Induced Atom Transfer Research Articles

Confining CsPbI3 perovskite in metal organic framework (MOF-545) as stable composite photocatalyst for efficient oxygen-tolerant NIR light-driven atom transfer radical polymerization

Zirconium-porphyrin metal-organic framework (MOF-545) encapsulated all inorganic iodide perovskite (CsPbI3) composite (CsPbI3@MOF-545) is used as highly efficient photocatalyst to catalyze NIR light induced atom transfer radical polymerization (ATRP). The combination of CsPbI3 and MOF-545 leads to a synergistic effect with enhanced photoinduced carrier separation and light absorption performance in the composite photocatalyst. The constructed CsPbI3@MOF-545(10 %) can efficiently catalyze the conversion more than 90 % of various monomers under 810 nm NIR light irradiation. Strong oxygen-resistance has been confirmed in the CsPbI3@MOF-545(10 %) catalyzed photo-ATRP system. In a large-volume photo-ATRP system (100 mL), the polymerization of methyl methacrylate (MMA) achieved a conversion over 90 % in 10 h using NIR light in air. The success of chain extension and block polymerization indicates good end-chain fidelity for the synthesized polymers. The composite photocatalyst still displays high photocatalytic activity for the synthesis of polymers with controllable dispersity after seven photopolymerization cycles, demonstrating its promising potential for practical applications.

Facile fabrication of high thickness hydrophilic polymer brushes via Surface-Initiated Microliter-Scale copper mediated PhotoATRP toward antifouling surfaces

The recent development of sustainable chemistry motivates scientists to develop economically favourable, highly efficient, and environmentally friendly polymerization techniques. This contribution demonstrates a facile fabrication of hydrophilic polymer brushes via surface-initiated photochemically induced atom transfer radical polymerization using a copper catalyst in low concentrations and microlitre volume of polymerization mixture (SI-μL-CuPhotoATRP). The fabrication proceeds by sandwiching of μL reaction solution between a Si-wafer modified with ATRP-initiator and a glass slide under atmospheric and ambient conditions. Optimization of reaction conditions was realized on hydrophilic monomer such as 2-hydroxyethyl methacrylate (HEMA). Effect of various experimental parameters such as light intensity, solvents, ligands, the volume of the reaction solution, size of the Si-wafers, amount of CuBr2, and CuBr2/ligand ratio in kinetics, linear increase of polymer layer thickness, final thickness and profile of unmodified edges were investigated. The successful fabrication of hydrophilic polymer brushes is confirmed via Fourier transfer infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), profilometry and water contact angle. A linear thickness increase with time up to at least 300 nm was achieved, compared to polymethacrylate layers with thickness up to approximately 100 nm previously published by using photoATRP. The general applicability of the optimized conditions for SI-μL-CuPhotoATRP was further proved for two additional hydrophilic monomers, such as glycidyl methacrylate and 2-hydroxypropyl methacrylate. Furthermore, sequential homo and block copolymerization demonstrated the living character of fabrication conditions, permitting facile fabrication of well-controlled tetra block homo/copolymer brushes with a pyramid-like pattern on Si-wafer. Poly(2-hydroxyethyl methacrylate) (PHEMA) brushes-grown surfaces exhibit excellent antifouling properties and long-term structural stability. The facile, affordable, and environmentally friendly SI-μL-CuPhotoATRPapproachprovides avenues for various surface modifications, such as biomedical, soft robotic, and coating applications.

