Alternative Synthesis of C60‐Diphenylaminofluorene Derivatives for Nonlinear Photonic Applications: Method of Preparation and Characterization

An alternative synthetic route for the preparation of key intermediate synthons 7‐α‐bromoacetyl‐2‐diphenylaminofluorene (α‐BrDPAF‐H) and 7‐α‐bromoacetyl‐9,9‐dialkyl‐2‐diphenylaminofluorene (α‐BrDPAF‐C_n) was demonstrated. The latter reactions involved the first step of dialkylation of 2‐bromofluorene at C₉ position of the fluorene moiety, the second step of a diphenylamino group attachment at C₂ position of the resulting dialkylfluorene, and the third step of Friedel‐Craft acylation of α‐bromoacetyl group at C₇ position of dialkylated diphenylaminofluorene. From the intermediates α‐BrDPAF‐H and α‐BrDPAF‐C_n, a series of C₆₀‐keto‐DPAF nanostructures, such as the fullerene monoadducts C₆₀(>DPAF‐H) and C₆₀(>DPAF‐C_n), where n is 2, 4, or 10, were synthesized in a reasonable yield. Molecular mass ions of the dyads C₆₀(>DPAF‐H), C₆₀(>DPAF‐C₂), C₆₀(>DPAF‐C₄), and C₆₀(>DPAF‐C₁₀) were clearly detected in positive ion matrix‐assisted laser desorption ionization mass spectrum (MALDI–MS) that confirmed the composition mass of each compound synthesized.     

Organic sol–gel synthesis of microporous molecular networks containing spirobifluorene and tetraphenylmethane nodes

The microporous molecular networks based on rigid tetrafunctional units are synthesized via organic sol–gel polymerization of 2,2′,7,7′‐tetraamino‐9,9′‐spirobifluorene (TASBF) and/or tetrakis(4‐aminophenyl)methane (TAPM) with a diisocyanate, hexamethylene diisocyanate (HDI), or p‐phenylene diisocyanate. This study is performed as an extension of our previous report on the first organic sol–gel method, which enabled the synthesis of microporous molecular networks via a two‐stage mechanism involving the formation of colloidal dispersions of the nanoparticulate molecular networks and their subsequent growth to monolithic networks on solvent evaporation. The sol–gel‐synthesized molecular networks obtained by incorporating TASBF as a network former show improved porosity, processability, and thermal stability than the TAPM‐based system. The improved porosity of TASBF‐based networks is attributed to higher rigidity of the spirobifluorene compared with the tetraphenylmethane units. We also demonstrate the synthesis of mixed organic molecular networks by sol–gel copolymerization of the two network formers, TASBF and TAPM, and a diisocyanate monomer. The sol–gel transformation of TASBF/TAPM/HDI occurred at longer reaction times with increasing the amount of TASBF in the TASBF/TAPM/HDI mixture. The results indicate that the organic sol–gel method can be further optimized by adjusting various synthesis parameters to create new functional organic molecular network materials. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Fabrication of 15 nm curvature radius polymer tip probe on an optical fiber via two-photon polymerization and O2-plasma ashing

Polymer tips with 15 nm curvature radius apexes that are capable of scanning the surface of a sample have been fabricated on the surface of an optical fiber using two-photon photopolymerization (TPP) and O₂-plasma ashing with a SCR500 resin. First, the parent conical polymer tip with a 125 nm curvature radius apex was fabricated via TPP using a continuous scanning method and the accumulation of circular layers. Next, the tip was sharpened using an O₂-plasma ashing process with high reproducibility. As a result, the apex radius of curvature had a maximum reduction to 15 nm. In order to evaluate the performance of the 15 nm curvature radius polymer tip, a 30 nm thick gold layer with holes of 250 nm radius and a single layer of polystyrene beads with a 350 nm radius were imaged using a tuning-fork-based atomic force microscope. The topographic images obtained by the 15 nm polymer tip were improved in width and depth compared with those obtained by the 125 nm polymer tip due to the reduction of the imaging artifacts. This method can also be commonly used to reduce the radius of curvature of the polymer tip in order to achieve more accurate imaging.     

