Polymerization and Depolymerization of Photoluminescent Polyarylene Chalcogenides

Abstract

Engineering thermoplastics feature high chemical, mechanical, and thermal robustness but often lack advanced functionalities as a result of the harsh conditions required for their synthesis and processing. Herein, we introduce a series of polyarylene chalcogenides (PACs), a classification which encompasses polyphenylene sulfides, polyphenylene oxides, and their derivatives, obtained via the room-temperature polymerization of difluorophthalonitrile and disilyl­(thio)­ether monomers in the presence of fluoride or amine initiators. The PACs contain thioarene-appended phthalonitriles as the key moiety in the polymer chain, which endows them with the additional properties of photoluminescence and dynamic nucleophilic aromatic substitution (SNAr) chemistry while maintaining the thermal robustness of the parent polymers. The materials display delayed fluorescence, and both the emission wavelength and lifetime were rationally tunable through chalcogen substitution. Dynamic SNAr chemistry was exploited in the demonstration of the selective chemical degradation of the PACs, even as highly crosslinked thermosets, at room temperature. The varied properties of this family of PACs make them interesting to a number of applied fields, including organic light-emitting diodes, chemical sensors, and dynamically responsive materials.

Poly(arylene sulfide)s via nucleophilic aromatic substitution reactions of halogenated pyromellitic diimides

“…PMDI-X2 monomers were homocoupled to polymeric and oligomeric polyphenylenes, linked directly through the PMDI core benzene rings, albeit via Yamamoto or Ullman homocoupling as opposed to SNAr. 12 Recently Swager et al 13 demonstrated the SNAr copolymerization of dihalo phthalonitriles as electrophiles and TMS-protected dithiolates as nucleophiles to produce poly(arylene sulfide)s (PAS). The latter nucleophiles had been demonstrated as effective alternatives to dithiolates in their SNAr copolymerization with perfluoroaromatics as electrophiles.…”

“…The latter nucleophiles had been demonstrated as effective alternatives to dithiolates in their SNAr copolymerization with perfluoroaromatics as electrophiles 14 . Swager et al 13 went further to exploit the pseudo‐degenerate ipso ‐substitution 15 of thiolate leaving groups with other thiolates to depolymerize PAS's with small‐molecule thiols as chain limiters and using only a catalytic amount DBU as base at room temperature! This facile reaction under mild conditions with PASs carrying activating electron‐withdrawing groups stands in stark contrast to the cleavage of unactivated and weakly activated diaryl sulfides requiring substantially more forcing conditions (e.g., ≥120°C) 16 .…”

“…Recently Swager et al 13 demonstrated the SNAr copolymerization of dihalo phthalonitriles as electrophiles and TMS‐protected dithiolates as nucleophiles to produce poly(arylene sulfide)s (PAS). The latter nucleophiles had been demonstrated as effective alternatives to dithiolates in their SNAr copolymerization with perfluoroaromatics as electrophiles 14 .…”

Preparation of Recyclable and Versatile Porous Poly(aryl thioether)s by Reversible Pd-Catalyzed C–S/C–S Metathesis

“…By using disilyl thioethers as monomers, they have been able to prepare new poly(arylene sulfide)s under mild conditions that incorporate advanced functions such as photoluminescence and redox responsiveness and, moreover, can be easily degraded. 7 While several sulfur-containing porous materials have been reported in the literature, 8 examples of porous materials containing aryl thioether linkages in the backbone are extremely scarce. 9 Swager and co-workers reported the synthesis of thianthrene-based 2D polymers with high surface areas and interesting redox properties by using dynamic S N Ar reactions of thiocatechols and perfluorinated aromatic compounds ( Scheme 1 b).…”

“…Recently, significant efforts by the Swager group have been directed toward the synthesis of functional PPS analogues. By using disilyl thioethers as monomers, they have been able to prepare new poly­(arylene sulfide)­s under mild conditions that incorporate advanced functions such as photoluminescence and redox responsiveness and, moreover, can be easily degraded . While several sulfur-containing porous materials have been reported in the literature, examples of porous materials containing aryl thioether linkages in the backbone are extremely scarce .…”