Thermal Properties of Plasma Deposited Methyl Methacrylate Films in an Atmospheric DBD Reactor

Methyl methacrylate (MMA) is deposited on aluminum substrates using atmospheric dielectric barrier discharge plasma. The thermal properties of plasma deposited MMA (pdMMA) films of 0.5 to 1 μm thickness are evaluated as a function of plasma power and precursor mass feed. Thermogravimetric analysis indicates a low molecular weight fraction in all pdMMA films, which lowers their thermal stability. Differential scanning calorimetry (DSC) is used to quantify the glass transition (Tg) and residual reactivity of the pdMMA thin films. For all plasma conditions, the Tg remains inferior to conventional PMMA, and ranges from 20 °C in the monomer-deficient domain to 56 °C in the energy-deficient domain. A residual reactivity is measured in the first DSC heating of all pdMMA films, showing an exothermicity up to −160 J g−1.