Both the porous structure of the hydrogel and the assemble effect of gold nanorods (AuNRs) within the PNIPAM (poly(N-isopropylacrylamide)) fibers facilitate fast thermal and photoresponse, and high structural integrity even in acidic or basic condition.
Besides the porous structure, AuNRs inside the hydrogel fibers were assembled and aligned along the long axial direction of the fibers.
The synergistic effect of polymers and colloidal nanoparticles assures new classes of composite materials and have been intensively investigated due to their unique properties and fascinating applications in many areas.
The polymer component plays a key role in modulating the properties of the inorganic nanoparticles relating to the optical, catalytic, electrical, sensing, and biomedical fields.
These composite materials present a higher degree of chemical or physical complexity than the isolated components.
The most significant challenge for thermoresponsive hydrogels is to achieve both fast response and structural integrity during the repeating volume changes. The researchers addresses this issue by using fibrous materials prepared by electrospinning that possess high specific area and large porosity. The porous structures in the hydrogel is conductive to water pathways, which can greatly promote the response rate.
The team notes that, simply by steaming gold on the surfaces, this cross-linked composite hydrogel can be used as one novel kind of thermal/photocontrolled switch.
The prepared AuNRs/PNIPAM composite hydrogel also has high valuable potential applications in a 'smart' sensor, nanoreactor, catalysis, and artificial muscle. In addition, other nanoparticles, such as magnetic nanoparticles or quantum dots, also could be incorporated with PNIPAM by this facile method to produce novel stimuli-responsive functional materials.