Axial Orientation of Co-Crystalline Phases of Poly(2,6-Dimethyl-1,4-Phenylene)Oxide Films

Manohar Golla; Baku Nagendra; Christophe Daniel; Paola Rizzo; Gaetano Guerra

doi:10.3390/polym12102394

Axial Orientation of Co-Crystalline Phases of Poly(2,6-Dimethyl-1,4-Phenylene)Oxide Films

Polymers (Basel). 2020 Oct 17;12(10):E2394. doi: 10.3390/polym12102394.

Authors

Manohar Golla¹, Baku Nagendra¹, Christophe Daniel¹, Paola Rizzo¹, Gaetano Guerra¹

Affiliation

¹ Chemistry and Biology Department, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy.

Abstract

Films exhibiting co-crystalline (CC) phases between a polymer host and low-molecular-mass guest molecules are relevant for many applications. As is usual for semi-crystalline polymers, axially oriented films can give relevant information on the crystalline structure, both by Wide Angle X-ray diffraction fiber patterns and by polarized Fourier-transform infrared spectroscopy. Axially oriented CC phases of poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) with 1,3,5-trimethylbenzene (mesitylene) can be simply obtained by the stretching of CC PPO films. In fact, due to the plasticization effect of this highly boiling guest, PPO orientation can occur in a stretching temperature range (170-175 °C) nearly 50 °C lower than that generally needed for PPO films (220-230 °C). This low stretching temperature range allows avoidance of polymer oxidation, as well as formation of the mesomorphic dense γ PPO phase. Axially oriented CC phases of PPO with toluene, i.e., with a more volatile guest, can be instead obtained by the stretching (in the same low temperature range: 170-175 °C) of CC PPO blend films with polystyrene.

Keywords: WAXD; atactic polystyrene; host-guest orientation; mesitylene; nanoporous-crystalline; polarized FTIR; poly(2,6-dimethyl-1,4-phenylene)oxide; toluene; α form.