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Photoinduced atom transfer radical polymerization of methyl methacrylate with conducting polymer nanostructures as photocatalyst
摘要： Light-mediated control/living radical polymerization (CLRP) provides a convenient method to synthesize polymers with controlled molecular weight and narrow molecular weight distribution. However, high-energy wavelengths (such as UV light) and blue light are needed to initiate the polymerization, leading to unwanted side reactions. To overcome these defects, the use of long-wavelength light for light-mediated CLRP is highly desirable. In this work, photoinduced atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully carried out for the synthesis of polyMMA (PMMA) with predictable molecular weights (Mn,GPC) and narrow molecular weight distribution (Mw/Mn). This was achieved using one-dimensional nanopoly(diphenyl butadiyne) (nanoPDPB) as photocatalyst, which activated the dormant alkyl bromides initiator to reversibly produce propagating radicals at ambient temperature. Initiation and termination of polymerization were regulated by periods of light. The polymerization of MMA was accomplished by the radicals generated in the redox reaction of nanoPDPB with EBP. Both 1H nuclear magnetic resonance (1H NMR) spectroscopy and chain-end extension polymerization show highly preserved bromine chain-end functionality in the synthesized PMMA. nanoPDPB displays remarkable photophysical properties in the visible light region. The polymerization of MMA followed the first-order kinetics and the evolution of the Mn,GPC versus monomer conversion and Mw/Mn demonstrated the well-controlled polymerization process. The living character of heterogeneous photomediated ATRP with nanoPDPB as photocatalyst was successfully confirmed.
关键词： Poly(diphenyl butadiyne),Control/living radical polymerization,Living radical polymerization,Photocatalyst,Atom transfer radical polymerization
更新于2025-09-19 17:15:36
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Synthesis of organic–inorganic hybrids <i>via</i> a high-pressure-ramp process: the effect of inorganic nanoparticle loading on structural and photochromic properties
摘要： Organic polymerization remains a limiting step in the preparation of organic–inorganic hybrid materials with a strong concentration of the inorganic component. In this work, a high-pressure-ramp process was applied to achieve pHEMA–TiO2 nanoparticulate solids with an unprecedentedly high concentration (12 mol l?1) of the inorganic component, which is four times higher than that obtained after radical polymerization induced thermally or by photons. The inorganic nanoparticles underwent morphological and structural changes with an increase of Ti concentration above 1.5 mol l?1: they slightly coarsen and crystallize into an anatase polymorph. The material possesses a strong photochromic response related to the electron–hole separation at the organic–inorganic interface and can store 1e? per 5 Ti atoms. The electron storage capacity of the titania nanoparticles decreases upon crystallization.
关键词： high-pressure-ramp process,polymerization,TiO2 nanoparticles,photochromic properties,organic–inorganic hybrids
更新于2025-09-19 17:15:36
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An efficient room-temperature synthesis of highly phosphorescent styrenic Pt( <scp>ii</scp> ) complexes and their polymerization by ATRP
摘要： Cyclometalated Pt(II) complexes are among the most efficient phosphorescent materials, yet their incorporation into polymers remains rare. This is largely due to challenges with existing synthetic methods, characterized by long reaction times, excess reagents, high temperatures and low product yields. Here we demonstrate a stoichiometric, one-pot cyclometalation protocol which gives Pt-containing styrenic monomers in short reaction times at ambient temperature with improved yields. These monomers were then incorporated into highly phosphorescent polymers by ATRP, giving materials with Mn ～ 10 000 and ? = 1.12–1.15. The preparation of block copolymers is also demonstrated, as well as the synthesis of mixed-colour phosphorescent films using partial energy transfer between platinum chromophores. This cyclometalation protocol should make the preparation of Pt(II) metallopolymers significantly more accessible, opening the door to a broad range of applications in optoelectronics.
关键词： optoelectronics,Pt(II) complexes,phosphorescent,polymerization,ATRP
更新于2025-09-19 17:15:36
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Visible light-induced free radical promoted cationic polymerization using organotellurium compounds
摘要： Organotellurium-mediated polymerization of cyclohexene oxide (CHO), isobutyl vinyl ether (IBVE) and N-vinylcarbazole (NVC) in the presence of diphenyliodonium hexafluorophosphate (DPI) was accomplished under visible light and sunlight. The chain-transfer agent (CTA) ethyl 2-methyl-2-methyltellanylpropionate (EMPTeMe) and poly(methyl methacrylate) with an organotellurium group at the chain end (PMMATeMe) were used as photoinitiators.
