Temperature-responsive one-dimensional nanogels formed by the cross-linker-aided single particle nanofabrication technique.

A single particle nanofabrication technique was successfully applied to the fabrication of homogeneous poly(N-isopropylacrylamide) (PNIPAAm) 1D nanogels over a large area, using N,N'-methylene-bis-acrylamide (MBAAm) as a cross-linker. The PNIPAAm 1D nanogels with high aspect ratio over 130 were formed uniformly on the substrate, and the mechanical strength and the length of the 1D nanogels can be easily controlled by adjusting the MBAAm content. The 1D nanogels were transformed from the non-aggregated to aggregated forms over a lower critical solution temperature (LCST) of approximately 32 °C in water. Precise trace of the temperature induced change in the size of the 1D nanogel was well interpreted by the coil-to-globule transition of PNIPAAm, which was clearly visualized in the present study. This is the first report of uniform shape change for a 1D nanogel by external stimulus over a large area.