Thermal and photocatalytic stability enhancement mechanism of poly(propylene carbonate) due to Cu(I) impurities

The thermal and photolytic decomposition of poly(propylene carbonate) (PPC) in the presence of a photoacid generator (PAG) was studied. The mechanism of previously observed shifts in the decomposition temperature of PPC was investigated. The decomposition temperature of PPC can be altered when PPC/PAG films contact copper metal. X-ray photoelectron spectroscopy (XPS) analysis showed that a small amount Cu(I) was incorporated into the PPC/PAG film causing the increased stability and the Cu(I) concentration was similar to that of the PAG. PPC/PAG temperature stability was studied for a number of iodonium and sulfonium-based PAGs. Every iodonium-based PAG showed a PPC decomposition temperature shift and no sulfonium-based PAG showed the thermal stability effect. It appears that Cu(I) interacts with iodonium in the cation of the PAG causing a change in the acid creation mechanism of the PAG.