More Like this

1. Why surface hydrophobicity promotes CO ₂ electroreduction: a case study of hydrophobic polymer N -heterocyclic carbenes

   https://doi.org/10.1039/D3SC02658B  

   Luo, Qiang ; Duan, Hanyi ; McLaughlin, Michael C. ; Wei, Kecheng ; Tapia, Joseph ; Adewuyi, Joseph A. ; Shuster, Seth ; Liaqat, Maham ; Suib, Steven L. ; Ung, Gaël ; et al ( August 2023 , Chemical Science)

   We report the use of polymer N -heterocyclic carbenes (NHCs) to control the microenvironment surrounding metal nanocatalysts, thereby enhancing their catalytic performance in CO 2 electroreduction. Three polymer NHC ligands were designed with different hydrophobicity: hydrophilic poly(ethylene oxide) (PEO–NHC), hydrophobic polystyrene (PS–NHC), and amphiphilic block copolymer (BCP) (PEO- b -PS–NHC). All three polymer NHCs exhibited enhanced reactivity of gold nanoparticles (AuNPs) during CO 2 electroreduction by suppressing proton reduction. Notably, the incorporation of hydrophobic PS segments in both PS–NHC and PEO- b -PS–NHC led to a twofold increase in the partial current density for CO formation, as compared to the hydrophilic PEO–NHC. While polymer ligands did not hinder ion diffusion, their hydrophobicity altered the localized hydrogen bonding structures of water. This was confirmed experimentally and theoretically through attenuated total reflectance surface-enhanced infrared absorption spectroscopy and molecular dynamics simulation, demonstrating improved CO 2 diffusion and subsequent reduction in the presence of hydrophobic polymers. Furthermore, NHCs exhibited reasonable stability under reductive conditions, preserving the structural integrity of AuNPs, unlike thiol-ended polymers. The combination of NHC binding motifs with hydrophobic polymers provides valuable insights into controlling the microenvironment of metal nanocatalysts, offering a bioinspired strategy for the design of artificial metalloenzymes.
2. Chain‐growth polymerization of azide–alkyne difunctional monomer: Synthesis of star polymer with linear polytriazole arms from a core

   https://doi.org/10.1002/pola.29440  

   Gan, Weiping ; Cao, Xiaosong ; Shi, Yi ; Gao, Haifeng ( July 2019 , Journal of Polymer Science)

   This article reports a chain‐growth coupling polymerization of AB difunctional monomer via copper‐catalyzed azide–alkyne cycloaddition (CuAAC) reaction for synthesis of star polymers. Unlike our previously reported CuAAC polymerization of AB_n(n ≥ 2) monomers that spontaneously demonstrated a chain‐growth mechanism in synthesis of hyperbranched polymer, the homopolymerization of AB monomer showed a common but less desired step‐growth mechanism as the triazole groups aligned in a linear chain could not effectively confine the Cu catalyst in the polymer species. In contrast, the use of polytriazole‐based core molecules that contained multiple azido groups successfully switched the polymerization of AB monomers into chain‐growth mechanism and produced 3‐arm star polymers and multi‐arm hyperstar polymers with linear increase of polymer molecular weight with conversion and narrow molecular weight distribution, for example,M_w/M_n ~ 1.05. When acid‐degradable hyperbranched polymeric core was used, the obtained hyperstar polymers could be easily degraded under acidic environment, producing linear degraded arms with defined polydispersity. © 2019 Wiley Periodicals, Inc. J. Polym. Sci.2020,58, 84–90
3. Monodisperse Hyperbranched Polytriazoles as Unimolecular Nanocontainers for Encapsulation of Functional Payloads

   https://doi.org/10.1002/marc.202300121  

   Ma, Kangling ; Jin, Xiuyu ; Gao, Haifeng ( May 2023 , Macromolecular Rapid Communications)