Investigation of Polymer Networks for Dental Fillings Formed by Photochemically Induced Atom Transfer Radical Polymerization of Bifunctional Methacrylates

Investigation of Polymer Networks for Dental Fillings Formed by Photochemically Induced Atom Transfer Radical Polymerization of Bifunctional Methacrylates

Ultrasensitive electrochemical detection of phospholipase C via dual signal amplification based on MVL ATRP and silver nanoparticles

An ultrasensitive electrochemical sensor for phospholipase C (PLC) was developed via dual signal amplification based on metal-free visible-light induced atom transfer radical polymerization (MVL ATRP) and Ag nanoparticles (AgNPs). The environment-friendly MVL ATRP method was used to form aldehyde based polymers on the electrode surface, providing more reaction sites for further silver mirror reaction. In addition, a large number of electrically active AgNPs were obtained through efficient and low-cost silver mirror reaction, which improved the detection signal. Under the optimal conditions, the proposed sensor showed a linear response from 1 mU/L to 106 mU/L for PLC with a detection limit of 0.1032 mU/L (S/N = 3). Most importantly, the sensor was successfully applied to detect PLC in non-tumor cells (MCF-10A) and tumor cells (MCF-7, MDA-MB-231). The obtained values had no obvious difference with that determined by commercial ELISA kit. When 0.5–10 U/L standard PLC were added into the above cells extracts, the recovery rate was between 96.1% and 102.9%, and the RSD was less than 4.02%. The results showed that the fabricated PLC sensor had acceptable potential in clinical applications.

Flame-retardant finishing of cotton fabric by surface-initiated photochemically induced atom transfer radical polymerization

Flame-retardant finishing of cotton fabric by surface-initiated photochemically induced atom transfer radical polymerization

Mechanically induced atom transfer radical polymerization with high efficiency via piezoelectric heterostructures

A facile ultrasonication induced atom transfer radical polymerization (ATRP) mediated via piezoelectric heterostructure was developed. ZnO/BaTiO 3 heterostructure was prepared by in-situ deposition of zinc precursor on BaTiO 3 particles followed by high temperature annealing. Under ultrasonic activation, as-synthesized piezoelectric ZnO/BaTiO 3 heterostructure with an elevated macroscopic polarization could facilitate piezoelectric induced electron-hole pairs with more efficient separation and transfer, leading to the enhanced piezocatalytic in controlled living polymerization. High efficiency of ultrasonication mediated ATRP of methyl methacrylate (MMA) by ZnO/BaTiO 3 heterostructure about 63.1% conversion was achieved under 4 h ultrasonic agitation, providing PMMA homopolymer with well-defined molecular weight, narrow molecular dispersity and high end-group fidelity. Furthermore, implications of CuBr 2 /TPMA concentrations, piezoelectric materials, ZnO/BaTiO 3 heterostructure loading and distinct monomer were systematically investigated. Process of ultrasonication-mediated ATRP could be readily controlled by ultrasound switch on/off. The versatility of ultrasonication-mediated ATRP system was further verified by the preparation of star-like polymer. The ability of transfer piezoelectric-induced electrons from ZnO/BaTiO 3 heterostructure to CuBr 2 /TPMA and nature of ZnO/BaTiO 3 heterostructure were investigated to reveal the mechanism of ultrasonication mediated ATRP. A facile and robust atom transfer radical polymerization catalyzed by piezocatalyst with high efficiency was developed in this study. • Piezoelectric catalyst enabled mechanically induced atom transfer radical polymerization with high efficiency.

Simple Full-Spectrum Heterogeneous Photocatalyst for Photo-induced Atom Transfer Radical Polymerization (ATRP) under UV/vis/NIR and its Application for the Preparation of Dual Mode Curing Injectable Photoluminescence Hydrogel.

