Photocrosslinking of thin films of temperature-sensitive polymers

The use of polymeric materials with temperature-dependent degrees of swelli ng (especially polymers that exhibit lower critical solution temperature (L CST) behaviour in aqueous solutions) in microsystems requires the preparati on and patterning of layers in the mu m range. Copolymers based on N-isopro pylacrylamide were modified with a stilbazolium salt chromophore to yield p hotocrosslinkable temperature-sensitive polymers. The chromophore and the p olymers were characterized by UV, IR, H-1-NMR (nuclear magnetic resonance) and C-13-NMR spectra. The resulting polymers showed LCST behaviour, which w as measured by. differential scanning calorimetry. The photocrosslinking pr operties were studied by UV irradiation of the thin pms and measurement of the changes in the UV absorption spectra. By irradiation of thin films thro ugh a mask it was possible to obtain patterned networks in the mu m range ( 20 mu m space width and greater than or equal to 50 mu m line width). The r esulting patterned networks showed temperature-dependent swelling propertie s in aqueous media. Copyright (C) 1999 John Wiley & Sons, Ltd.