The spectroscopic and photophysical properties of three gold( 1)-acetylide complexes [N (PPh,),] -[Au(CzCPh),], [Au(PPh,)(C-CPh)] and [{Au(C-CPh)},(p-dppe)] [dppe = 1,2-bis(diphenyIphosphino)ethane] are described. X-Ray crystal analysis of the latter showed a weak metal-metal interaction in the solid state with the shortest Au -Au separation being 3.1 53(2) A. The gold(1)acetylide complexes have long-lived and emissive ,(n,n*) excited states in solutions at room temperature. The photoreaction of [Au( PPh,) (C-CPh)] with methyl viologen has been investigated by Stern-Volmer quenching and flash-photolysis experiments.
Well-controlled poly(N-vinylpyrrolidone) (PVP)-grafted silicon surfaces were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) with 1,4-dioxane/water mixtures as solvents and CuCl/5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (Me6TATD) as a catalyst. The thickness of the PVP layer on the surface increased with reaction time, suggesting that the ATRP grafting of N-vinylpyrrolidone (NVP) from the silicon surfaces was a well-controlled process. The water contact angle and X-ray photoelectron spectroscopy (XPS) were used to characterize the modified surfaces. The protein adsorption property of the PVP-grafted surfaces was evaluated using a radiolabeling method. Compared with unmodified silicon surfaces, a Si-PVP60 surface with a PVP thickness of 15.06 nm reduced the level of adsorption of fibrinogen, human serum albumin (HSA), and lysozyme by 75, 93, and 81%, respectively. Moreover, the level of fibrinogen adsorption decreases gradually with an increase in PVP thickness. However, no significant difference in fibrinogen adsorption was found when the PVP layer was thicker than the critical thickness of 13.45 nm.
Polymer self-assembly has been one
of the most important strategies
for preparation of multicompartment micelles (MCMs). However, the
traditional self-assembly techniques are constrained by limited common
solvent, complex kinetic factors, low solids content, etc. Polymerization-induced
self-assembly (PISA) is a novel technique for preparation of polymer
assemblies at high solids content and has been exploited to produce
MCMs. Nevertheless, the morphology evolution of the MCMs obtained
through PISA has not yet been well understood. Herein, we study the
compartmentalization behaviors of a series of MCMs constituted by
poly(N,N-dimethylaminoethyl
methacrylate)-b-poly(benzyl methacrylate)-b-poly(2-perfluorohexylethyl methacrylate) (PDMA-b-PBzMA-b-PFHEMA) triblock terpolymers,
which were synthesized by seeded reversible addition–fragmentation
chain transfer (RAFT) dispersion polymerization of FHEMA using PDMA-b-PBzMA micelles, wormlike micelles, or vesicles as the
seeds. Because of the strong incompatibility between PBzMA and PFHEMA,
MCMs with abundant compartmentalized nanostructures were produced.
Phosphotungstic acid- and RuO4-stained TEM images of these
MCMs indicate that their morphologies are controlled by both the DPs
of PBzMA and PFHEMA. Our results suggest that PISA could serve as
a reliable platform for revealing the compartmentalization behaviors
of polymeric assemblies.
Design of functional carbon-based nanomaterials from metal-organic frameworks (MOFs) has attracted soaring interests in recent years. However, a MOF-derived strategy toward two-dimensional (2D) nanomaterials remains a great challenge. In this work, we develop a layered Ni-hexamine framework as efficient precursor to prepare a 2D NiSe/N-rich carbon nanocomposite by a simple pyrolysis and subsequent selenization process. In the 2D NiSe/N-rich carbon nanocomposite, NiSe nanoparticles with diameters of ca. 75 nm are homogeneously distributed in the N-rich carbon nanosheets. When serving as anode materials for sodium-ion batteries, the 2D nanocomposites exhibit a high reversible capacity of 410 mAh g at 1 A g and maintain a value of 255 mAh g even at 10 A g. The excellent electrochemical performance can be attributed to the synergistic effects between the N-rich carbon nanosheets and NiSe nanoparticles. More importantly, the hexamine-based MOFs can be regarded as new and powerful platforms for the fabrication of 2D N-rich carbon-based nanomaterials, which is of great importance for various potential applications.
Accurate monitoring of physiological temperatures is important for the diagnosis and tracking of various medical conditions. This work presents the design, fabrication, and characterization of temperature sensors using conductive polymer composites (CPCs) patterned on both flexible and stretchable substrates through both drop coating and direct ink writing (DIW). These composites were formed using a high melting point biopolymer polyhydroxybutyrate (PHB) as the matrix and the graphenic nanomaterial reduced graphene oxide (rGO) as the nanofiller (from 3 to 12 wt%), resulting in a material that exhibits a temperature-dependent resistivity. At room temperature the composites exhibited electrical percolation behavior. Around the percolation threshold, both the carrier concentration and mobility were found to increase sharply. Sensors were fabricated by drop-coating PHB-rGO composites onto ink-jet printed silver electrodes. The temperature coefficient of resistance was determined to be 0.018 /°C for pressed rGO powders and 0.008 /°C for the 3 wt% samples (the highest responsivity of all composites). Composites were found to have good selectivity to temperature with respect to pressure and moisture. Thermal mapping was demonstrated using 6 × 7 arrays of sensing elements. Stretchable devices with a meandering pattern were fabricated using DIW, demonstrating the potential for these materials in healthcare monitoring devices.
A series of polymerization-induced self-assembly (PISA) formulations are developed based on reversible addition-fragmentation chain-transfer (RAFT) dispersion polymerization of semi-fluorinated methacrylates. Alcoholic RAFT dispersion polymerization of 2-(perfluorobutyl)ethyl methacrylate (FBEMA), 2-(perfluorohexyl)ethyl methacrylate (FHEMA), and 2-(perfluorooctyl)ethyl methacrylate (FOEMA) is systematically evaluated to extend the general usability of semi-fluorinated methacrylates to PISA. The nanostructure of the assemblies is correlated to the side-chain length of the monomer: RAFT dispersion polymerization of FBEMA produces spherical micelles, wormlike micelles, and vesicles depending on its degree of polymerization (DP), while only spheres are generated for the PISA of FHEMA. PISA of FOEMA generates liquid crystalline cylindrical micelles, whose diameter increases with the DP of FOEMA. These results demonstrate the general feasibility of semi-fluorinated methacrylates to PISA. Besides, PISA of FHEMA is also realized in a variety of solvents, including iso-propanol, toluene, dioxane, and dimethyl formamide, exhibiting the superior solvent serviceability of the PISA formulations based on semi-fluorinated methacrylates.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.