The utilizing light with broadband range has attracted lots of research interest for the photo induced reversible-deactivation radical polymerization (RDRP). However, it is still a challenge for a single catalyst to simultaneously respond to various lights with highly varied wavelengths. Here, we proposed a simple strategy for the preparation of a heterogeneous photocatalyst suitable for photo induced atom transfer radical polymerization (photoATRP) under full spectrum (from UV/vis light to NIR), by combining pyridine nitrogen doped carbon dots (N-CDs) and upconversion nanoparticles (UCNPs). In the presence of these robust UCNP@SiO2@N-CDs composite particles, the photoATRP could be carried on under the different irradiations of UV, blue, green, red, white, and 980 nm NIR light, with a low loading of part per million concentrations of the CuBr2/L catalyst. Moreover, the excellent solvent and aqueous compatibility allow UCNP@SiO2@N-CDs to be capable for photoATRP in both organic solvents and aqueous media, providing well-defined hydrophobic and hydrophilic polymers with low dispersity and excellent chain-end fidelity. In addition, the photoATRP with 980 nm NIR exhibited excellent penetrations through visible-light-proof barriers. The system could be used for the preparation of an injectable hydrogel that had dual curing and photoluminescence modes. Owing to the "living" characteristics of polymer chains achieved through ATRP, the hydrogel was capable to be easily repaired by using monomer as the binder.

Wavelength-Resolved PhotoATRP.

The careful mapping of photoinduced reversible-deactivation radical polymerizations (RDRP) is a prerequisite for their applications in soft matter materials design. Here, we probe the wavelength-dependent behavior of photochemically induced atom transfer radical polymerization (ATRP) using nanosecond pulsed-laser polymerization (PLP). The photochemical reactivities at identical photon fluxes of methyl acrylate in terms of conversion, number-average molecular weight, and dispersity of the resulting polymers are mapped against the absorption spectrum of the copper(II) catalyst in the range of 305-550 nm. We observe a red shift of the action spectrum relative to the absorption spectrum of the copper(II) catalyst. Both the number-average molecular weight and the dispersity show a wavelength dependence, while the molecular weight and conversion remain linearly correlated. The reported data allow the judicious selection of optimum wavelengths for photoATRP.

Antibacterial cotton fabric prepared by surface-initiated photochemically induced atom transfer radical polymerization of 2-(dimethylamino)ethyl methacrylate with subsequent quaternization

Antibacterial highly grafted cotton fabric with good laundry resistance was prepared using photoATRP in the presence of air.

Facile fabrication of water-soluble polyacrylic acid encapsulated core@shell upconversion nanoparticles via metal-free light induced surface initiated atom transfer radical polymerization

Upconversion nanoparticles (UCNP) have great potential for applications in biological fields due to their unique anti-stokes luminescent properties. However, the successful preparation of water-soluble upconversion nanoparticles with well-controlled morphology still remains a great challenge. Herein, a facile fabrication method for the preparation of water-soluble polyacrylic acid (PAA) encapsulated core@shell upconversion nanoparticles through metal-free light induced surface initiated atom transfer radical polymerization (LI-SI-ATRP) was presented. This method involves the modification of oleate acid capped upconversion nanoparticles by bi-functional ligands with ATRP initiating sites. Then the water-soluble polyacrylic acid modified core@shell upconversion nanoparticles were synthesized by metal-free light induced atom transfer radical polymerization. The nanoparticles prepared can be well dispersed in water and emit strong green light when excited by 980 nm near-infrared laser which suggesting that these PAA modified UCNP are promising candidates for luminescent bioimaging.

Intramolecular photoinitiator induced atom transfer radical polymerization for electrochemical DNA detection.

A novel electrochemical biosensor was reported for the first time to achieve highly sensitive DNA detection based on photoinduced atom transfer radical polymerization (photoATRP). In this work, PNA was applied as the capture probe to specifically recognize the target DNA (TDNA), and we utilized lung cancer DNA as TDNA. The ATRP initiator was introduced to the electrode surface via phosphate-Zr4+-carboxylate chemistry. PhotoATRP was activated under blue light irradiation based on a photoinitiator I2959, which produced free radicals via homolytic cleavage. Subsequently, Cu2+ was reduced to Cu+ with the assistance of the free radicals, and numerous electroactive probes were grafted onto the electrode surface. Under optimal conditions, the limit of detection (LOD) of this method was 3.16 fM (S/N = 3, R2 = 0.992), and the linear range was from 10 fM to 1.0 nM. More importantly, the preparation process of this biosensor was simple and less laborious with a low background signal, suggesting good potential in practical applications.

