Light- and Solvent-Responsive Bilayer Hydrogel Actuators with Reversible Bending Behaviors


LİMAN G., Mutluturk E., DEMİREL G.

ACS Materials Au, 2024 (Scopus) identifier

  • Yayın Türü: Makale / Tam Makale
  • Basım Tarihi: 2024
  • Doi Numarası: 10.1021/acsmaterialsau.4c00005
  • Dergi Adı: ACS Materials Au
  • Derginin Tarandığı İndeksler: Scopus
  • Anahtar Kelimeler: Hydrogel actuator, Self-folding, Smart materials, Spiropyran, Stimuli-responsive polymers
  • Ankara Hacı Bayram Veli Üniversitesi Adresli: Evet

Özet

Light-responsive hydrogel systems have gained significant attention due to their unique ability to undergo controlled and reversible swelling behavior in response to light stimuli. Combining light-responsive hydrogels with nonresponsive polymers offers a unique self-folding feature that can be used in soft robotic actuator designs. However, simple formulation of such systems with rapid response time is still a challenging task. Herein, we demonstrate a simple but versatile bilayer polymeric design combining light-responsive spiropyran-polyacrylamide (SP-PAAm) with polyacrylamide (PAAm) hydrogels. The photochromic spiropyran in our polymer design is a closed-ring, hydrophobic compound and turns into an open-ring, hydrophilic merocyanine isomer under light irradiation. The swelling degree of SP-PAAm and PAAm hydrogels was evaluated using LED lights with different wavelengths and solvent media (e.g., water, ethanol, DMF, and DMSO). We observed that SP-PAAm hydrogels reached a swelling ratio of ∼370% with the illumination of the blue LED in the DMF medium. By combining light-responsive SP-PAAm hydrogels with nonresponsive PAAm, a proof-of-concept demonstration was performed to demonstrate the applicability of our fabricated platforms. Although fabricated one-armed bilayer hydrogels possessed self-folding ability with a folding angle of ∼40° in 30 min, the four-armed bilayer platforms demonstrated more efficient and rapid folding behavior and reached a folding angle of ∼75° in ∼15 min. Given their simplicity and efficiency, we believe that such polymeric designs may offer new avenues for the fields of polymeric actuators and soft robotic systems.