1 research outputs found
Tetra-Sensitive Graft Copolymer Gels as Active Material of Chemomechanical Valves
Stimuli-responsive
hydrogels combine sensor and actuator properties by converting an
environmental stimulus into mechanical work. Those materials are highly
interesting for applications as a chemomechanical valve in microsystem
technologies. However, studies about key characteristics of hydrogels
for this application are comparatively rare, and further research
is needed to emphasize their real potential. The first part of this
study depicts the synthesis of grafted hydrogels based on a poly(<i>N</i>-isopropylacrylamide) backbone and pH-sensitive poly(acrylic
acid) graft chains. The chosen approach of grafted hydrogels provides
the preparation of multiresponsive hydrogels, which retain temperature
sensitivity besides being pH-responsive. A pronounced salt and solvent
response is additionally achieved. Key characteristics for an application
as a chemomechanical valve of the graft hydrogels are revealed: (1)
independently addressable response to all stimuli, (2) significant
volume change, (3) sharp transition, (4) reversible swelling–shrinking
behavior, and (5) accelerated response time. To prove the concept
of multiresponsive hydrogels for flow control, a <i>net</i>-poly(<i>N</i>-acrylamide)-<i>g</i>-poly(acrylic
acid) hydrogel containing 0.6 mol % poly(acrylic acid)-vinyl is employed
as active material for chemomechanical valves. Remarkably, the chemomechanical
valve can be opened and closed in a fluidic platform with four different
stimuli