Figure 8 shows TGA thermograms of neat P(MMA-co-BA), nano-ZnO/P(MMA-co-BA) nanocomposites before and after hydrothermal treatment at pH=10 for 24 hrs. The decomposition temperature of the neat P(MMA-co-BA) copolymer is lower than those of the nano-ZnO/P(MMA-co-BA) and the hydrothermal treated one. The 10% weight loss of the neat P(MMA-co-BA) copolymer was observed at around 304 °C while those of the nanocomposites were observed at around 309 and 322 °C for untreated and hydrothermal treated nano-ZnO/P(MMA-co-BA), respectively. The presence of nano-ZnO in the nanocomposites could improve their thermal stability because the ZnO having a greater heat capacity than
the polymer matrix. The ZnO could absorb the heat transmitted from the surroundings and retard the heat transfer within the nanocomposites, bringing about the polymer backbone was hindered from the direct heat impact. In case of hydrothermal treated nanocomposites, the significant enhancement of thermal stability was attributed to the synergistic actions of the nano-ZnO in the P(MMA-co-BA) matrix and the layer of hydrothermal grown ZnO on the nanocomposite surface, acting as a heat barrier to postponethe degradation of the P(MMA-co-BA) matrix.