关键词： organotellurium compounds,free radical promoted cationic polymerization,photoinitiators,iodonium salt,visible light
更新于2025-09-19 17:15:36
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Modeling the Optimal Conditions for Improved Efficacy and Crosslink Depth of Photo-Initiated Polymerization
摘要： Optimal conditions for maximum ef?cacy of photoinitiated polymerization are theoretically presented. Analytic formulas are shown for the crosslink time, crosslink depth, and ef?cacy function. The roles of photoinitiator (PI) concentration, diffusion depth, and light intensity on the polymerization spatial and temporal pro?les are presented for both uniform and non-uniform cases. For the type I mechanism, higher intensity may accelerate the polymer action process, but it suffers a lower steady-state ef?cacy. This may be overcome by a controlled re-supply of PI concentration during the light exposure. In challenging the conventional Beer–Lambert law (BLL), a generalized, time-dependent BLL (a Lin-law) is derived. This study, for the ?rst time, presents analytic formulas for curing depth and crosslink time without the assumption of thin-?lm or spatial average. Various optimal conditions are developed for maximum ef?cacy based on a numerically-?t A-factor. Experimental data are analyzed for the role of PI concentration and light intensity on the gelation (crosslink) time and ef?cacy.
关键词： optimal ef?cacy,crosslinking,polymerization modeling,photoinitiator,kinetic
更新于2025-09-19 17:15:36
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Ultrafast fabrication of fluorescent organic nanoparticles with aggregation-induced emission feature through the microwave-assisted Biginelli reaction
摘要： Because of its unique optical properties, the aggregation-induced emission (AIE) dye has attracted extensive attention for various applications. Especially, the utilization of AIE-active dyes for fabrication of fluorescent organic nanoparticles (FONs) has attracted the most research interest for biomedical applications. Therefore, the development of novel and effective strategies to design and prepare AIE-active FONs should be of great importance for the biomedical applications of AIE-active FONs. In this report, we reported an ultrafast strategy that based on the one-pot microwave-assisted Biginelli reaction for fabrication of AIE-active poly(AA-AEMA-TPE) copolymers, which use the 2-(methacryloyoxy) ethylacet, acrylic acid (AA) and 4',4'''-(1,2-diphenylethene-1,2-diyl) bis([1,1'-biphenyl]-4-carbaldehyde) (TPE-CHO) as the substrates. The microwave-assisted Biginelli reaction is simple, efficient and atom-economical and can be accomplished within 3 min. Owing to their amphiphilicity, poly(AA-AEMA-TPE) copolymers will self-assemble into FONs with small size and high water dispersibility. The proton nuclear magnetic resonance (1H NMR) spectroscopy, UV-Vis spectrum and fluorescence spectrometer were used to characterize the resultant copolymers. We demonstrated that poly(AA-AEMA-TPE) FONs possess many excellent properties, such as high water dispersibility, intense fluorescence, obvious AIE feature and favorable biocompatibility. The above results suggest that poly(AA-AEMA-TPE) FONs are of great potential for fluorescent imaging. Moreover, the microwave-assisted Biginelli reaction can occur under a rather benign environment with high efficiency and good substrate adaptability. Therefore, we believe that the method developed in this work could greatly advance the applications of AIE-active functional materials.
关键词： microwave-assisted Biginelli reaction,biological imaging,fluorescent polymer nanoparticles,Aggregation-induced emission,living controlled polymerization
更新于2025-09-19 17:15:36
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Synthesis, characterization and nanoaggregates of alkyl and triethylene glycol substituted 3,6-carbazolevinylenes homopolymers and block copolymers
摘要： Ring strained carbazolephanedienes containing octyl and triethylene glycol chains have been prepared by the McMurry coupling reaction of their corresponding dialdehydes. A series of well-defined carbazolevinylene homopolymers and block polymers containing octyl and triethylene glycol chains have been synthesized through ring-opening metathesis polymerization of the corresponding carbazolephanedienes using the third generation Grubbs initiator. The optical and electrochemical properties and morphologies of the homopolymers and block copolymers with different block ratios such as 1:1, 3:1 and 1:3 have been investigated. The bandgap of the polymers is relatively low (2.64–2.79 eV) and is strongly dependent on the side chains. The carbazolevinylene block copolymers with higher composition of the triethylene glycol substituted carbazolevinylene block showed sphere-like nanoaggregates due to the highly disorder and flexibility of the triethylene glycol chains. This work demonstrated well control of the polymer microstructures with specific nanoaggregates in solid state.