Oxygen‐Tolerant Photochemically Induced Atom Transfer Radical Polymerization of the Renewable Monomer Tulipalin A

AbstractWell defined homopolymers and block copolymers from renewable monomer α‐methylene‐γ‐butyrolactone (MBL) were prepared using photochemically induced atom transfer radical polymerization (photoATRP) in the presence of only 50–200 ppm of copper catalyst without the requirement of air removal from the polymerization mixture. The effect of solvent type and volume, ligand‐to‐copper ratio, catalyst concentration, ligand type, and the possible partial replacement of an expensive ligand with cheap simple amines, were investigated. The livingness of the oxygen‐tolerant photoATRP system was investigated by chain extension polymerization and the possibility to prepare block copolymers by chain extension of PMBL‐Br macroinitiator with methyl methacrylate (MMA) as well as by chain extension of PMMA‐Br macroinitiator with PMBL block was studied. It was shown that a concentration of catalyst as low as 50 ppm is sufficient to provide good control over the molecular characteristics and kinetics.

Simple tertiary amines as promotors in oxygen tolerant photochemically induced ATRP of acrylates

Well-defined poly(methyl acrylate) (PMA) and poly(n-butyl acrylate) (PBA) are prepared via photochemically induced atom transfer radical polymerization (photoATRP) using ppm amounts of CuBr2/tris[2-(dimethylamino)ethyl]amine (Me6TREN) catalyst complex without degassing of the polymerization mixture. The effect of light intensity and partial replacement of the excess of expensive Me6TREN ligand with cheaper tertiary amines on kinetics of the polymerization was investigated in various solvents. The addition of triethylamine to photoATRP system resulted in both significant shortening the induction period and increasing the polymerization rate. High livingness of the oxygen tolerant photoATRP system containing triethylamine was proved by chain-extension polymerizations resulting in formation of PMA-b-PBA copolymer. The presented photoATRP system can have tremendous importance from an industrial point of view since the well-defined polyacrylates can be prepared almost without any induction period and in short polymerization time without necessity of both air removal and using the excess of expensive ligand.

Preparation of erythromycin imprinted polymer by metal-free visible-light–induced ATRP and its application in sensor

Erythromycin (ERY) molecular imprinted polymer was prepared on the surface of Au electrode modified with Ni and Au nanoclusters (MIP/AuNCs/Ni/Au) via metal-free visible-light–induced atom transfer radical polymerization, which was very easy, controllable, and environmentally benign. MIP/AuNCs/Ni/Au was examined by energy dispersive spectrometer (EDS), scanning electron microscope (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Further, MIP/AuNCs/Ni/Au was successfully used for the determination of ERY by differential pulse voltammetry (DPV). Under the optimal conditions, MIP/AuNCs/Ni/Au gave a linear correlation over the ERY concentration from 1.0 × 10−8 to 1.0 × 10−1 mg/L with the detection limit of 3.2 × 10−9 mg/L (S/N = 3). Comparing with the similar sensors, the larger linear range and lower detection limit indicated the promising prospect of this electrochemical sensor. Hence, this study was of great importance for the polymer-modified electrodes and the sensitive detection of ERY.

Preparation and controlled drug delivery applications of mesoporous silica polymer nanocomposites through the visible light induced surface-initiated ATRP

