REFLECTION-ABSORPTION INFRARED-SPECTROSCOPY STUDY OF POLYACRYLONITRILE ON COPPER AT ELEVATED-TEMPERATURE

Reflection-absorption infrared spectroscopy (PAIR) has been used to in vestigate the chemical structural changes in Polyacrylonitrile (PAN) f ilm adsorbed on copper at 200 degrees C for different time. The format ion of an almost fully conjugated C-C=C backbone occurs after heating for only 2 h due to the catalytic effect of copper. The freely danglin g cyano groups in PAN molecules initially coordinate to copper surface through the triple bond in pi-bonded orientation, then convert to sig ma-bonding through the donation of the lone pair of electrons of nitro gen. It is suggested that this transition of the types of coordination would relate to the different geometries of PAN on copper during heat ing. Since the nitrile complexing and cyclization occur at the same ti me, the reaction process for the pyrolysis of PAN on copper surface is different from that in the bulk.