Melting of nanoporous-crystalline and co-crystalline solution cast films of poly(2,6-dimethyl-1,4-phenylene) oxide

The melting behavior of nanoporous-crystalline (NC) and co-crystalline (CC) PPO films is mainly studied by differential scanning calorimetry. For NC films, the dependence of melting behavior on α or β forms as well as on the chemical nature of the guest of precursor CC forms is explored. A relevant result of this contribution is that the use of PPO films with c//orientation also allows establishing melting temperatures of CC phases, being not accessible for other PPO samples. An additional relevant result is the achievement, by suitable annealing procedures on c//oriented CC films, of partially filled CC PPO films with melting temperature just below 300 °C, while NC PPO films always exhibit melting temperatures lower than 265 °C. The reported data, both on NC and CC films, also indicate that molecular volumes most suitable for guests of the α NC form of PPO are in the range 160–230 Å3.