Search results for "toluene"
showing 10 items of 429 documents
Vapor-phase testing of the memory-effects in benzene- and toluene-imprinted polymers conditioned at elevated temperature.
2013
Abstract The preparation of polymers imprinted with common aromatic solvents such as benzene and toluene is an under-exploited subject of research. The present study was aimed at the understanding of whether true solvent memory effects can be achieved by molecular imprinting, as well as if they are stable at elevated temperature. A set of copolymers, comprising low and high cross-linking levels, was prepared from four different combinations of functional monomer and cross-linker, namely methacrylic acid (MAA)/ethylene glycol dimethacrylate (EGDMA), methyl methacrylate (MMA)/EGDMA, MAA/divinyl benzene (DVB) and MMA/DVB. Each possible combination was prepared separately in benzene, toluene an…
Liquid–liquid phase behavior of toluene/polyethylene oxide/poly(ethylene oxide-b-dimethylsiloxane) polymer-containing ternary mixtures
2003
The experimental data of phase diagrams for both polyethylene oxide/poly(ethylene oxide-b-dimethylsiloxane) binary and toluene/polyethylene oxide/poly(ethylene oxide-b-dimethylsiloxane) ternary polymer-containing systems was obtained at atmosphere pressure by light scattering method. The critical points for some pre-selected compositions and the pressure effect on the phase transition behavior of ternary system were investigated by turbidity measurements. The chosen system is a mixture of ternary which is one of the very few abnormal polymer-containing systems exhibiting pressure-induced both miscibility and immiscibility. This unusual behavior is related to the toluene concentration in the…
Synthesis of a Fullerene Derivative of Benzo[18]crown-6 byDiels-Alder Reaction: Complexation Ability, Amphiphilic Properties, and X-Ray Crystal Struc…
1993
A fullerene derivative 1 of benzo[18]crown-6 was obtained by Diels-Alder addition of fullerene[60](C60) to the ortho-quinodimethane prepared in situ from 4,5-bis(bromomethyl)benzo[18]crown-6 (3) with Bu4NI in toluene. Extraction experiments show that the complexation of K+ ions strongly increases the solubility of 1 in protic solvents like MeOH. Using Langmuir-Blodgett techniques, monolayers of the highly amphiphilic fullerene-derived crown ether 1 and its K+ ion complex were prepared. An X-ray crystal structure was obtained from a benzene clathrate of comparison compound 2, synthesized by Diels-Alder reaction of C60 with the ortho-quinodimethane derived from 1,2-bis(bromomethyl)-4,5-dimeth…
Mechanism of anionic polymerization of methyl methacrylate in the presence of aluminium alkyls
1995
Methyl methacrylate was polymerized with tert-butyl lithium in the presence of triethylaluminium or triisobutylaluminium at 78°C in toluene. As indicated by GPC and MALDI-TOF mass spectrometry, the polymerization is accompanied by side reactions. The lower oligomers were fractionated by distillation and characterised by NMR, FT-IR, UV and electron impact (EI) mass spectrometry. All these data show that part of the polymer chains are carrying exactly one tert-butyl isoprenyl ketone unit. In order to avoid the formation of tert-butyl isoprenyl ketone a molar ratio of Al/Li>2 is necessary.
Maximizing the emissive properties of CH3NH3PbBr3 perovskite nanoparticles
2015
Highly luminescent and photostable CH3NH3PbBr3 nanoparticles have been prepared by fine-tuning the molar ratio between CH3NH3Br, PbBr2, a medium-size alkyl-chain ammonium salt, and 1-octadecene. The nanoparticles exhibit an excellent photoluminescence quantum yield (ca. 83%) and average recombination lifetime (ca. 600 ns) in toluene dispersion.
Polymer-polymer interaction parameters in solvent/polymer/polymer ternary systems
1981
Abstract Empirical equations defining the relationships between b23 and χ23 interaction parameters for the ternary systems toluene (1)/poly(dimethylsiloxane), PDMS, (2)/polystyrene, PS, (3) and benzene (1)/PDMS(2)/PS(3) have been determined. The dependences of both interaction parameters on the mean molecular weights of the macromolecular components have also been studied. A single dependence of b23 (or χ23) upon the mean molecular weight is found when both polymeric components have intermediate to high molecular weights. However, that single dependence is not found when the molecular size of polymer (2) is low.
Copolymerization of methacryloyl-terminated PMMA macromonomers with methyl methacrylate
1992
Methacryloyl-terminated macromonomers (MM) of polymethylmethacrylate (PMMA) of two different molecular weights were prepared by group transfer polymerization (GTP). They were copolymerized with methyl methacrylate (MMA) by radical polymerization using toluene as the solvent. The relative reactivity of the MM, 1/r1, decreases with increasing initial MM concentration. This is interpreted as a consequence of the increasing viscosity of the reaction medium leading to an increasing diffusion control of the MM addition. At a constant weight ratio of MMA to MM the reactivity of the longer macromonomer is higher than of the shorter one. Increasing the molar ratio [MMA]/[MM], i.e. increasing the ave…
Competitive Adsorption of Functionalized Polymers
1996
The adsorption and desorption of functionalized polystyrene-block-polybutadiene diblock copolymers from dilute solutions in toluene onto silicon wafers are investigated by means of null ellipsometry. The short polybutadiene block is functionalized by a reaction with 4-(3,5-dioxo-1,2,4-triazolidin-4-yl)benzoic acid. On the average there are six functional groups per chain. The polystyrene block does not adsorb on the surface. The adsorption depends on the length of the polystyrene block, and chains with short polystyrene blocks yield higher surface coverage than larger ones. When short and long chains are put together, the short chains displace the long ones in equilibrium conditions nearly …
Probe diffusion in homogeneous diblock copolymers
1998
Forced Rayleigh scattering was used to investigate the diffusion of a photoreactive dye molecule in two homogeneous poly(styrene-b-isoprene) (SI) diblock copolymers with overall molecular weights of approximately 2000. Although diffusion rates were intermediate to TTI transport in homopolymer polystyrene (PS) and polyisoprene (PI), system dynamics appear to be largely dictated in each case by the PI block. The size of the polymer jumping unit, on the other hand, is evaluated from a free-volume analysis of the data, and is found to be governed predominantly by the PS component of the copolymer. The mechanism for tracer diffusion in low-molecular-weight block copolymers appears analogous to t…
Removal of TEX vapours from air in a peat biofilter: influence of inlet concentration and inlet load
2006
This paper presents the results of the study of the removal of toluene, ethylbenzene, and o-xylene (TEX) by biofiltration using a commercial peat as filter-bed material. Runs with a single organic compound in air, and with the mixture of TEX in air, were carried out for at least 55 days in laboratory-scale reactors inoculated with a conditioned culture. The influence of organic compound inlet load and of gas flow rate on the biofilter's performance was studied, including relatively high values of pollutant inlet concentration (up to 4.3 gC m−3 for ethylbenzene, 3.2 gC m−3 for toluene, and 2.7 gC m−3 for o-xylene). Results obtained show maximum elimination capacities of 65 gC m−3 h−1 for o-x…