- Flow Photochemistry for Single-Chain Polymer Nanoparticle Synthesis
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Single chain polymer nanoparticles (SCNP) are an attractive polymer architecture that provides functions seen in folded biomacromolecules. The generation of SCNPs, however, is limited by the requirement of a high dilution chemical step, necessitating the use of large reactors to produce processable quantities of material. Herein, the chemical folding of macromolecules into SCNPs is achieved in both batch and flow photochemical processes by the previously described photodimerization of anthracene units in polymethylmethacrylate (100 kDa) under UV irradiation at 366 nm. When employing flow chemistry, the irradiation time is readily controlled by tuning the flow rates, allowing for the precise control over the intramolecular collapse process. The flow system provides a route at least four times more efficient for SCNP formation, reaching higher intramolecular cross-linking ratios five times faster than batch operation.
- Galant, Or,Donmez, Hasan Barca,Barner-Kowollik, Christopher,Diesendruck, Charles E.
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- Complexation and fluorescence behavior of a copolymer bearing azacrown ether and anthracene moieties
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Copolymers bearing azacrown ether and anthracene moieties were synthesized using methacrylates of N-2-ethyl-azacrown ether or 9-hydroxymethylanthracene. Their fluorescence behaviors in the presence of alkali metal ions were measured in THF:H2O = 10:1 solution. Maximum fluorescence intensities for copolymers bearing aza-12-crown-4, 15-crown-5 and 18-crown-6 were observed for with Na+, K+ and K+, respectively. The largest change in fluorescence behavior was observed for the copolymer bearing aza-18-crown-6 in the presence of K+. The magnitude of the increase in the fluorescence intensity was related to the content of the crown ether moiety. The time-dependent changes in the fluorescence spectra using photo-irradiation were also investigated. Crown Copyright
- Sakamoto, Hidefumi,Anase, Tomohiro,Osuga, Hideji,Kimura, Keiichi
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- Controlled radical polymerization of anthracene-containing methacrylate copolymers for stimuli-responsive materials
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Novel reversible networks utilizing photodimerization of crosslinkable anthracene groups and thermal dissociation were investigated. Reversible addition-fragmentation chain transfer polymerization yielded well-defined copolymers with 9-anthrylmethyl methacrylate (AMMA) and other alkyl methacrylates such as methyl methacrylate (MMA) and 2-ethylhexyl methacrylate (EHMA) having different AMMA compositions. Well-controlled block copolymerization of AMMA and alkyl methacrylates was also successfully accomplished using a trithiocarbonate-terminated poly(alkyl methacrylate) macro-chain transfer agent. The anthracene-containing copolymers showed reversibility via crosslinking based on photodimerization with ultraviolet irradiation and subsequent thermal dissociation.
- Yokoe, Makito,Yamauchi, Koji,Long, Timothy E.
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- Single-Chain Folding Nanoparticles as Carbon Nanotube Catchers
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This contribution describes a simple method for preparing polymeric nanoparticles using photodimerization of anthracene moieties on the side chain of terpolymers in dilute regime and transformation of obtained polymeric nanoparticles into pyrene functional nanoparticles via Menschutkin quaternization procedure. Subsequently, pyrene possessing polymeric nanoparticles are attached onto multiwalled carbon nanotube (MWCNT) surfaces by π–π stacking strategy. Gel permeation chromatography, thermal gravimetric analysis, ultraviolet–visible, and fluorescence spectroscopies are used to analyze modified nanoparticles and their precursors. Electron microscopy and dispersion studies show that pyrene-modified polymeric nanoparticles are able to interconnect various CNTs.
- Bilgi, Mesut,Karaca Balta, Demet,Temel, Binnur Aydogan,Temel, Gokhan
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- Photochemical formation of a core-crosslinked micelle using an anthracene-containing amphiphilic copolymer
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In order to develop photoresponsive polymeric micellar systems, an amphiphilic block copolymer consisting of anthracene moieties was successfully prepared by atom transfer radical polymerization. In an aqueous solution, the photodimerization of the anthracene moieties occurred in the micellar core upon irradiation (> 360 nm), keeping the mean diameter constant. The photodimerization caused the interpolymer reaction to form a core-crosslinked micelle.
