Guest induced transition from β to α nanoporous crystalline forms of PPO. (20th January 2020)

• Record Type: Journal Article
• Authors: Nagendra, Baku; Cozzolino, Antonietta; Golla, Manohar; Daniel, Christophe; Rizzo, Paola; Guerra, Gaetano
• Is Part Of: Polymer. Volume 187(2020)
• Publication Date: 2020-01-20
• Subjects: Co-crystalline phases -- β→α transition -- Films -- Aerogels -- X-ray diffraction -- FTIR; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2019.122083
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: The stability of α and β nanoporous-crystalline (NC) forms of Poly(2, 6-dimethyl-1, 4-phenylene) oxide (PPO), in the presence of guest molecules leading to crystallization in α and β -form ( α and β -guests), is explored. Sorption of liquid guests at 30 °C and 60 °C is studied both for NC films and NC aerogels. WAXD and FTIR characterizations show that, for all considered conditions, NC α -phases after guest sorption/desorption remain unaltered. NC β -phases, on the contrary, after α -guest sorption can be transformed in co-crystalline (CC) α -phases that after guest desorption are transformed in NC α -phases. All conducted experiments also show that possible planar orientations of NC films (c//or c⊥ orientations) remain essentially unaltered, after sorption of all considered guest molecules. The presently discovered β → α transition constitutes a route to obtain unoriented α -form films, which till now were not available by known preparation procedures. Graphical abstract: Image 109337 Highlights: Nanoporous-crystalline β . →α transition induced by α -guest molecules Nanoporous-crystalline α -form being stable after β -guest sorption/desorption. β .→ α transition constitutes a route to obtain presently unavailable unoriented α -form films Planar orientations (c//or c⊥) unaltered by sorption/desorption of all guest molecules.