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Controlling Chain Coupling and Single Chain Ligation by Two Colours of Visible Light
摘要： While photochemical synthesis offers access to spatiotemporal reaction control, its potential to selectively address specific reactions by the colour of light is usually limited by ubiquitous spectral absorption overlaps of the reactive groups. Inhere, a new concept is introduced that actively suppresses one ligation reaction by triggering the cycloreversion of the [2+2] cycloaddition of styrylpyrene. Combination of the photoreversible styrylpyrene chemistry with the [4+4] cycloaddition of 9-triazolylanthracene allows to initially induce chain coupling using UV light and to subsequently ligate the formed single chain nanoparticle (SCNP) with a second polymer chain using blue light. Seizing upon the first sequence independent λ-orthogonal reactivity established in here, the same macromolecular architecture was obtained in reverse irradiation sequence, by blue and subsequent violet light irradiation – completely foregoing high energy UV-light.
关键词： Polymer Ligation,Orthogonal Reactions,RAFT polymerization,Photochemistry,Single Chain Nanoparticles
更新于2025-09-23 15:23:52
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Exploiting Wavelength Orthogonality for Successive Photoinduced Polymerization-Induced Self-Assembly and Photo-Crosslinking
摘要： We report a facile benchtop process for the synthesis of cross-linked polymeric nanoparticles by exploiting wavelength-selective photochemistry to perform orthogonal photoinduced polymerization-induced self-assembly (Photo-PISA) and photo-crosslinking processes. We first established that the water-soluble photocatalyst, zinc meso-tetra(N-methyl-4-pyridyl) porphine tetrachloride (ZnTMPyP) could activate the aqueous PET-RAFT dispersion polymerization of hydroxypropyl methacrylate (HPMA). This photo-PISA process could be conducted under low energy red light (λ max = 595 nm, 10.2 mW/cm2) and without deoxygenation due to the action of the singlet oxygen quencher, biotin (vitamin B7), which allowed for the synthesis of a range of nanoparticle morphologies (spheres, worms, and vesicles) directly in 96-well plates. To perform wavelength selective nanoparticle cross-linking, we added the photoresponsive monomer, 7-[4-(trifluoromethyl)coumarin] methacrylamide (TCMAm) as a comonomer without inhibiting the evolution of the nanoparticle morphology. Importantly, under red light, exclusive activation of the photo-PISA process occurs, with no evidence of TCMAm dimerization under these conditions. Subsequent switching to a UV source (λ max = 365 nm, 10.2 mW/cm2) resulted in rapid cross-linking of the polymer chains, allowing for retention of the nanoparticle morphology in organic solvents. This facile synthesis of cross-linked spheres, worms, and vesicles demonstrates the utility of orthogonal light-mediated chemistry for performing decoupled wavelength selective chemical processes.
关键词： photoinduced polymerization-induced self-assembly,wavelength orthogonality,polymeric nanoparticles,photo-crosslinking,PET-RAFT polymerization
更新于2025-09-23 15:21:01
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Photo-controlled RAFT polymerization mediated by organic/inorganic hybrid photoredox catalysts: enhanced catalytic efficiency
摘要： Photo-controlled RAFT polymerization mediated by organic/inorganic hybrid photoredox catalysts: enhanced catalytic efficiency. Metalloporphyrins (MTPPs) play an important role in the conversion of light energy to initiate photo-induced electron transfer–reversible addition–fragmentation chain transfer (PET-RAFT) polymerization, in which zinc tetraphenylporphyrin (ZnTPP) has attracted a high degree of attention. However, the self-aggregation effect of porphyrins in some organic solvents such as dimethyl sulphoxide (DMSO) leads to quenching of the excited state of the MTPPs and reduces their photocatalytic capacity in a concentration-dependent manner. In this study, a ZnTPP–POSS organic/inorganic complex was fabricated by linking a polyhedral oligomeric silsesquioxane (POSS) to ZnTPP. The aggregation of the photocatalyst was efficiently depressed in a PET-RAFT polymerization which was catalyzed by ZnTPP–POSS under green light (λmax = 515 nm, 3 mW cm?2). Compared to ZnTPP, the reactions using ZnTPP–POSS as the photocatalyst were well controlled for different monomers with accelerated reaction rates. Well-defined block copolymers were successfully achieved by the chain-extension reaction which demonstrates the high-end fidelities of this polymerization approach.
