Functional, Redox-Responsive Poly(phenylene sulfide)-Based Gels

Abstract

Poly(p-phenylene sulfide) (PPS) is a highly robust thermoplastic with outstanding thermal and chemical stability. However, development of functional PPS-based materials is hampered by harsh synthetic conditions and poor solubility. As an alternative to nucleophilic aromatic substitution (SNAr), we report herein on the use of benzoquinone conjugate addition chemistry to prepare PPS-derivatives bearing redoxactive hydroquinones in the polymer backbone. Specifically, we utilize thiosilanes as thiol surrogates in order to attenuate unproductive redox-isomerization reactions and to provide a thermodynamic driving force for polymerization. The silyl transfer conjugate addition process results in a poly(phenylene silylhydroquinone sulfide) (PPSHS) amenable to several divergent modes of functionalization. Notably, the so-formed PPSHS exist as gels which swell organic solvents and exhibit distinct changes in color and swelling upon redox changes. By repeated cycling of oxidation and thiol conjugate addition, the crosslinked networks can be depolymerized under ambient conditions. Finally, we prepared an interpenetrating polymer network (IPN) comprised of PPSHS and cross-linked poly(n-butyl acrylate) which exhibits a significant enhancement in thermomechanical properties over the base materials.

Polymerization and Depolymerization of Photoluminescent Polyarylene Chalcogenides

“…Trimethylsilyl (TMS)-protected dithiols were recently demonstrated by Hedrick and co-workers to be effective monomers for site-selective polymerization with aryl fluoride monomers bearing multiple reactive sites (Figure B), and these reactions proceeded under homogeneous conditions with the exothermic generation of TMS–F . The disilyl­(thio)­ether monomers 2 were obtained by reacting 4,4′-thiobisbenzenethiol ( 1a ) or 4,4′-thiodiphenol ( 1b ) with excess hexamethyldisilazane or triisopropylsilyl chloride under various conditions, followed by the removal of excess silyl chloride under reduced pressure (Figure A). ,, With a variety of fluoride or amine initiators, disilylthioether 2a and difluorophthalonitrile 3a afforded PAC 4a in variable yields but with generally improved dispersities (Table , entries 2–9). 1 H NMR spectra of 4a from entry 6 indicated largely uniform regioisomerism, as evidenced by four distinct aromatic signals (Figure S41); however, surprisingly large dispersities observed in these cases emphasizes that minor degrees of branching are sufficient to effect broadening in the molecular weight distribution.…”

“…Specifically, industrial syntheses proceed by nucleophilic aromatic substitution (S N Ar) at high temperatures (>200 °C) and in the presence of strong bases, whereas melt processing requires similarly high temperatures (>280 °C for PPS) . Milder polymerization strategies to achieve PACs have been developed, including oxidative coupling, Ullmann condensation, Michael addition reactions, or S N Ar reactions with especially reactive nucleophilic or electrophilic monomers. , In doing so, more advanced chemical moieties have been appended to the PAC scaffold, enabling advanced applications including chemical sensing, gas separation, and proton exchange/transport . However, the scope of truly mild, room-temperature polymerization methods to achieve PACs remains limited.…”

Energy Storage Application of All-Organic Polymer Dielectrics: A Review

“…As a result, it is a widely used polymer material. However, its dielectric loss is less than 0.001 at 1 kHz at 100 • C. As a result, modifications to the molecular chain are required to make it stable at high temperatures [67][68][69].…”

Application of Bulky NHC–Rhodium Complexes in Efficient S–Si and S–S Bond Forming Reactions

“… 3 Recently, the use of silylthioethers in the process of creating redox-responsive poly(phenylene sulfide)-based gels has been described. 4 Despite the great practical importance of silylthioethers, only a limited number of methods for their synthesis have been presented as yet. 5 It is possible to prepare these compounds in reactions of chlorosilanes with metal sulfides.…”

“…The Si–S bond can also be activated in a reaction with aryl chlorides giving diaryl thioethers . Recently, the use of silylthioethers in the process of creating redox-responsive poly­(phenylene sulfide)-based gels has been described . Despite the great practical importance of silylthioethers, only a limited number of methods for their synthesis have been presented as yet .…”