| Abstract
| - The Raman microscopy technique is used to characterize the temperature-induced evolutionof the pore structures of a macroporous N-isopropylacrylamide (NIPA). The gel is synthesized using asuspension of 45 wt % toluene and 55 wt % pregel NIPA solution. The intensity of the band due to theCH2 bending vibration, centered at 1445 cm-1, is used to monitor the distribution of the polymer chaindensity in the lateral plane. It is found that the macroporous gel consists of water-rich areas, which canbe interpreted as the pores, and polymer-rich areas. At room temperature, the average sizes of the poresand the width of polymer-rich areas are 75 μm and 20 μm, respectively. Both the pores and theirsurrounding polymer-rich areas have random geometry, as demonstrated by the Raman microimaging.With increased temperature the size of the pores decreases. This process is accompanied by a narrowingof the polymer-rich areas. At higher temperatures polymer chains bunch together and this processaccelerates rapidly near the volume phase transition temperature (34 °C). Above 36 °C, the pore sizesbecome too small to be resolved using Raman microscopy.
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