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Diselenide-containing polymers are facilely synthesized from polymers prepared by atom transfer radical polymerization (ATRP). Benefiting from the ATRP technology, this protocol provides a flexible route for controlling the polymer structure, which allows for a great variety of architectures of selenium-containing polymer materials for applications in various fields. The oxidative and reductive responsive behavior of the obtained diselenide-containing polymers is also investigated. [ABSTRACT FROM AUTHOR]

A facile soap-free miniemulsion polymerization of methyl methacrylate (MMA) was successfully carried out via a reverse ATRP technique, using a water-soluble potassium persulfate (KPS) or 2,2′-azobis(2-methylpropionamidine) dihydrochloride (V-50) both as the initiator and the stabilizer, and using an oil-soluble N,N-n-butyldithiocarbamate copper (Cu(S2CN(C4H9)2)2) as the catalyst without adding any additional ligand. Polymerization results demonstrated the 'living'/controlled characteristics of ATRP and the resultant latexes showed good colloidal stability with average particle size around 300-700 nm in diameter. The monomer droplet nucleation mechanism was proposed. NMR spectroscopy and chain-extension experiments under UV light irradiation confirmed the attachment and livingness of UV light sensitive SC(S)N(C4H9)2 group in the chain end. [ABSTRACT FROM AUTHOR]

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]

Butyl acrylate is polymerized in the living way under the irradiation of purple light-emitting diode (LED) or sunlight without photocatalyst at ambient temperature. 2-((Phenoxycarbonothioyl)thio) ethyl propanoate) is exclusively added and acted as an initiator and a chain transfer agent simultaneously in the current system. Poly(butyl acrylate) with well-regulated molecular weight and relatively narrow molecular weight distribution ( Ð < 1.30) is synthesized. High conversion (>95%) can be achieved within several minutes. Polymerization shows oxygen tolerance. Near quantitative end-group fidelity of polymer is demonstrated by 1H NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectra. [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]

Vinyl acetate is polymerized in the living way under the irradiation of blue light-emitting diodes (LEDs) or sunlight without photocatalyst at ambient temperature. 2-(Ethoxycarbonothioyl)sulfanyl propanoate is exclusively added and acts as initiator and chain transfer agent simultaneously in the current system. Poly(vinyl acetate) with well-regulated molecular weight and narrow molecular weight distribution (Ð < 1.30) is synthesized. Near quantitative end group fidelity of polymer is demonstrated by nuclear magnetic resonance (NMR) and matrix-assisteed laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). [ABSTRACT FROM AUTHOR]

Herein, the first example of photosensitive cyclic amphiphilic homopolymers consisting of multiple biphenyl azobenzene chromophores in the cyclic main chain tethered with hydrophilic tetraethylene glycol monomethyl ether units is presented. The synthetic approach involves sequentially performed thermal catalyzed 'click' step-growth polymerization in bulk, and Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) intramolecular cyclization from α-alkyne/ω-azide linear precursors. It is observed that such amphiphilic macrocycles exhibit increased glass transition temperatures ( Tg), slightly faster trans-cis-trans photoisomerization, and enhanced fluorescence emission intensity compared with the corresponding linear polymers. In addition, the cyclic amphiphilic homopolymers self-assemble into spherical nanoparticles with smaller sizes which possess slower photoresponsive behaviors in a tetrahydrofuran/water mixture compared with those of the linear ones. All these interesting observations suggest that the cyclic topology has a great influence on the physical properties and self-assembly behavior of these photoresponsive amphiphilic macrocycles in general. [ABSTRACT FROM AUTHOR]

An iron-mediated reverse ATRP of methyl methacrylate (MMA) is successfully carried out in water in the absence of any dispersants, using a water-soluble 2,2′-azobis(2-methylpropionamidine) dihydrochloride (V-50) as the initiator and the stabilizer, and using an oil-soluble N,N-butyldithiocarbamate ferrum (Fe(S2CN(C4H9)2)3) as the catalyst without adding any additional ligands. Micron-sized PMMA particles with UV light-sensitive -S2CN(C4H9)2 end group are obtained, and monomer droplet nucleation and suspension polymerization mechanism are proposed. Polymerization results demonstrated typical 'living'/controlled characteristics of ATRP: first-order polymerization kinetics, linear increase of molecular weights with monomer conversion and narrow molecular weight distributions for the resultant PMMA particles. NMR spectroscopy and chain-extension experiments under UV light irradiation confirm the attachment and livingness of UV light-sensitive -S2CN(C4H9)2 group in the chain end. [ABSTRACT FROM AUTHOR]