The mesoporous materials with large pore size, high specific surface area and high thermal stability have been widely utilized in a variety of fields ranging from environmental remediation to separation and biomedicine. However, surface modification of these silica nanomaterials is required to endow novel properties and achieve better performance for most of these applications. In this work, a new method has been established for surface modification of mesoporous silica nanoparticles (MSNs) that relied on the visible light induced atom transfer radical polymerization (ATRP). In the procedure, the copolymers composited with itaconic acid (IA) and poly(ethylene glycol)methyl acrylate (PEGMA) were grafted from MSNs using IA and PEGMA as the monomers and 10-Phenylphenothiazine(PTH) as the organic catalyst. The successful preparation of final polymer nanocomposites (named as MSNs-NH2-poly(IA-co-PEGMA)) were evidenced by a series of characterization techniques. More importantly, the anticancer agent cisplatin can be effectively loaded on MSNs-NH2-poly(IA-co-PEGMA) and controlled release it from the drug-loading composites with pH responsive behavior. As compared with conventional ATRP, the light induced surface-initiated ATRP could also be utilized for preparation of various silica polymer nanocomposites under rather benign conditions (e.g. absent of transition metal ions, low polymerization temperature and short polymerization time). Taken together, we have developed a rather promising strategy method for fabrication of multifunctional MSNs-NH2-poly(IA-co-PEGMA) with great potential for biomedical applications.

Photochemically Induced ATRP of (Meth)Acrylates in the Presence of Air: The Effect of Light Intensity, Ligand, and Oxygen Concentration.

Well-defined poly(methyl methacrylate) (PMMA) and poly(methyl acrylate) (PMA) are prepared via photochemically induced atom transfer radical polymerization (photoATRP) using ppm amounts of CuBr2 /tris(2-pyridylmethyl)amine and CuBr2 /tris[2-(dimethylamino)ethyl]amine catalyst complexes, respectively, without degassing of polymerization mixture and with no need to introduce an external reducing agent to the system. The effect of ligand to CuBr2 ratio on kinetic and induction period during the polymerization of MMA and MA is investigated. The induction period is influenced also by the amount of oxygen in the polymerization system. Both the kinetics of MA polymerization and the induction period are affected by light intensity. Finally, the high livingness and initiation efficiency of the photoATRP system in the presence of air are proved by chain extension polymerizations. The presented system is valuable from an industrial point of view, since after optimization, well-defined and high-molar-mass poly(meth)acrylates can be prepared without the necessity of degassing the system, while the polymerization can be proceeded quickly and without an induction period.

Spatial control over brush growth through sunlight-induced atom transfer radical polymerization using dye-sensitized TiO2 as a photocatalyst.

Simulated-sunlight induced atom transfer radical polymerization is used for spatial control over polymer brush growth by in situ photo-generation of the Cu(I) /L activator complex from its higher oxidation state Cu(II) /L deactivator complex using dye sensitized titanium dioxide nano-particles. The polymerization is well controlled under sunlight irradiation. Another attractive feature of this method is the possibility of creating various patterned surfaces of brushes using photomasks. When a nanoporous alumina oxide membrane is used as the template for confinement diffusion of photogenerated Cu(I) /L catalyst, patterns with sub-50 nm resolution are obtained.

PH-sensitive membranes prepared with poly(methyl methacrylate) grafted poly(vinylidene fluoride) via ultraviolet irradiation-induced atom transfer radical polymerization

Ultraviolet (UV) irradiation induced atom transfer radical polymerization (ATRP) was performed to graft poly(methyl methacrylate) (PMMA) onto poly(vinylidene fluoride) (PVDF) and obtain copolymer (PVDF-g-PMMA).

Sunlight induced atom transfer radical polymerization by using dimanganese decacarbonyl

A new photoredox catalyst system for atom transfer radical polymerization is developed on the basis of visible light photocatalysis using dimanganese decacarbonyl (Mn2(CO)10) that initiates and controls the polymerization at ambient temperature. The polymerization was performed by a Mn2(CO)10–alkyl halide system with visible- or sunlight in the presence of parts per million (ppm) copper catalysts. The photogenerated ˙Mn(CO)5 radicals are not only able to abstract halogen atoms from alkyl halides to generate carbon centered radicals but also reduce the CuIIBr2 to CuIBr directly, which was used as an activator in the Atom Transfer Radical Polymerization (ATRP) of vinyl monomers such as methyl methacrylate, methyl acrylate and styrene. The method was also used to synthesize graft copolymers from commercially available poly(vinyl chloride) without additional modification.