A type of thermosensitive ionic microgel was successfully prepared via the simultaneous quaternized cross-linking reaction during the surfactant-free emulsion copolymerization of N-isopropylacrylamide (NIPAm) as the main monomer and 1-vinylimidazole or 4-vinylpyridine as the comonomer. 1,4-Dibromobutane and 1,6-dibromohexane were used as the halogenated compounds to quaternize the tertiary amine in the comonomer, leading to the formation of a cross-linking network and thermosensitive ionic microgels. The sizes, morphologies, and properties of the obtained ionic microgels were systematically investigated by using transmission electron microscopy (TEM), dynamic and static light scattering (DLS and SLS), electrophoretic light scattering (ELS), thermogravimetric analyses (TGA), and UV-visible spectroscopy. The obtained ionic microgels were spherical in shape with narrow size distribution. These ionic microgels exhibited thermosensitive behavior and a unique feature of poly(ionic liquid) in aqueous solutions, of which the counteranions of the microgels could be changed by anion exchange reaction with BF4K or lithium trifluoromethyl sulfonate (PFM-Li). After the anion exchange reaction, the ionic microgels were stable in aqueous solution and could be well dispersed in the solvents with different polarities, depending on the type of counteranion. The sizes and thermosensitive behavior of the ionic microgels could be well tuned by controlling the quaternization extent, the type of comonomer, halogenated compounds, and counteranions. The ionic microgels showed superior swelling properties in aqueous solution. Furthermore, these ionic microgels also showed capabilities to encapsulate and release the anionic dyes, like methyl orange, in aqueous solutions.

We report on Bi 2 Sr 2 CaCu 2 O 8 (BSCCO) intrinsic Josephson junction stacks with improved cooling, allowing for a remarkable increase in emission frequency compared to the previous designs. We started with a BSCCO stack embedded between two gold layers. When mounted in the standard way to a single substrate, the stack emits in the range of 0.43-0.82 THz. We then glued a second, thermally anchored substrate onto the sample surface. The maximum voltage of this better cooled and dimension-unchanged sample was increased and, accordingly, both the emission frequencies and the tunable frequency range were significantly increased up to 1.05 THz and to 0.71 THz, respectively. This double sided cooling may also be useful for other "hot" devices, e.g., quantum cascade lasers. V C 2014 AIP Publishing LLC. [http://dx.

4-(2-Pyridylazo)-resorcinol (PAR) functionalized thermosensitive ionic microgels (PAR-MG) were synthesized by a one-pot quaternization method. The PAR-MG microgels were spherical in shape with radius of ca. 166.0 nm and narrow size distribution and exhibited thermo-sensitivity in aqueous solution. The PAR-MG microgels could optically detect trace heavy metal ions, such as Cu(2+), Mn(2+), Pb(2+), Zn(2+), and Ni(2+), in aqueous solutions with high selectivity and sensitivity. The PAR-MG microgel suspensions exhibited characteristic color with the presence of various trace heavy metal ions, which could be visually distinguished by naked eyes. The limit of colorimetric detection (DL) was determined to be 38 nM for Cu(2+) at pH 3, 12 nM for Cu(2+) at pH 7, and 14, 79, 20, and 21 nM for Mn(2+), Pb(2+), Zn(2+), and Ni(2+), respectively, at pH 11, which was lower than (or close to) the United States Environmental Protection Agency standard for the safety limit of these heavy metal ions in drinking water. The mechanism of detection was attributed to the chelation between the nitrogen atoms and o-hydroxyl groups of PAR within the microgels and heavy metal ions.

A functional ionic microgel sensor array was developed by using 1-(2-pyridinylazo)-2-naphthaleno (PAN)- and bromothymol blue (BTB)-functionalized ionic microgels, which were designed and synthesized by quaternization reaction and anion-exchange reaction, respectively. The PAN microgels (PAN-MG) and BTB microgels (BTB-MG) were spherical in shape with a narrow size distribution and exhibited characteristic colors in aqueous solution in the presence of various trace-metal ions, which could be visually distinguished by the naked eye. Such microgels could be used for the colorimetric detection of various metal ions in aqueous solution at submicromolar levels, which were lower than the U.S. Environmental Protection Agency standard for the safety limit of metal ions in drinking water. A total of 10 species of metal ions in aqueous solution, Ba, Cr, Mn, Pb, Fe, Co, Zn, Ni, Cu, and Al, were successfully discriminated by the as-constructed microgel sensor array combined with discriminant analysis, agglomerative hierarchical clustering, and leave-one-out cross-validation analysis.

