Multiwalled carbon nanotubes (MWCNTs)/poly(N-isopropylacrylamide-co-acrylic acid) composite microhydrogels are simply synthesized with controllable size distribution via a microfluidic reactor system. Monomers (N-isopropylacrylamide and acrylic acid) are rapidly copolymerized (about 3 s) with the embedding of nanoscaled inorganic materials (MWCNTs and hectorites) in microfluidic channels. MWCNTs/hectorites act as "molecular heater" and inorganic crosslinkers in this hydrogel system. As a result, microminiaturization, multifunctionalizaion, and modification of traditional polymer hydrogels are realized simultaneously. Fourier transform infrared spectroscopy is used to confirm polymerization and environment-sensitive tests are done as well. The resultant microgels exhibit dual near-infrared and pH response with good reversibility, indicating their potential applications in microreactor fields. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127:2422-2426, 2013