Phase behavior of polymer/diluent/diluent mixtures and their application to control microporous membrane structure

Rechargeable battery separators containing controlled pores were fabricated via the thermally-induced phase separation (TIPS) process. Based on the idea that pores could be manipulated by controlling the liquid–liquid phase separation temperature in the TIPS process, phase boundaries of the polymer–diluent systems were controlled by using diluent mixtures. Phase behaviors of the polymer/diluent/diluent ternary blends consisting of polyethylene (PE) as polymer, and soybean oil (SBO) and dioctyl phthalate (DOP) as diluents were explored. PE/SBO and PE/DOP binary blends, and PE/SOB/DOP ternary blends exhibited typical upper critical solution temperature (UCST) type phase behaviors, and the phase separation temperatures of the PE/SBO blends were higher than those of the PE/DOP blends. When the mixing ratio of the polymer and diluent-mixture was fixed, the phase separation temperature of the PE/SBO/DOP blend initially increased with increasing SBO content in the diluent-mixture passing through a maximum centered at about 80 wt% SBO and decreased beyond this point. Furthermore, the phase separation temperature of the PE/diluent-mixture blend was always higher than that of the PE/SBO blend when the diluent-mixture contained more than or equal to 50 wt% SBO. To understand the observed phase behavior of the blends, thermodynamic analyses based on the lattice-fluid theory were performed. Larger pore membranes were fabricated from the blend when higher phase separation temperatures of the blend were exhibited.     

Identification of genetically modified DNA found in Roundup Ready soybean using gold nanoparticles

The authors describe an SPR sensor chip coated with gold nanoparticles (AuNPs) that enables highly sensitive determination of genetically modified (GM) crops. Detection is based on localized surface plasmon resonance (LSPR) with its known sensitivity to even minute changes in refractive index. The device consists of a halogen light source, a light detector, and a cuvette cell that contains a sensor chip coated with AuNPs. It is operated in the transmission mode of the optical path to enhance the plasmonic signal. The sample solution containing target DNA (e.g. from the GM crop) is introduced into the cuvette with the sensor chip whose surface was functionalized with a capture DNA. Following a 30-min hybridization, the changes of the signal are recorded at 540 nm. The chip responds to target DNA in the 1 to 100 nM concentration range and has a 1 nM detection limit. Features of this sensor chip include a short reaction time, ease of handling, and portability, and this enables on-site detection and in-situ testing.

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Graphical abstract A localized surface plasmon resonance (LSPR)-based nanoplasmonic spectroscopic device enabling a highly sensitive biosensor is developed for the detection of genetically modified (GM) DNA founded in Roundup Ready (RR) soybean.

     

Synthesis of polyolefin‐block‐polystyrene through sequential coordination and anionic polymerizations

Two representative bulk polymers, polyolefin (PO) and polystyrene (PS), were molecularly connected to form PO‐block‐PS by sequentially performing coordination and anionic polymerizations in one pot. Ethylene/1‐octene copolymerization was performed using a typical ansa‐metallocene catalyst, rac‐[Me₂Si(2‐methylindenyl)]₂ZrCl₂, in the presence of (benzyl)₂zinc to grow PO‐chains at the Zn site. Anionic styrene polymerization was subsequently performed using nBuLi·(tmeda) (tmeda, N,N,N′,N′‐tetramethylethylenediamine) initiator to consecutively grow PS‐chains at the Zn site. The composition and the molecular weight of the PO‐blocks were controllable depending on the feed amounts of 1‐octene and (benzyl)₂zinc (1‐octene fraction: ～20, ～40 wt %; PO‐M_w, 77,000–174,000) and the PS‐block size was also controlled (PS‐M_n, ～21,000) with the complete conversion of the styrene monomer. Formation of block copolymers was evident in the GPC curves, TEM images, and strain‐stress curves. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3110–3118