Laser Stimulated Shape Memory Polymer with Inclusion of Gold Nanorod-Effect of Aspect Ratio and Critical Role of On-resonance Irradiation

Gold nanorods (AuNRs) are excellent photothermal agents to enable a variety of laser stimulated functional polymers. One key issue is to maximize the photothermal conversion efficiency of AuNRs. In this study, the light responsive AuNR/shape memory polymer (SMP) nanocomposites with inclusion of AuNRs of varied aspect ratios were prepared, characterized, and their laser irradiation induced bending behavior was investigated. The critical role of the on-resonance irradiation condition-a close match of the longitudinal plasmon resonance of the AuNR with the wavelength of the incident laser-has been established. It allows for maximizing the photothermal conversion efficiency of AuNRs to result in the rapid and large deformation of the AuNR/SMP nanocomposites. For the AuNR/SMP nanocomposite films prepared under similar processing conditions, the close-to-resonance irradiation at a 1.27 W/cm2 was able to induce a bending rate of 27°/s and maximum bending angle of 90.4°. In contrast, the off-resonance irradiation at a 1.89 W/cm2 resulted in negligible response.