关键词： Sphere-like nanoaggregates,Carbazolephanedienes,Polymer microstructures,Ring-opening metathesis polymerization,Carbazolevinylene polymers
更新于2025-09-19 17:15:36
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Core–shell structured poly(vinylidene fluoride)- <i>grafted</i> -BaTiO <sub/>3</sub> nanocomposites prepared <i>via</i> reversible addition–fragmentation chain transfer (RAFT) polymerization of VDF for high energy storage capacitors
摘要： Core–shell structured poly(vinylidene fluoride)-grafted-barium titanate (PVDF-g-BaTiO3) nanocomposites were prepared by surface-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization of VDF from the surface of functionalized BaTiO3 nanoparticles. The ceramic fillers were first surface-modified with xanthate functions to further allow the RAFT grafting of VDF. A series of structured core shells were synthesized by tuning the feed [initiator functionalized nanoparticles]0 : [monomer]0 ratio, varying from 3 to 5, 10 and 20 wt%. Fourier transform infrared spectroscopy (FTIR), high resolution magic angle spinning (HRMAS) NMR and thermogravimetric analysis (TGA) confirmed the successful surface functionalization of the ceramic filler and the grafting of the PVDF shell onto the surface of the BaTiO3 cores. Transmission electron microscopy results revealed that BaTiO3 nanoparticles are covered by thin shells of PVDF, with thickness varying from 2.2 to 5.1 nm, forming a core–shell structure. HRMAS 19F indicated a grafting of 39–50 units of VDF. X-ray diffraction measurements together with FTIR measurements revealed that PVDF was present in the α form. Thermal properties also indicated that the addition of a small amount of the BaTiO3 filler to the PVDF matrix increased the melting temperature from 168 °C for neat PVDF to 173 °C for PVDF-g-BaTiO3 (20 wt%) and decreased the crystallinity of PVDF from 47% to 21%.
关键词： Nanocomposites,Core-Shell Structure,BaTiO3,PVDF,RAFT Polymerization,Polymer Chemistry,Dielectric Materials
更新于2025-09-19 17:15:36
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Thiol–ene click reaction-induced fluorescence enhancement by altering the radiative rate for assaying butyrylcholinesterase activity
摘要： Bis‐ligated, homoleptic magnesium complexes 1–3 were synthesized through the reaction of 1 equiv. dibutyl magnesium with 2 equiv. β‐ketiminato ligands bearing different substituents on the nitrogen atom and 8 position on benzocyclohexanone. All of the complexes were identified by nuclear magnetic resonance (NMR) and X‐ray crystallography. Complexes 2 and 3 adopted distorted tetrahedral geometry around Mg, by chelating of two ancillary ligands, while complex 1 adopted a dimeric structure with penta‐coordination around Mg. These complexes can be used as efficient catalysts for ring‐opening polymerization of L‐lactide, ε‐caprolactone, δ‐valerolactone (δ‐VL) and trimethylene carbonate in the presence of alcohol as a co‐initiator. With the increasing steric bulk of the ancillary ligands, the catalytic activity of Mg complexes was improved significantly. Particularly, complex 3 having the largest steric hindrance showed excellent catalytic performance for the polymerization of δ‐VL. It could polymerize 800 equiv. δ‐VL in 10 min, and produce polyvalerolactone with narrow molecular weight distributions (Mw/Mn < 1.2) at 35°C or higher temperature. No transesterification side reaction was observed. Moreover, complex 3 exhibited good tolerance to excessive alcohol and an immortal polymerization characteristic. The mechanism studies by in situ NMR demonstrated a coordination‐insertion process. Besides, it revealed that the steric bulky substituents in the active species derived from the complex and alcohol prevented the metal center from deactivation.
关键词： ring‐opening polymerization,magnesium complex,polyester,δ‐valerolactone,bis‐ligated
更新于2025-09-19 17:15:36
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Photocatalyzed thiol-alkene coupling: Mechanistic study and polymer synthesis
摘要： Due to the “click” chemistry characteristics of the thiol–ene reaction, these transformations have been gaining an increasing amount of attention in current chemical research. The high efficiency and selectivity of these transformations have been useful for many areas of study, from small molecule organic synthesis, to polymer synthesis and functionalization, to bioconjugation reactions. In this work, a study of a novel method of photochemical thiol–ene reactions using alkyl halides and an tris [2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3) photocatalyst is investigated. This process is shown to progress rapidly and has the benefit of low catalyst and initiator concentrations relative to reagents as well as mild conditions associated with photochemical processes. To understand the mechanism of this process, catalyst and initiator concentrations and other reaction conditions are varied. To demonstrate the utility of this process, a step-growth thiol–ene polymer is synthesized using dithiol and diene monomers and a crosslinked polymer network is synthesized as well.
关键词： thiol–ene,radical reactions,step-growth polymerization,polymer network,photochemistry
更新于2025-09-19 17:15:36