- Morikawa, Hiroshi,Kotaki, Yasuharu,Mihara, Ryota,Kiraku, Yuki,Ichimura, Shigetoshi,Motokucho, Suguru
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- Triplet-triplet annihilation upconversion from rationally designed polymeric emitters with tunable inter-chromophore distances
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We report an investigation of triplet-triplet annihilation upconversion (TTA-UC) based on polymeric emitters with tunable inter-chromophore distances. Poly[(9-anthrylmethyl methacrylate)-co-(methyl methacrylate)] (poly(AnMMA-co-MMA)) with different percentages of AnMMA was synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization, and used as an emitter in association with platinum octaethylporphyrin as a sensitizer to form TTA-UC systems. It is observed that the TTA-UC intensity first increases with increasing AnMMA percentage in the polymers then decreases, and ultimately disappears, upon further increasing the AnMMA percentage. The results shed light on the key factors affecting TTA-UC in polymers, and have implications for the design of polymer-based TTA-UC systems. This journal is
- Yu, Xinjun,Cao, Xian,Chen, Xiaoping,Ayres, Neil,Zhang, Peng
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- Fluorescent nanostructures from aromatic diblock copolymers via atom transfer radical polymerization
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Well-defined fluorophore (anthracene or pyrene) containing copolymers were synthesized via atom transfer radical polymerization (ATRP) using methyl methacrylate (MMA) and fluorophore bound methacrylate (AntMA or PyMA). The copolymers exhibited clearly distinct thermal and optical properties, in terms of glass transition temperature (Tg) and emission spectrum, depending on the polymer structures. Moreover self-assembly properties of the copolymers affected the formation of the polymer nanostructures at condensed phase, to distinguish the random against block copolymers. The antracene containing random copolymer had a single Tg value while antracene containing block copolymer had two Tg values. In addition, sharp fluorescence peaks (398, 416 and 439 nm) werer observed in the random copolymer of antracene. In contrast, the anthracene containing block copolymer showed a broad tailing of the peak reaching ～550 nm. Interestingly, the copolymers having both randomly distributed anthracene units and consecutively connected pyrene units exhibited sharp emission at 398, 416, and 442 nm originated from the antracene unit and pyrene excimer emission at 482 nm. More importantly, well ordered nanopore films and nano scale micelle structures, originated from the self-assembly of antracene or pyrene block unit, were formed in block copolymers, while any type of an ordered structure was not found from the random copolymers. Therefore fluorescent nanostructures could be well-controlled by the polymers structures containing antracene and pyrene units, which might be widely useful for the development of novel photonics, optoelectronics, and sensor devices.
- You, Jungmok,Kim, Eunkyoung
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- Porphyrin-Cored Polymer Nanoparticles: Macromolecular Models for Heme Iron Coordination
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Porphyrin-cored polymer nanoparticles (PCPNs) were synthesized and characterized to investigate their utility as heme protein models. Created using collapsible heme-centered star polymers containing photodimerizable anthracene units, these systems afford model heme cofactors buried within hydrophobic, macromolecular environments. Spectroscopic interrogations demonstrate that PCPNs display redox and ligand-binding reactivity similar to that of native systems and thus are potential candidates for modeling biological heme iron coordination.
- Rodriguez, Kyle J.,Hanlon, Ashley M.,Lyon, Christopher K.,Cole, Justin P.,Tuten, Bryan T.,Tooley, Christian A.,Berda, Erik B.,Pazicni, Samuel
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supporting information
p. 9493 - 9496
(2016/10/13)
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- Well-defined diblock copolymers possessing fluorescent and metal chelating functionalities as novel macromolecular sensors for amines and metal ions
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The amino- and metal-ion sensing capability of a novel type of well-defined block copolymers based on 9-anthrylmethyl methacrylate (AnMMA; hydrophobic, fluorescent) and 2-(acetoacetoxy)ethyl methacrylate (AEMA; hydrophobic, metal chelating) has been investigated in organic media. AEMAx-b-AnMMA y diblock copolymers were prepared for the first time using reversible addition-fragmentation chain transfer (RAFT) polymerization. All polymers were characterized in terms of molecular weights, polydispersity indices and compositions by size exclusion chromatography and 1H NMR spectroscopy, respectively. The glass transition (Tg) temperatures of the AEMAx and AnMMAx homopolymers and the AEMA x-b-AnMMAy diblock copolymers were determined using differential scanning calorimetry. These systems were evaluated toward their ability to act as effective dual chemosensors (i.e., amino- and metal-ion sensors) in an organic solvent (chloroform). More precisely, the fluorescence intensity of both the AnMMAx homopolymers and the AnMMA x-b-AEMAy diblock copolymers in solution exhibited a significant decrease in the presence of triethylamine. Moreover, the presence of iron (III) cations were also found to significantly affect the fluorescence signal of the anthracene moieties when those were combined in a block copolymer structure with the AEMA units, due to complex formation occurring between the β-ketoester groups of the AEMAx segment and the cations.
- Demetriou, Maria,Krasia-Christoforou, Theodora
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experimental part
p. 52 - 60
(2012/03/27)
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- Chemically-modified electrodes in photoelectrochemical cells
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Tin oxide and titanium dioxide semiconductor electrodes have been covalently modified by the attachment of functionalized olefins and arenes through surface silanation or via a cyanuric chloride linkage.The excited state and electrochemical properties of the molecules so attached are significantly affected by the semiconductor.Photocurrent measurements and time-resolved laser coulostatic monitoring have been employed to elucidate the mechanism of charge injection on these modified surfaces.
- Fox, Marye Anne,Hohman, James R.,Kamat, Prashant V.
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p. 888 - 893
(2007/10/02)
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