The mechanism of the Suzuki-Heck (SuHe) polymerisation of 2,7-dibromo-9,9-di(n-dodecyl)fluorene (1) with potassium vinyl trifluoroborate (PVTB) for the synthesis of poly(fluorenylene vinylene)s (PFVs) has been investigated. In the first stage, a palladium-catalysed chain-growth AA/B(C)-type polycondensation occurs, as evidenced by the linear trend observed when plotting the molecular weights of the polymer formed against the consumption of the monomer. The chain-growth stage takes place until complete consumption of 1 and allows one to envisage the alternating addition of PVTB (by a Suzuki step) and 1 (by a Heck step) to the growing chain. Such alternating addition seems to proceed through a peculiar catalyst transfer during which the metal is constantly bound to the growing chain, confirmed by MALDI end-group analysis. On prolonging the reaction after the disappearance of 1, a second stage takes place, leading to higher molecular weight polymers, which are formed by the step-growth condensation of the fragments generated in the first stage. The molecular weights of the final PFVs depend on the PVTB/1 feed ratio. Thus, by using a PVTB/1 molar ratio of 1.1, the final PFV was characterised by an M(n) of 39600 Da, whereas when using a PVTB/1 molar ratio of 2.0, the final PFV was characterised by an M(n) of 13200 Da.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1002/chem.201000110 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
Department of Environmental Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea.
Trichloroethylene (TCE) is widely used in various industrial applications, leading to significant environmental and public health concerns due to its toxicity and persistence. Current nonthermal liquid-phase TCE treatment methods, including electrochemical processes, typically produce liquid byproducts that require additional separation steps, limiting their efficiency. To overcome these challenges, this study introduces an innovative electrochemical approach for the direct conversion of TCE gas into less harmful gaseous products, utilizing a Cu/Ni alloy 3D foam electrode integrated with a poly(vinyl alcohol) (PVA)-sodium polyphosphate (SPP) gel membrane system.
View Article and Find Full Text PDFJ Pharm Sci
December 2024
School of Tropical Agriculture and Forestry, Hainan University, 570228, Haikou, China. Electronic address:
Numerous members of the family Picornaviridae, such as the Senecavirus A (SVA) and foot-and-mouth disease virus (FMDV), exhibit thermal instability, resulting in the dissociation of viral particles, which affects the insufficient potency of the vaccine. Based on this characteristic, this study aimed to maintain the thermal stability of SVA by supplementing it with a stabilizer. Excipients, such as sucrose, mannitol, sorbitol, polyethylene glycol (PEG), L-arginine (L-Arg), glutamic acid (Glu), polyvinyl pyrrolidone (PVP), bovine serum albumin (BSA), and potassium chloride (KCl) dissolved in Tris-HCl buffer solution, retained the infectivity of SVA in the thermostability assay.
View Article and Find Full Text PDFMacromolecules
November 2024
Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States.
Silicone bottlebrush copolymers and networks derived from cyclic carbosiloxanes are reported and shown to have enhanced properties and recyclability compared with traditional dimethylsiloxane-based materials. The preparation of these materials is enabled by the synthesis of well-defined heterotelechelic macromonomers with Si-H and norbornene chain ends via anionic ring-opening polymerization of the hybrid carbosiloxane monomer 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane. These novel heterotelechelic α-Si-H/ω-norbornene macromonomers undergo efficient ring-opening metathesis copolymerization to yield functional bottlebrush polymers with accurate control over molecular weight and functional-group density.
View Article and Find Full Text PDFSci Rep
November 2024
Polymeric Materials Research Department, Advanced Technology and New Materials Research Institute (ATNMRI), City of Scientific Research and Technological Applications (SRTA-city), New Borg El-Arab City, 21934, Alexandria, Egypt.
Water scarcity poses a significant challenge to agricultural production, prompting the development of sustainable technologies to optimize water resource utilization. This study focuses on the synthesis and application of a multifunctional poly (vinylpyrrolidone); PVP-based superabsorbent hydrogel (SAH) for controlled release of essential fertilizers (nitrogen, phosphorus, and potassium) and enhanced water retention in soil. The hydrogel was prepared via a facile one-step approach and compared to a control soil without hydrogel amendment.
View Article and Find Full Text PDFJ Org Chem
December 2024
Division of Organic Chemistry, CSIR-National Chemical Laboratory (CSIR-NCL), Pune 411008, India.
Herein, we disclose a simple one-pot method for an efficient regio- and stereoselective synthesis of 1,3,5-triaroylcyclohexanes from aryl vinyl ketones using potassium -butoxide. The developed protocol allows the construction of various symmetrically substituted cyclohexanes in good to excellent yields. The major product also can be converted to the product (all equatorial) conveniently by acid catalysis.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!