Polyphosphazenes and Cyclotriphosphazenes with Propeller-like Tetraphenylethyleneoxy Side Groups: Tuning Mechanical and Optoelectronic Properties

Abstract

A new class of polyphosphazene elastomers has been synthesized that combines a −PN– backbone with both 2,2,2-trifluoroethoxy and tetraphenyl­ethyleneoxy (TPEO) side groups. The polymer syntheses and photoproperties were first modeled using small molecule cyclic phosphazenes, and these were then applied to the high polymers. The TPEO groups confer useful mechanical and photophysical properties on the polymers. Thus, those polyphosphazenes with the more rigid bidentate TPEO side groups have higher fluorescence quantum yields than counterparts with monodentate TPEO groups. Different TPEO substituents also allow tuning of the side-group interactions to modify the elastomeric properties of the polymers. For example, the two-dimensional TPEO unit is a stronger physical cross-linker than the comparable cross-linkers used in earlier polyphosphazene elastomers. Thus, the elastomeric polymers containing the two-dimensional TPEO exhibit greatly improved mechanical properties compared to the previous ones. Moreover, hybrid materials that combine the new elastomers with single-walled carbon nanotubes (SWNTs) allow the fabrication of stretchable electronics with mechanically responsive properties.

Thiophene‐based polyphosphazenes with tunable optoelectronic properties

“…This exerts a significant effect on the overall properties of the polymeric product 19 . Recently, we also reported that rigid conjugated side groups interconnect with each other via steric and intermolecular pi–pi interactions, which affect the optical and physicochemical properties of the polyphosphazene 20,22–24 . In this current study, two thiophene‐based polyphosphazenes were synthesized.…”

“…19 Polyphosphazenes that contain other electroactive side groups have also been synthesized, and these polymers show excellent optical and electrical properties. [20][21] In a previous study, it was found that thiophene side groups attached to the backbone of a polyphosphazene can be oxidized and polymerized. This exerts a significant effect on the overall properties of the polymeric product.…”

“…19 Recently, we also reported that rigid conjugated side groups interconnect with each other via steric and intermolecular pi-pi interactions, which affect the optical and physicochemical properties of the polyphosphazene. 20,[22][23][24] In this current study, two thiophene-based polyphosphazenes were synthesized. These polymers exhibit synergistic properties uncommon to either of the merging species.…”

“…In earlier work, thiophene units have been linked as side groups to phosphazene polymers to afford materials that are intrinsic semiconductors 19 . Polyphosphazenes that contain other electroactive side groups have also been synthesized, and these polymers show excellent optical and electrical properties 20–21 . In a previous study, it was found that thiophene side groups attached to the backbone of a polyphosphazene can be oxidized and polymerized.…”

Effect of hybrid cross‐linked polyphosphazene microspheres on ablative and mechanical properties of ethylene propylene diene monomer

“…Polyphosphazene is an organic–inorganic hybrid material with many excellent properties. The research on polyphosphazene is very active, which covers many aspects such as special rubber and elastic materials, flame retardant materials, biomedical materials, and optoelectronic materials 22–26 …”