@conference{
author = "Nikolić, Nikolina and Radosavljević, Aleksandra and Spasojević, Jelena and Stamenović, Una and Tadić, Julijana and Vodnik, Vesna and Kačarević-Popović, Zorica",
year = "2022",
abstract = "Recently, one of the fastest growing areas in materials sciences is the development of polymer-based smart materials, which can autonomously change their physical and/or chemical properties under external stimuli. Among them, photoactuators as 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 are probably the most commonly used active layers. The functional gold nanoparticles exhibit unique photo-thermal properties as a result of a surface plasmon resonance (SPR) electron-phonon process and intrinsic inter-band transitions. Upon immobilization in thermoresponsive hydrogel, they induce local photo-thermal shrinking under visible light irradiation and thus enable external wireless remote control of hydrogel device and programmable photo-thermomechanical motions such as bending, curling, and spiralling. In this work, bi-layered photoactuators based on thermosensitive poly(N-isopropylacrylamide) (PNiPAAm) hydrogel with incorporated gold nanoparticles as an active layer, and poly(vinyl alcohol) hydrogel as a passive layer were produced. Crosslinking of polymer matrix was done by combination of freeze-thaw and radiolytic methods, while nanoparticles were synthesized using the seed-mediated approach. Two different shapes of nanoparticles were incorporated into PNiPAAm hydrogel, gold nanospheres (AuNPs) with radius around 10 nm and gold nanorods (AuNRs) with aspect ratio of 5 (radius of 10 nm, length of 50 nm). The formation of nanoparticles within the active layer was confirmed by appearance of characteristic SPR bands with maxima around 540 nm for AuNPs, and transversal oscillation at 530 nm and longitudinal oscillation around 760 nm for AuNRs. The XRD data for both AuNPs and AuNRs are consistent with the face-centered cubic (fcc) crystal structure of bulk metallic gold, while the FTIR spectra indicated the existence of physical interaction between nanoparticles and polymer matrix. The influence of different shapes of nanoparticles on physicochemical properties of bi-layered photoactuators was investigated in order to determine swelling and deswelling properties, as well as volume phase transition temperature (VPTT). Incorporation of AuNRs into active layer of photoactuators leads to an increase of both swelling capacity and VPTT. The results obtained from compression measurements shows that mechanical properties of investigated systems depend on shape and concentration of incorporated gold nanorods. Moreover, the photo-thermo-mechanical effect induced by the visible light irradiation was visualized by bending deformation as a consequence of the energy conversion in the active layer",
journal = "ICARST-2022 : Second International Conference on Applications of Radiation Science and Technology" : Book of abstracts",
title = "Bi-layered Au-(PNiPAAm/PVA) hydrogel nanocomposite photoactuators for direct optical to mechanical energy conversion",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12495"
}
