(196l) Synthesis of Thermoplastic Polydimethylsiloxane with L-Phenylalanine-Based Hydrogen-Bond Network and its Self-Healing Property

Polydimethylsiloxane (PDMS) with L-phenylalanine was found to possess thermoplastic property and self-healing property due to the crosslinkings through hydrogen bonding. The PDMS with L-phenylalanine was synthesized in two steps. The amino-acid terminated PDMS was first synthesized by adding L-phenylalanine to the end of amino-propyl terminated PDMS, followed by the condensation polymerization of the amino-acid terminated PDMS. In order to investigate the mechanical and the self-healing properties of PDMS with L-phenylalanine, the tensile testing and the dynamic mechanical analysis (DMA) were conducted. It was found by the tensile testing that the Young’s modulus of the synthesized PDMS increased as the amount of L-phenylalanine increased. Especially, the Young’s modulus of the thermoplastic PDMS containing L-phenylalanine was at most about 4 times higher than that of the thermoplastic PDMS without L-phenylalanine. From the DMA analyses, it was found that the synthesized PDMS with L-phenylalanine presented a relatively high storage modulus (~100 kPa) at around room temperature, which gradually decreased down to ~20 kPa at higher temperature of 150°C. The melting temperature of thermoplastic PDMS with L-phenylalanine was also confirmed to be ~120°C. Moreover, in order to investigate the self-healing property, the tensile testing was conducted with the self-healed sample as well as the original sample. The self-healed sample was prepared by cutting it into two pieces and by contacting the pieces at room temperature and leaving them for 24 h for the self-healing. Considering the Young’s moduli of the self-healed sample and the original sample, the PDMS was found to possess the self-healing property.. The Young’s modulus of the self-healed PDMS could maintain at least 70% of the Young’s modulus of the original sample. In detail, the Young’s modulus of the self-healed samples of PDMS without L-phenylalanine and that of the PDMS with L-phenylalanine were found to be 139 kPa and 856 kPa, respectively, while the Young’s moduli of the original samples of PDMS without L-phenylalanine and the PDMS containing L-phenylalanine were 190 kPa and 790 kPa, respectively. (n=3)