   In this work, a series of polytriazole‐based unimolecular nanocontainers (UNs) with good water solubility, uniformity, and colloidal stability via a bottom‐up chain‐growth copper‐catalyzed azide‐alkyne cycloaddition (co)polymerization that features tunable size, degree of branching (DB), and functionality of the UNs is developed. A broad selection of hydrophobic payload molecules, including Nile red (NR), camptothecin, pyrene, 1‐pyrenemethanol, and IR676, are successfully encapsulated to demonstrate the high versatility of these polymers as UNs. Using NR as a probe guest, the relationship between the encapsulation performance and the structural properties of UNs, including size and DB, is investigated. Furthermore, the localization and dispersity of encapsulated NR are explored and the dependence of payload's dispersity on the DB of UNs is revealed. The payload encapsulated in UNs exhibits tunable release kinetics, determined by either adjusting release conditions or including pH‐responsive structural units in the UNs. Meanwhile, the dyes encapsulated in UNs exhibit improved photostability and stronger resistance to photobleaching. It is expected that these explorations address the size and stability issues widely encounter in current drug/dye nanocarriers and provide a versatile platform of polytriazole‐based UNs for suitable payloads in various applications, including drug delivery and bio‐imaging.
4. Structure and hydrogen bonds of hydrophobic deep eutectic solvent‐aqueous liquid–liquid interfaces

   https://doi.org/10.1002/aic.17427  

   Abbas, Usman L. ; Qiao, Qi ; Nguyen, Manh Tien ; Shi, Jian ; Shao, Qing ( September 2021 , AIChE Journal)

   Hydrophobic deep eutectic solvents (DESs) emerge as candidates to extract organic substrates from aqueous solutions. The DES‐aqueous liquid–liquid interface plays a vital role in the extraction ability of DESs because the nonbulk structure of interfacial molecules could cause thermodynamic and kinetic barriers. One question is how the DES compositions affect the structural features of the interface. We investigate the density profile, dipole moment, and hydrogen bonds of eight hydrophobic DES‐aqueous interfaces using molecular dynamics simulations. The eight DESs are composed of four organic compounds: decanoic acid, menthol, thymol, and lidocaine. The results show the variations of dipole moment and hydrogen bond structure and dynamics at the interfaces. These variations could influence the extraction ability of DES through adjusting the partition and kinetics of organic substrates in the DES‐aqueous biphasic systems. We also analyze the relationship between the variation of these interfacial features and the size and hydrophobicity of DES components.
5. Ion Exchange Gels Allow Organic Electrochemical Transistor Operation with Hydrophobic Polymers in Aqueous Solution

   https://doi.org/10.1002/adma.202002610  

   Bischak, Connor G. ; Flagg, Lucas Q. ; Ginger, David S. ( June 2020 , Advanced Materials)

   Conjugated‐polymer‐based organic electrochemical transistors (OECTs) are being studied for applications ranging from biochemical sensing to neural interfaces. While new polymers that interface digital electronics with the aqueous chemistry of life are being developed, the majority of high‐performance organic transistor materials are poor at transporting biologically relevant ions. Here, the operating mode of an organic transistor is changed from that of an electrolyte‐gated organic field‐effect transistor (EGOFET) to that of an OECT by incorporating an ion exchange gel between the active layer and the aqueous electrolyte. This device works by taking up biologically relevant ions from solution and injecting more hydrophobic ions into the active layer. Using poly[2,5‐bis(3‐tetradecylthiophen‐2‐yl) thieno[3,2‐b]thiophene] as the active layer and a blend of an ionic liquid, 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide, and poly(vinylidene fluoride‐co‐hexafluoropropylene) as the ion exchange gel, four orders of magnitude improvement in device transconductance and a 100‐fold increase in kinetics are demonstrated. The ability of the ion‐exchange‐gel OECT to record biological signals by measuring the action potentials of a Venus flytrap is demonstrated. These results show the possibility of using interface engineering to open up a wider palette of organic semiconductors as OECTs that can be gated by aqueous solutions.