Polysiloxane-Based Luminescent Elastomers Prepared by Thiol-ene “Click” Chemistry

Supramolecular Elastomers with Excellent Dielectric Properties and High Recyclability Based on the Coordinative Bond

The enhancement in dielectric properties and self-healing ability for dielectric materials has been a challenging subject these years. Herein, a series of self-healed dielectric elastomers by combining the ferric ions and carboxyl-containing poly(sulfone siloxane)s is reported. Experimental results indicate the excellent dielectric properties of obtained elastomers, as the dielectric constant up to 12.8. SEM micrographs exhibit that carboxyl groups and ferric ions can aggregate together to generate clusters, which further result in interfacial polarization. Besides, high polarity dipole units including sulfonyl units and carboxyl groups contribute to dipole polarization. The overlay of the two mentioned polarization eventually results in the high dielectric property. The dielectric constant obviously increases with the contents of carboxyl groups and ferric ions. Moreover, the samples are feasible for recycling and reprocessing with high self-healing efficiency, owing to the reversibility of the coordination bond. A self-healing efficiency of 92.1% in tensile strength of the obtained samples can be reached after 2 h treatment at 60 °C. And the elastomers can also conveniently recover most mechanical properties after solution treatment. This work may offer a promising method for preparing dielectric elastomers with high dielectric properties and self-healing ability.

Organosilicon Fluorescent Materials

In the past few decades, organosilicon fluorescent materials have attracted great attention in the field of fluorescent materials not only due to their abundant and flexible structures, but also because of their intriguing fluorescence properties, distinct from silicon-free fluorescent materials. Considering their unique properties, they have found broad application prospects in the fields of chemosensor, bioimaging, light-emitting diodes, etc. However, a comprehensive review focusing on this field, from the perspective of their catalogs and applications, is still absent. In this review, organosilicon fluorescent materials are classified into two main types, organosilicon small molecules and polymers. The former includes fluorescent aryl silanes and siloxanes, and the latter are mainly fluorescent polysiloxanes. Their synthesis and applications are summarized. In particular, the function of silicon atoms in fluorescent materials is introduced. Finally, the development trend of organosilicon fluorescent materials is prospected.

The Use of the Thiol-Ene Addition Click Reaction in the Chemistry of Organosilicon Compounds: An Alternative or a Supplement to the Classical Hydrosilylation?

This review presents the main achievements in the use of the thiol-ene reaction in the chemistry of silicones. Works are considered, starting from monomers and ending with materials.The main advantages and disadvantages of this reaction are demonstrated using various examples. A critical analysis of the use of this reaction is made in comparison with the hydrosilylation reaction.

Re(I) Complexes as Backbone Substituents and Cross-Linking Agents for Hybrid Luminescent Polysiloxanes and Silicone Rubbers

This study focuses on the synthesis of hybrid luminescent polysiloxanes and silicone rubbers grafted by organometallic rhenium(I) complexes using Cu(I)-catalyzed azido-alkyne cycloaddition (CuAAC). The design of the rhenium(I) complexes includes using a diimine ligand to create an MLCT luminescent center and the introduction of a triple C≡C bond on the periphery of the ligand environment to provide click-reaction capability. Poly(3-azidopropylmethylsiloxane-co-dimethylsiloxane) (N₃-PDMS) was synthesized for incorporation of azide function in polysiloxane chain. [Re(CO)₃(MeCN)(5-(4-ethynylphenyl)-2,2′-bipyridine)]OTf (Re1) luminescent complex was used to prepare a luminescent copolymer with N₃-PDMS (Re1-PDMS), while [Re(CO)₃Cl(5,5′-diethynyl-2,2′-bipyridine)] (Re2) was used as a luminescent cross-linking agent of N₃-PDMS to obtain luminescent silicone rubber (Re2-PDMS). The examination of photophysical properties of the hybrid polymer materials obtained show that emission profile of Re(I) moiety remains unchanged and metallocenter allows to control the creation of polysiloxane-based materials with specified properties.

New Polyhedral Oligomeric Silsesquioxanes-Based Fluorescent Ionic Liquids: Synthesis, Self-Assembly and Application in Sensors for Detecting Nitroaromatic Explosives

In this paper, two different models of hybrid ionic liquids (ILs) based on polyhedral oligomeric silsesquioxanes (POSSs) have been prepared. Additionally, these ILs based on POSSs (ILs-POSSs) exhibited excellent thermal stabilities and low glass transition temperatures. ¹H, 13C, and 29Si nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to confirm the structures of the IL-POSSs. Furthermore, the spherical vesicle structures of two IL-POSSs were observed and were caused by self-assembly behaviors. In addition, we found it very meaningful that these two ILs showed lower detection limits of 2.57 × 10-6 and 3.98 × 10-6 mol/L for detecting picric acid (PA). Moreover, the experimental data revealed that the products have high sensitivity for detecting a series of nitroaromatic compounds-including 4-nitrophenol, 2,4-dinitrophenol, and PA-and relatively comprehensive explosive detection in all of the tests of IL-POSSs with nitroaromatic compounds thus far. Additionally, the data indicate that these two new ILs have great potential for the detection of explosives. Therefore, our work may provide new materials including ILs as fluorescent sensors in detecting nitroaromatic explosives.

Unexpected self-assembly, photoluminescence behavior, and film-forming properties of polysiloxane-based imidazolium ionic liquids prepared by one-pot thiol–ene reaction

The synthesis of a series of polysiloxane-based ionic liquids (PNLs) is reported via straightforward thiol–ene reaction with high yield using three kinds of imidazolium ionic liquid monomers.

Color-Transformable Silicone Elastomers Prepared by Thiol-Ene Reaction with Potential Application in UV-LEDs

A series of high-efficiency, full-color fluorescent elastomers based on polysiloxane matrix prepared by an easy thiol-ene "click" reaction is reported here. It is found for the first time that the same elastomer can emit transformable colors by conveniently altering the excitation wavelength because of the effect of energy transfer and the "fluorescence switch" of lanthanide ions. A fluent change in emission colors can also be feasible and conveniently reproducible by varying the stoichiometric ratio of lanthanide ions and rhodamine-B in solution and in polymer elastomers. The obtained elastomers are further coated onto commercially available UV-LED cells from the solution medium followed by an in situ cross-linking step.

A new approach for the synthesis of sulfur-bridged polysiloxanes via thiol–ene “click” reaction and their post-functionalization to obtain luminescent materials

A novel polymerization method for preparing well defined sulfur containing siloxane polymers.

Ultrafast diffusion-controlled thiol–ene based crosslinking of silicone elastomers with tailored mechanical properties for biomedical applications

Thiol-ene coupling enables the metal-free ultra-fast (seconds) crosslinking of polysiloxanes.

A new route to achieve the side-chain-type sulfone-containing polysiloxanes via sulfide oxidation-induced cleavage and rearrangement of Si–O–Si bonds with fine selectivity toward cyclosiloxanes

A novel approach to obtain polysiloxanes containing sulfone groups was carried out.