关键词： Photo-controlled RAFT polymerization,PET-RAFT polymerization,organic/inorganic hybrid photoredox catalysts,block copolymers,ZnTPP–POSS
更新于2025-09-23 15:19:57
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Xanthene Dye-Functionalized Conjugated Porous Polymers as Robust and Reusable Photocatalysts for Controlled Radical Polymerization
摘要： Photoinduced electron/energy transfer?reversible addition?fragmentation chain transfer (PET?RAFT) polymerization represents a versatile and highly e?cient method for polymerizations of wide-ranging monomer variances upon solar energy harvesting. Although signi?cant progress has been achieved, several drawbacks are still associated with existing photocatalysts, such as toxicity of transition metals, high cost, poor stability, and unavoidable puri?cation procedures because of the photobleaching e?ect, to name a few. Herein, 1,4-diethynylbenzene-linked xanthene dye-conjugated porous polymers (CPPs) have been established as potential heterogenous photocatalysts of PET?RAFT polymerization. With this two-dimensional planar architecture, we demonstrate dual-stimuli toggling of RAFT polymerization using two di?erent external physical manipulations: light “ON”/“OFF” and solution pH “LOW”/“HIGH”. In addition, these CPPs endowed radical polymerizations with various impressive features such as compatibility of diverse monomer formulations, unique oxygen tolerance, and ppm-level catalyst dosage. Demonstrations of chain extension and catalyst recycling further highlight the robustness and performance of this CPP catalyst. Through the study of structure?property relationship using the experimental analyses, we envisage that a series of xanthene dye-functionalized CPPs can be developed as visible light-absorbing organocatalysts rivaling transition-metal photocatalysts.
关键词： PET?RAFT polymerization,visible light-absorbing organocatalysts,xanthene dye-functionalized conjugated porous polymers,dual-stimuli toggling,heterogeneous photocatalysts
更新于2025-09-23 15:19:57
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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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Surface grafting of fluorescent polymers on halloysite nanotubes through metal-free light-induced controlled polymerization: Preparation, characterization and biological imaging
摘要： Halloysite nanotubes (HNTs) are a kind of aluminosilicate clay with a unique hollow tubular structure that has been intensively explored for various applications especially in biomedical fields owing to their excellent biocompatibility, biodegrading potential and low cost. Surface modification of HNTs with functional polymers will greatly improve their properties and endow new functions for biomedical applications. In this work, a light-induced reversible addition-fragmentation chain transfer (RAFT) polymerization was introduced to successfully prepare HNTs based fluorescent HNTs/poly(PEGMA-Fl) composites in the presence of oxygen using diacrylate-fluorescein and poly (ethylene glycol) methyl ether methacrylate (PEGMA) as the monomers. Without other catalysts, heating, and deoxygenation procedure, the polymerization process can take place under mild conditions. Besides, owing to the introduction of fluorescein and PEGMA on the surface of HNTs, the resultant HNTs/poly(PEGMA-Fl) composites display high water dispersibility and stable fluorescence. The results from cell viability examination and confocal laser scanning microscopy also demonstrated that HNTs/poly(PEGMA-Fl) composites could be internalized by L929 cells with bright fluorescence and low cytotoxicity. Taken together, we developed a novel photo-initiated RAFT polymerization method for the fabrication of HNTs based fluorescent polymeric composites with great potential for biomedical applications. More importantly, many other multifunctional HNTs based polymer composites could also be fabricated through a similar strategy owing to good designability of RAFT polymerization.
关键词： fluorescent composites,biomedical applications,Halloysite nanotubes,light-induced polymerization,surface-initiated RAFT polymerization
更新于2025-09-19 17:13:59
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A Versatile 3D and 4D Printing System through Photocontrolled RAFT Polymerization
摘要： Reversible addition-fragmentation chain-transfer (RAFT) polymerization is a valuable tool for synthesizing macromolecules with controlled topologies and diverse chemical functionalities. However, the application of RAFT polymerization to additive-manufacturing processes has been prevented due to the slow polymerization rates of typical systems. In this work, we developed a rapid visible light mediated RAFT polymerization process and applied it to a 3D printing system. The photosensitive resins contained a metal-free dye (erythrosin B) in conjunction with a tertiary amine co-catalyst (triethanolamine) and a trithiocarbonate RAFT agent (2-(butylthiocarbonothioylthio) propanoic acid) to afford polymerization without prior deoxygenation. The reaction components are non-toxic, metal free and environmentally friendly (water based photosensitive resin), which tailors these systems toward the fabrication of biomaterials. Following optimization of the resin formulation by varying the ratio of photocatalyst and tertiary amine, a variety of 3D printing conditions were investigated to prepare functional materials using green light (λmax = 525 nm, I0 = 0.32 mW/cm2). Furthermore, the mechanical properties of these 3D printed materials were tested under different conditions. Interestingly, the concentration of trithiocarbonate impacted the mechanical properties and the performance of these materials. Remarkably, the use of a photoinduced polymerization process provided facile spatial control over the network structure by varying the light dose to each layer of the 3D printed material; using this strategy, a 4D printing process was demonstrated via 3D printing and subsequent swelling and dehydration induced actuation. Furthermore, the trithiocarbonate species incorporated in the polymer networks were able to be reactivated after the initial 3D printing process, which enabled post functionalization of the printed materials via secondary photopolymerization processes. This RAFT-mediated 3D and 4D printing process should provide access to a range of new functional and stimuli-responsive materials.