Capture and conversion of CO2 are of great importance for environment-friendly and sustainable development of human society. Poly(ionic liquid)s (PILs) combine some unique properties of ILs with that of polymers and are versatile materials for CO2 utilization. In this contribution, we briefly outline innovative poly(ionic liquid)s emerged over the past few years, such as polytriazoliums, deep eutectic monomer (DEM) based PILs, and polyurethane PILs. Additionally, we discuss their advantages and challenges as materials for Carbon Capture and Storage (CCS), and the fixation of CO2 into useful materials. KeywordsPoly(ionic liquid); CO2 capture; CO2 catalysis; CO2 utilization adsorption processes (PTSA). Materials under discussion include micro/meso-porous silica or zeolites [13,14], metal-organic frameworks (MOFs) [15][16][17][18][19], covalent organic frameworks (COFs) [20,21], carbonaceous materials [22,23], and more [24,25]. Among them, the hybrid MOFs (up to 27 wt%) and zeolites (up to 18 wt%) exhibit exceptionally high CO2 uptake around room temperature and atmospheric pressure. [26,27] A still very valuable review of different material classes for CO2 capture by adsorption, also with respect to technical issues, was provided by Hedin and coworkers recently [28]. Material combinations such as zeolite/activated carbon have already been implemented into pilot-scale in real power plants. [29] Along this line, there is considerable interest in developing alternative techniques. Since Blanchard et al. [30] firstly reported CO2 capture by ionic liquids (ILs), ILs have attracted much attention in the field of gas capture and separation. ILs carry unique properties, such as negligible vapor pressure, low flammability, high thermal stabilities, excellent gas selectivity, and tunable properties, just to name a few, which make them multifunctional [31]. However, the high viscosity and the associated relatively low CO2 sorption/desorption rates of ILs [32][33][34] hamper their application in gas capture.Recent success in poly(ionic liquid)s (PILs), i.e. the polymeric product of ILs, promotes their usage in and beyond CO2 sorption due to a variety of new features of PILs in comparison to ILs [8,[35][36][37][38]. PILs are composed of covalently linked IL species [31], and carry features of macromolecules, thus elegantly combining some unique properties and functions of ILs with that of polymers (e.g. easy processability and shape durability). Although suffering from a relatively poor capacity of CO2 (generally <10 wt%) and a high cost in comparison to commercial CO2 absorbents, the affinity of PILs towards CO2 can be tailor-made through judicious choice of the IL groups and the polymer backbones, as well as the polymer structures [39][40][41][42]. Thus the PIL technology in CO2 utilization encompasses not only CO2 capture because of its scientific interest, but also the catalytic CO2 activation, sensing, and conversion to value-added chemical feedstocks and high-end polymers. This contribution presents a brief overview of ne...

We describe the enhanced mechanophore activation within nanosized core–shell micelles, which also present temperature and ultraviolet (UV) light-responsive properties. The model micelle was fabricated by the self-assembly of an amphiphilic block copolymer of poly­(tert-butyl acrylate-b-N-isopropyl­acrylamide) with one spiropyran (SP) moiety at the midpoint of chain [SP-(t-BA88-b-NIPAM62)2, P2]. Micellization of P2 in tetrahydrofuran (THF)/water mixed solvent enhanced the reactivity of the electrocyclic ring-opening reaction of SP to merocyanine (MC) isomer under sonication because micellization caused SP-centered PtBA block entangled and partially swelled in the micellar core and the increase of the dielectric constant of the medium around the SP, which could facilitate the conversion of SP to MC. This new enhanced mechanophore activation model demonstrated here is valuable as a probe to detect stress activation within nanosized particles and to design multiple-responsive materials.

We used one-dimensional coupled sine-Gordon equations combined with heat diffusion equations to numerically investigate the thermal and electromagnetic properties of a 300 µm long intrinsic Josephson junction stack consisting of N = 700 junctions. The junctions in the stack are combined to M segments where we assume that inside a segment all junctions behave identically. Most simulations are for M = 20. For not too high bath temperatures there is the appearence of a hot spot at high bias currents. In terms of electromagnetic properties, robust standing wave patterns appear in the current density and electric field distributions. These patterns come together with vortex/antivortex lines across the stack that correspond to π kink states, discussed before in the literature for a homogeneous temperature distribution in the stack. We also discuss scaling of the thermal and electromagnetic properties with M , on the basis of simulations with M between 10 and 350.

Degradable thermosensitive ionic microgels were synthesized via surfactant-free emulsion polymerization (SFEP) of N-isopropylacrylamide (NIPAm) and 1-vinylimidazole (VIM) at 70 °C with degradable 1,4-phenylene bis­(4-bromobutanoate) or 1,6-hexanediol bis­(2-bromopropionate) as quaternized cross-linkers. VIM could be quaternized by 1,4-phenylene bis­(4-bromobutanoate) or 1,6-hexanediol bis­(2-bromopropionate), leading to the formation of degradable cross-linking network and ionic microgels. Combined techniques of transmission electron microscopy (TEM), dynamic light scattering (DLS), electrophoretic light scattering (ELS), UV–vis spectroscopy, FT-IR spectra, and gel permeation chromatography (GPC) were employed to systematically investigate the sizes, morphologies, and properties of the obtained microgels before and after degradation as well as the degradation mechanism. The obtained microgels were spherical in shape with narrow size distribution and exhibited thermosensitive behavior and controllable degradation. The disintegration of the microgels was confirmed to be resulted from the hydrolysis of ester bonds of the cross-linkers. The degradation rate of the obtained microgels could be regulated by tuning the pH value of microgel suspensions. The PNI-Ph series of microgels fabricated with 1,4-phenylene bis­(4-bromobutanoate) as the cross-linking agent could gradually degrade even in neutral solution with lifetimes of 44–53 h, depending on the quaternization ratio. The degradation of PNI-Ph series of microgels experienced two reaction processes, that is, the hydrolysis of ester bonds of the cross-linkers and the oxidation of generated hydroquinone to form benzoquinone. It was also demonstrated that different silica nanostructures could be fabricated by using such degradable thermosensitive ionic microgels as the template at various temperatures.