Photo-responsive soft actuators based on spiropyran functionalised hydrogels
Dunne, Aishling and Florea, Larisa and Diamond, Dermot (2014) Photo-responsive soft actuators based on spiropyran functionalised hydrogels. In: CIMTEC 2014 – 6th Forum on New Materials, 15-20 June 2014, Montecatini Terme, Italy.
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Hydrogels are a class of polymeric materials, which swell upon hydration. Hydrogels have been used in many areas such as microfluidic systems where they have the function of pumps or valves . Incorporation of photochromic units in hydrogel materials offers new possibilities for the production of photo-responsive soft actuators.
Spiropyrans are one of the most popular classes of photochromic compounds . In acidic environments, the spiropyran gets protonated to form the hydrophilic protonated merocyanine (MCH+) that can be reversed back to the closed hydrophobic spiropyran (SP) by irradiation with white light.
Here we demonstrate that the size and volume of a hydrogel comprising a copolymer of acrylated spiropyran can be reduced when exposed to white lig ht irradiation. This causes the gel to shrink and water is expelled. Different ratios of the SP derivative were investigated in order to achieve increased degree of shrinking and improved kinetics. Finally, the newly obtained photo-actuators were
polymerized “in situ” in microfluidic channels to obtain photo-actuated microfluidic valves suitable for biomedical applications.
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