关键词： Functional Materials,Photopolymerization,3D printing,4D printing,RAFT polymerization
更新于2025-09-19 17:13:59
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A Versatile 3D and 4D Printing System through Photocontrolled RAFT Polymerization
摘要： Reversible addition-fragmentation chain-transfer (RAFT) polymerization is a valuable tool for synthesizing macromolecules with controlled topologies and diverse chemical functionalities. However, the application of RAFT polymerization to additive-manufacturing processes has been prevented due to the slow polymerization rates of typical systems. In this work, we developed a rapid visible light mediated RAFT polymerization process and applied it to a 3D printing system. The photosensitive resins contained a metal-free dye (erythrosin B) in conjunction with a tertiary amine co-catalyst (triethanolamine) and a trithiocarbonate RAFT agent (2-(butylthiocarbonothioylthio) propanoic acid) to afford polymerization without prior deoxygenation. The reaction components are non-toxic, metal free and environmentally friendly (water based photosensitive resin), which tailors these systems toward the fabrication of biomaterials. Following optimization of the resin formulation by varying the ratio of photocatalyst and tertiary amine, a variety of 3D printing conditions were investigated to prepare functional materials using green light (λmax = 525 nm, I0 = 0.32 mW/cm2). Furthermore, the mechanical properties of these 3D printed materials were tested under different conditions. Interestingly, the concentration of trithiocarbonate impacted the mechanical properties and the performance of these materials. Remarkably, the use of a photoinduced polymerization process provided facile spatial control over the network structure by varying the light dose to each layer of the 3D printed material; using this strategy, a 4D printing process was demonstrated via 3D printing and subsequent swelling and dehydration induced actuation. Furthermore, the trithiocarbonate species incorporated in the polymer networks were able to be reactivated after the initial 3D printing process, which enabled post functionalization of the printed materials via secondary photopolymerization processes. This RAFT-mediated 3D and 4D printing process should provide access to a range of new functional and stimuli-responsive materials.
关键词： Functional Materials,Photopolymerization,3D printing,4D printing,RAFT polymerization
更新于2025-09-19 17:13:59
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Oxygen Tolerant PET-RAFT Facilitated 3D Printing of Polymeric Materials under Visible LEDs
摘要： Photopolymerization-based 3D printing process is typically conducted using free radical polymerization, which leads to fabrication of immutable materials. An alternative 3D printing of polymeric materials using trithiocarbonate (TTC) reversible addition-fragmentation chain transfer (RAFT) agents has always been a challenge for material and polymer scientists. Herein we report 3D printing of RAFT-based formulations that can be conducted fully open to air using standard digital light processing (DLP) 3D printer and under mild conditions of visible light at blue (λ max = 483 nm, 4.16 mW/cm2) or green (λ max = 532 nm, 0.48 mW/cm2) wavelength. Our approach is based on activation of TTC RAFT agents using eosin Y (EY) as a photoinduced electron-transfer (PET) catalyst in the presence of a reducing agent (triethylamine (TEA)), which facilitated oxygen tolerant 3D printing process via a reductive PET initiation mechanism. Re-activation of the TTCs present within the polymer networks enables post-printing monomer insertion into the outer layers of an already printed dormant object under a second RAFT process, which provides a pathway to design a more complex 3D printing. To our best knowledge, this is the first example of oxygen tolerant EY/TEA catalyzed PET-RAFT facilitated 3D printing of polymeric materials. We believe that our strategy is a significant step forward in the field of 3D printing.
关键词： Oxygen Tolerant,Trithiocarbonate,3D Printing,Visible Light-Induced PET-RAFT Polymerization,Digital Light Processing,Photoinduced Electron-Transfer
更新于2025-09-16 10:30:52
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Semiconductor Quantum Dots Are Efficient and Recyclable Photocatalysts for Aqueous PET-RAFT Polymerization
摘要： This Letter describes the use of CdSe quantum dots (QDs) as photocatalysts for photoinduced electron transfer reversible addition?fragmentation chain transfer (PET-RAFT) polymerization of a series of aqueous acrylamides and acrylates. The high colloidal solubility and photostability of these QDs allowed polymerization to occur with high efficiency (>90% conversion in 2.5 h), low dispersity (PDI < 1.1), and ultralow catalyst loading (<0.5 ppm). The use of protein concentrators enabled the removal of the photocatalyst from the polymer and monomer with tolerable metal contamination (8.41 ug/g). These isolated QDs could be recycled for four separate polymerizations without a significant decrease in efficiency. By changing the pore size of the protein concentrators, the QDs and polymer could be separated from the remaining monomer, allowing for the synthesis of block copolymers using a single batch of QDs with minimal purification steps and demonstrating the fidelity of chain ends.
关键词： block copolymers,CdSe quantum dots,photocatalysts,aqueous acrylamides,acrylates,protein concentrators,PET-RAFT polymerization
更新于2025-09-12 10:27:22