On complexation between methyl cellulose and ammonium nitrate

Films of methyl cellulose (MC) doped with ammonium nitrate (NH4NO3) salt were prepared by solution casting. From X-ray diffraction, it can be inferred that films of pure MC and MC doped with 5 to 25 wt-% NH4NO3 are amorphous. A small peak at 2θ ∼8° indicates that there is interaction between MC and NH4NO3 and a complex has formed. Pure MC has a conductivity of 3·08 × 10–11 S cm–1 at room temperature and the conductivity of MC doped with 25 wt-% NH4NO3 is 2·10 × 10–6 S cm–1. The increase in conductivity is attributed to the increase in amorphousity and to the increase in number of mobile cations. However, for the sample doped with 30 wt-% NH4NO3, some of the salt has recrystallised out of the polymer host. This is evidenced from the X-ray diffractogram. Recrystallisation of the salt reduces the number of mobile ions for conduction and resulted in a decrease in conductivity. The highest conducting sample was used as an electrolyte in an electric double layer capacitor.