Belgrade : Materials Research Society of Serbia – MRS-Serbia
Abstract
In recent years, photoactuators as a class of smart materials that can produce a reversible mechanical deformation under light stimuli have attracted tremendous interest due to their potential applications in soft robotics, artificial muscles, and smart devices. Currently, the fabrication of photoactuators is mainly based on photothermal actuation mechanisms which include expansion/contraction, molecule sorption/desorption, and phase transition. Thermosensitive hydrogels with gold nanoparticles (AuNPs) are probably the most commonly used active layers that absorb light energy and convert it to thermal energy, causing reversible mechanical deformation such as bending, curling, and spiraling. This work describes hydrogel nanocomposite photoactuators based on AuNPs and thermosensitive poly(N-isopropylacrylamide) (Au-PNiPAAm), obtained by gamma irradiation. The different shapes of AuNPs were incorporated into PNiPAAm hydrogel, nanospheres with radius 5-10 nm and nanorods with aspect ratio 5 (radius 10 nm, length 50 nm). Swelling and deswelling kinetics of Au-PNiPAAm hydrogel nanocomposite photoactuators were investigated in water at 25C and 48C, respectively. All samples showed non-Fickian diffusion (both diffusion and polymer chains relaxation processes control the fluid transport) indicating that incorporation of different shapes of AuNPs into matrices has no influence on the diffusion model. On the other hand, the volume phase transition temperature (VPTT) of photoactuators can be adjusted by the incorporation of different shapes of AuNPs. It has been observed that VPTT decreases from 32.5C for Au nanorods to 30.5C for Au nanospheres, causing a more pronounced photothermal effect in the case of nanospheres.Twenty-second Annual Conference YUCOMAT : August 30 - September 3, Herceg Novi, 202
