Impact of Alkyl Core Substitution Kinetics in Diaryl Dihydrophenazine Photoredox Catalysts on Properties and Performance in O-ATRP

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(21), P. 14042 - 14051

Published: Oct. 18, 2023

Organocatalyzed atom transfer radical polymerization (O-ATRP) is a controlled method mediated by organic photoredox catalysts (PCs) for producing polymers with well-defined structures. While N,N-diaryl dihydrophenazine PCs have successfully produced low dispersity (Đ < 1.3) in O-ATRP, initiator efficiencies (I* ∼ 60–80%) indicate an inability to achieve targeted molecular weights and been attributed the addition of radicals PC core. In this work, we measure rates alkyl core substitution (AkCS) gain insight into why differing N-aryl group connectivity exhibit differences control. Additionally, evaluate how properties evolve during O-ATRP when non-core-substituted used. 1 1-naphthyl groups position resulted faster AkCS (k1 = 1.21 ± 0.16 × 10–3 s–1, k2 2.04 0.11 s–1) better control at early reaction times as indicated plots weight (number average Mn) vs conversion compared 2 2-naphthyl 6.28 0.38 10–4 1.15 0.07 s–1). The that can influence changing rate formation. increased from initial second substitution, suggesting are modified AkCS. Increased cation (PC•+) oxidation potentials (E1/2 0.26–0.27 V SCE) or longer triplet excited-state lifetimes (τT1 1.4–33 μs) 1b 2b parent 0.21–0.22 SCE, τT1 0.61–3.3 were observed may explain changes performance Insight evaluation formation, properties, will facilitate their use other PC-driven transformations.

Language: Английский

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Chain Shuttle between Dual Sites of a Monomolecular Organocatalyst Enables Controlled Ring-Opening Copolymerization

Macromolecules, Journal Year: 2024, Volume and Issue: 57(17), P. 8401 - 8408

Published: Aug. 22, 2024

The development of a metal-free sequence-controlled polymerization method to yield sustainable polymers is at the forefront polymer science. Here, we demonstrate organocatalytic ring-opening copolymerization (ROCOP) lactide (LA) and ethylene oxide (EO), which challenging due large difference in reactivity between LA (ΔH ≈ −25 kJ mol–1) EO −95 mol–1). In ROCOP process, multifunctional organocatalyst Cat. 2 generates dual active sites amine-thiourea boron, can selectively enable polymerization, respectively. growing-chain shuttle affords poly(LA-co-EO). sequence largely adjusted covering statistics, gradients, blocks, clarified by ratios (by three models) visualizations copolymer microstructure Monte Carlo simulation). We also conduct an exploration how monomer affects thermal mechanical properties resultant oxygen-rich copolymers. results provide insights into methods.

Language: Английский

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O-Methyl-N-nitroisourea as a NCO Surrogate in Cu-Catalyzed Alkane C–H Amidination. A Masked Isocyanate Strategy

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(21), P. 14257 - 14267

Published: Oct. 23, 2023

The Cu-catalyzed C–H activation of alkanes in the presence O-methyl-N-nitroisourea allows a facile entry to O-methyl-N-alkylnitroisoureas, which are shelf-stable isocyanate precursors. latter then readily converted into carbamates and ureas via an uncommon chloride-mediated demethylation process. O-Methyl-N-nitroisourea is available two steps on large scale from urea constitutes easy handle NCO surrogate. methodology has also been applied synthesis methylisocyanate (MIC) precursor, valuable synthon for pharmaceutical agrochemical purposes postfunctionalization polyolefins.

Language: Английский

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N,N′-Bis(imidazolyl)guanidinylphosphines: powerful initiators for conjugate-addition polymerization of Michael-type monomers

Polymer Chemistry, Journal Year: 2024, Volume and Issue: 15(18), P. 1877 - 1883

Published: Jan. 1, 2024

A series of electron-rich phosphines were synthesized, which can effectively initiate the conjugated-addition polymerization Michaeltype monomers to value-added polyolefins.

Language: Английский

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Nanoarcitectonics of Tellurium-Doped Titanium Dioxide: A Catalyst for Improved Electrochemical Performance of Graphene Electrode in Bisphenol A

BioNanoScience, Journal Year: 2024, Volume and Issue: 15(1)

Published: Dec. 4, 2024

Language: Английский

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Imidazolium triflimide-based Brønsted acidic ionic liquid as organocatalyst to trigger the cationic ring-opening polymerization of cyclotrisiloxanes

Polymer Chemistry, Journal Year: 2023, Volume and Issue: 14(41), P. 4693 - 4703

Published: Jan. 1, 2023

Brønsted acidic ionic liquid (BAIL)-catalyzed efficient ROP of D 3 and/or DVi3 in bulk at moderate temperature.

Language: Английский

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Degradation of modified polystyrenes having degradable units by near‐infrared light irradiation

Applied Research, Journal Year: 2023, Volume and Issue: 3(3)

Published: Aug. 22, 2023

Abstract Modified polystyrenes having tertiary ether linkages or carbonate were degrade by irradiation of near‐infrared light (NIR) and subsequent heating. The polymer films containing a photoacid generator commercially available photon upconversion nanoparticle (UCNP) decomposed to form isobutene and/or carbon dioxide NIR thermal decomposition behaviors the polymers investigated discussed in terms chemical structures degradable units. stability was found be order: ester > carbonate. We believe that degradation heating contributes easy recycling composite materials.

Language: Английский

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Organocatalysts for L-Lactide Polymerization: 2-Alkyl- and 2-Aryl-1,1,3,3-Tetramethylguanidines

Published: Jan. 1, 2024

Language: Английский

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Ultrasound-Assisted Degradation of Poly(<i>p</i>-<i>tert</i>-butoxycarbonyloxystyrene) using TiO₂ and Photoacid Generators

Journal of Photopolymer Science and Technology, Journal Year: 2024, Volume and Issue: 37(5), P. 541 - 544

Published: June 25, 2024

Poly(p-tert-butoxycarbonyloxystyrene) (PBOCS), a type of degradable polymer, which generates gaseous compounds, such as carbon dioxide and isobutene, was decomposed after ultrasound-irradiation subsequent heating in the presence titanium oxide (TiO2) photoacid generators (PAGs). The decomposition behaviors PBCOS containing TiO2 PAG were investigated discussed terms chemical structures PAGs. Ultrasound-assisted degradation by UV-vis spectroscopy. We believe that contributes to easy recycling composite materials.

Language: Английский

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Degradation of Modified Polystyrenes Having Degradable Units by Near Infrared Light Irradiation in The Presence of A Photon Upconversion Nanoparticle and A Photoacid Generator

Journal of Photopolymer Science and Technology, Journal Year: 2024, Volume and Issue: 37(2), P. 205 - 208

Published: June 25, 2024

The degradation of modified polystyrenes having tertiary ether linkages or carbonate were carried out by near infrared light (NIR) irradiation and subsequent heating. polymer films containing a photoacid generator photon upconversion nanoparticle (UCNP) decomposed to form isobutene and/or carbon dioxide the NIR thermal decomposition mechanism polymers assisted was investigated discussed in terms thermolysis conditions. Photolysis UV-vis spectroscopy. We believe that heating contributes easy recycling composite materials.

Language: Английский

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