Search

Selenium‐containing monomer (p‐phenylseleno) styrene (p‐PhSeSt) is polymerized by reversible addition‐fragmentation chain transfer polymerization. Polymer, (P(p‐PhSeSt)), with controlled molecular weight and narrow molecular weight is obtained. The selenide moiety in obtained P(p‐PhSeSt) can be selectively oxidized to selenoxide or selenone groups by H2O2 or NaClO, respectively. These oxidized groups can be further reduced to selenide by Na2S2O4. The structure changing of polymers during such redox cycle is characterized by nuclear magnetic resonance, X‐ray photoelectron spectroscopy, and size exclusion chromatography. Properties, such as thermal performance, glass transition temperature, water contact angles, and refractive indices, of the resulting polymers are systematically investigated before and after oxidation. In addition, SiO2 inverse opal photonic crystal (IOPC) is fabricated by sacrificial polymer colloidal template method. Owing to changes of the RIs of P(p‐PhSeSt) after selective oxidation, the predictable change of PC bandgap as a redox‐responsive PC sensor is successfully realized, which provides new perspectives for modulating photonic crystals. [ABSTRACT FROM AUTHOR]

Pendant selenium‐containing maleimide polymers with different selenium contents are synthesized via a radical copolymerization of styrene and N‐butylmaleimide phenyl selenide. The polymer structures are characterized by nuclear magnetic resonance, gel permeation chromatography, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and scanning electron microscopy with an energy‐dispersive spectrometer, which results in the desired structures and selenium contents. The refractive indices of the polymers, which change as a function of different contents of selenium and oxidative stimuli by H2O2 or O3, are investigated. Finally, a photonic crystal (PC) is prepared based on the selenium‐containing polymer. The visible color changes of the PC are investigated as a function of different concentrations and contact times of O3. [ABSTRACT FROM AUTHOR]

The application of selenol-X chemistry in nucleophilic substitution and Se-Michael addition reactions for polymer chain end modification is presented. Selenol-labeled polystyrene can easily react with alkyl halides, methyl methacrylate, methyl acrylate, pentafluorostyrene, etc. The mild conditions make it attractive for the synthesis of macromonomers. The resulting polymers are analyzed and characterized by UV, size-exclusion chromatography (SEC), NMR, and matrix assisted laser desorption/ionization time of flight mass spectroscopy. [ABSTRACT FROM AUTHOR]

Diselenide-containing polymers have attracted more and more attention due to their redox sensitivity and bioapplication. In this work, a bifunctional diselenocarbonate is prepared and used to mediate the reversible addition-fragmentation chain transfer (RAFT) polymerization, producing α,ω-selenocarbonate-labeled telechelic polystyrene. Based on effective aminolysis of the terminal selenocarbonates and the followed spontaneous oxidation coupling reaction of diselenols, monoblock cyclic polystyrene linked by one diselenide bond and multiblock cyclic copolymer linked by several diselenide bonds are prepared by manipulating the concentration of α,ω-telechelic polystyrene in solution. The progress of aminolysis and the subsequent spontaneous oxidation of selenols to diselenides are monitored by UV-vis, gel permeation chromatography (GPC), and NMR characterizations, confirming the cyclic topologies of the resultant polymers (monocyclic or multiblock cyclic polymer). The monoblock cyclic or multiblock polymers show redox sensitivity, which can be converted to linear polymer by reducing or oxidizing agent. Moreover, the obtained monoblock cyclic polymer or multiblock cyclic copolymer can be transformed to each other under UV irradiation by adjusting the concentration of the cyclic polystyrene. For the first time, this work provides an alternative and promising approach to realize the topological transformation of polymers by installing multiresponsive diselenide moities into the backbone of cyclic polymer. [ABSTRACT FROM AUTHOR]

Herein, p -phenylseleno styrene (p -PhSeSt) and 4-(1,2,2-triphenylvinyl)phenyl acrylate (TPE-a) were copolymerized by photo-induced reversible addition-fragmentation chain transfer (RAFT) polymerization under blue light at room temperature. The selenide moiety in resulting copolymers could be selectively oxidized to selenoxide or selenone groups by H 2 O 2 or NaClO, respectively, which caused the changing of structure and performance of the copolymer. The structure changing of copolymers during the oxidation was characterized by nuclear magnetic resonance and size exclusion chromatography. Properties of the resulting polymers were systematically investigated before and after oxidation, such as thermal performance, glass transition temperature, water contact angles and refractive indices. In addition, due to the change of hydrophilicity and hydrophobicity of the polymers in aqueous solution after oxidation, the detection of Au3+ and nitrobenzene were successfully realized, constructing a versatile and multifunctional fluorescent probe sensor, which provides potential application prospects for the detection of oxidations. [Display omitted] • Selenium-containing polymers with controlled oxidative behavior was synthesized. • Oxidative responsive property was combined with AIE functionality. • Fluorescent probes for the detection of Au3+ and nitroaromatic were constructed. [ABSTRACT FROM AUTHOR]

• High refractive index polyimides with as high as more than 1.8 of RI value were developed. • Solubility was greatly improved realizing the use of easy processing method. • PI showed high-low-high cycles of RI in film state under redox condition. Soluble high refractive index polyimides have extensive applications in optical devices due to their ease of processing and versatility. In this work, selenide-containing polyimides were designed and synthesized via amine-dianhydride polycondensation. Two selenide containing diamines, e.g. bis(3-trifluoromethyl-4-aminophenyl)selenide (BTFAPS) and bis(4-aminophenyl)selenide (BAPS) were reacted with 4,4′-(Hexafluoroisopropylidene)diphthalic anhydride (6FDA) for the preparation of selenide containing polyimides. Comparison with its oxygen and sulfur counterparts, the selenide-containing PIs have better solubility, higher refractive index, and can bring redox responsiveness. This is due to the trifluoromethyl base, which possesses a large free volume, and the selenium element, which has a higher molar refraction and redox activities than even sulfur. Various techniques, such as nuclear magnetic resonance, gel permeation chromatography, Fourier transformed infrared spectroscopy and wide angle X-ray diffraction were used for characterizing the polymers structure. Differential scanning calorimetry, thermogravimetric analysis, ultraviolet-visible spectroscopy, spectroscopic ellipsometry and X-ray photoelectron spectroscopy were used to characterize the properties of the polymers. [ABSTRACT FROM AUTHOR]