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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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Preparation of a star-shaped copolymer with porphyrin core and four PNIPAM-b-POEGMA arms for photodynamic therapy
摘要： A series of thermosensitive star-shaped copolymers THPP-(PNIPAM-b-POEGMA)4 with 5, 10, 15,20-tetrakis-(4-hydroxyphenyl)-21H,23H-porphyrin (THPP) core and four poly(N-isopropylacrylamide)-b-poly(oligo(ethylene glycol) mono methyl ether methacrylate) (PNIPAM-b-POEGMA) arms were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The low critical solution temperatures (LCSTs) of THPP-(PNIPAM-b-POEGMA)4 with different molecular weights were 37.5 °C, 39.9 °C and 41.9 °C respectively, which depending on the hydrophilic POEGMA contents of copolymers. The micellar structures of copolymers could be formed above the LCSTs. The MTT study indicated that THPP-(PNIPAM-b-POEGMA)4 and THPP showed no significant cytotoxicity toward HeLa cells and L929 cells. And THPP-(PNIPAM-b-POEGMA)4 under light irradiation showed photodynamic activity which photo-toxicity toward HeLa cells was stronger than THPP.
关键词： Porphyrin,Thermosensitivity,Reversible addition-fragmentation chain transfer (RAFT),THPP-(PNIPAM-b-POEGMA)4,Photodynamic therapy
更新于2025-09-23 15:22:29
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A Self-Reporting Photocatalyst for Online Fluorescence Monitoring of High Throughput RAFT Polymerization
摘要： Translating controlled/living radical polymerization (CLRP) from batch to the high throughput production of polymer libraries presents several challenges in terms of both polymer synthesis and characterization. Although recently there have been significant advances in the field of low volume, high throughput CLRP, techniques able to simultaneously monitor multiple polymerizations in an 'online' manner have not yet been developed. Here, we report our discovery that 5,10,15,20-tetraphenyl-21H,23H-porphine zinc (ZnTPP) is a self-reporting photocatalyst that can mediate PET-RAFT polymerization as well as report on monomer conversion via changes in its fluorescence properties. This enables the use of a microplate reader to conduct high throughput 'online' monitoring of PET-RAFT polymerizations performed directly in 384-well, low volume microtiter plates.
关键词： photochemistry,polymerization,online monitoring,PET-RAFT
更新于2025-09-23 15:22:29
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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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Peripheral RAFT polymerization on covalent organic polymer with enhanced aqueous compatibility for controlled generation of singlet oxygen
摘要： The efficient generation of singlet oxygen has attracted a great deal of interest in various fields such as medicine, synthetic chemistry and materials science. In this study, a covalent organic polymer (COP) is prepared by crosslinking the photosensitizer 4,4',4'',4'''-(porphyrin-5,10,15,20-tetrayl)tetraaniline (TAPP) with 4,4'-(anthracene-9,10-diyl)dibenzoic acid (ADDA) via the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/4-dimethylaminopyridine (DMAP) coupling method. The COP is further modified with a hydrophilic polymer i.e. poly(poly(ethylene glycol) methyl ether methacrylate) through grafting-from reversible addition–fragmentation chain transfer (RAFT) polymerization to enhance its solubility in various solvent systems. The modified COP can bind with singlet oxygen through the formation of endoperoxide by ADDA upon the exposure to the red light irradiation. The singlet oxygen incorporated in COP can be then released via the photodynamic mechanism or the cycloreversion by endoperoxide when heated at 110 ℃. Our results have opened new possibilities for simultaneous generation of singlet oxygen by the dual mechanisms, i.e. photodynamic route and singlet oxygen carrier, which demonstrates the promising potential for treating hypoxic tumors.
关键词： RAFT,red LED,photodynamic,grafting from,singlet oxygen,covalent organic polymer,endoperoxides
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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Chemical Synthesis and Characterization of Poly(poly(ethylene glycol) methacrylate)-Grafted CdTe Nanocrystals via RAFT Polymerization for Covalent Immobilization of Adenosine
摘要： This paper describes the functionalization of poly(poly(ethylene glycol) methacrylate) (PPEGMA)-grafted CdTe (PPEGMA-g-CdTe) quantum dots (QDs) via surface-initiated reversible addition–fragmentation chain transfer (SI-RAFT) polymerization for immobilization of adenosine. Initially, the hydroxyl-coated CdTe QDs, synthesized using 2-mercaptoethanol (ME) as a capping agent, were coupled with a RAFT agent, S-benzyl S'-trimethoxysilylpropyltrithiocarbonate (BTPT), through a condensation reaction. Then, 2,2'-azobisisobutyronitrile (AIBN) was used to successfully initiate in situ RAFT polymerization to generate PPEGMA-g-CdTe nanocomposites. Adenosine-above-PPEGMA-grafted CdTe (Ado-i-PPEGMA-g-CdTe) hybrids were formed by the polymer shell, which had successfully undergone bioconjugation and postfunctionalization by adenosine (as a nucleoside). Fourier transform infrared (FT-IR) spectrophotometry, energy-dispersive X-ray (EDX) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy results indicated that a robust covalent bond was created between the organic PPEGMA part, cadmium telluride (CdTe) QDs, and the adenosine conjugate. The optical properties of the PPEGMA-g-CdTe and Ado-i-PPEGMA-g-CdTe hybrids were investigated by photoluminescence (PL) spectroscopy, and the results suggest that they have a great potential for application as optimal materials in biomedicine.
关键词： poly(poly(ethylene glycol methacrylate),CdTe quantum dots,adenosine,SI-RAFT,covalent immobilization
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