nearly became seven times higher than that of the PDMS without l-phenylalanine. The DMA results revealed that the PDMS could maintain its storage modulus for three heating cycles, while the melting temperature was also kept at ∼120 °C. Moreover, the mechanical property was analyzed through two remolding cycles, and it was found that the PDMS could almost maintain its mechanical property after the heat remolding. Finally, it was found that the PDMS also possessed some self-healing property, where the Young's modulus of the cut PDMS could maintain at least 70% of its original Young's modulus after contact and self-healing.