Liquid Oligomers Research Articles

Universal measuring cell and installation for determining dielectric parameters during the transition from a liquid oligomer to a solid polymer

This paper presents the design of a new installation and a universal measuring cell that allows determining the dielectric properties of materials in various states of aggregation.The data of dielectric permittivity studies for the initial components of the oligomeric binder, ED-20 epoxy oligomer and aminetype hardener triethylenetetramine (TETA), as well as the kinetics of its curing process, established by the change in dielectric permittivity, were obtained for the first time. It is also shown that the maximum temperature of the curing reaction of the ED20+TETA system can be determined from dielectric permittivity data.

Large-Size ultrathin mica nanosheets: Reinforcements of biobased PEF polyester

Due to the superior physical properties and high-level alignment of the nanoscale building blocks, assembly of high-quality two-dimensional (2D) nanosheets into macroscopic engineering structure materials can achieve many unexpected performance. Natural mica nanosheets (MNSs) are abundant and with superlative properties, showing huge prospect for engineering structural materials. However, the difficulty of the mass production with large size and high aspect ratio are the current factors that limit this. Inspired by the well-known scotch-tape exfoliation, herein we develop a gummy-tape exfoliation (GTE) method by using liquid oligomers as mediums in ball-milling process to massively produce large-size and ultrathin MNSs. As a confirmation, the obtained MNSs show a record high aspect ratio of ≈1320 and a large actual yield of ∼ 80 %. A transparent biobased aromatic polyester nanocomposite film made of such MNSs and polyethylene furandicarboxylate (PEF) matrix possesses remarkably improved mechanical, barrier properties, and UV-shielding performances at an extremely low filler loading (≤0.5 vol%), making it a novel potential engineering material for packing fields in foods, drugs, and electronic products, etc.

Accelerated Water Desorption of Oligomeric Poly(ethylene glycol) by Addition of Poly(propylene glycol) for Energy-Efficient Water Recovery Systems.

Adsorbents are used to recover water vapor from the atmosphere in desiccant air conditioning (DAC) and atmospheric water harvesting (AWH) systems. Solid adsorbents have been conventionally used in these systems, though liquid adsorbents are considered to be more effective for energy-efficient fluidic thermosystems because of their low regeneration temperatures (45-70 °C). While most previous studies have focused on improving the adsorption performance, the desorption performance of adsorbents can also be a critical factor in improving the energy efficiency of these systems. Thus, this study aimed to improve the water desorption efficiency, focusing on the liquid adsorbents. We found that mixing hydrophobic molecules into a liquid adsorbent decreases the desorption temperature and increases the water-desorption efficiency. Oligomeric poly(ethylene glycol) (PEG), a common moisture-adsorbing liquid oligomer used in detergents and cosmetics, was selected as the liquid adsorbent. Oligomeric poly(propylene glycol) (PPG), which has a structure analogous to PEG and lower hygroscopicity, was selected as the hydrophobic molecule. Water adsorption and desorption experiments showed that the mixture of PPG with PEG promoted the desorption of water molecules beyond that of PEG, while thermogravimetric differential thermal analysis revealed a decrease in the water desorption temperature with increasing PPG content. The improved desorption efficiency was ascribed to the likely water adsorption equilibrium between PEG and PPG in the blend; water molecules are preferentially desorbed from PPG, which has weaker water-adsorbate interactions. The proposed concept is expected to be incorporated into various hygroscopic liquids to develop energy-efficient liquid adsorbents for DAC and AWH.

Comparative Reactivity of Different Polyols in the PET Saponification Process

This work is concerned with polyethylene terephthalate (PET) saponification by different potassium compounds in various polyols as well as biodiesel’s main by-product, crude glycerol. It was established that reaction conditions (initial PET/K+ molar ratio, reaction time, etc.) could control the molecular weight of obtained oligomeric products. In ethylene glycol, depolymerization proceeds rapidly, and already at 10–30 min, PET is completely dissolved in the reaction mixture with the formation of liquid oligomers. Then, these oligomers react with potassium compounds, and after 200 min of the process, there are only solid, low-molecular-weight products (dipotassium terephthalate, monomers, and dimers). At the same time, PET saponification in pure glycerol is less effective, and solid polyether flakes could not fully decompose even after 200 min of the process. Crude glycerol takes the middle position between pure polyols. Based on the obtained data, an improved kinetic model was developed, and rate constants were estimated. This model takes into account PET saponification by potassium salts as well as direct PET glycolysis. Ethylene glycol is formed in situ by transesterification between fatty acid ethylene glycol esters and glycerol in the case of pure and crude glycerol.

Photomechaelectric nanogenerator

<h2>Summary</h2> Metal and inorganic or organic conjugate semiconductors can convert solar energy into electricity through the well-known external photoelectric effect and internal photovoltaic effect, respectively. The photoelectric effect cannot be detected in electron-insulated polymers due to a lack of free electrons or the redistribution of holes and electrons under illumination. Here, we report a subtle method to efficiently convert UV-light energy into electricity for electron-insulated co-polymers via a photomechaelectric (PME) effect, in which a PME effect means that photo induces isomerization of photosensitive segments and further results in generating dynamic dipoles and equal amounts, but opposite signs, of induced charges at electrodes. To this aim, functional azobenzene (AZO) and imidazole ionic liquid (ILO) oligomers have been used as photoisomer and dipole units, respectively. The produced electron-insulated AZO-<i>co</i>-ILO co-polymer-based nanogenerator can directly output an alternating current (up to 5.8 V and 247 μA) under UV illumination, implying extensive potential applications in self-powered electronic devices.

Synthesis of heterogeneous metathesis catalysts for the development of sustainable processes

&#x0D; In recent decades, it has been tried to develop processes that involve the use of catalysts that can be recovered from the reaction medium, to make them green and sustainable. Approximately, 90 % of all processes in chemistry and petrochemicals use heterogeneous catalysts. In this sense, the supported heterogeneous catalysts present advantages in the purification of the products and the reduction of costs. In the present work, the synthesis of a new heterogeneous supported catalyst, highly active in the metathesis reaction, based on a ruthenium-alkylidene complex, was carried out. The new catalyst was obtained by anchoring of dichloro[1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene](benzylidene)(tricyclohexylphosphine)ruthenium (II) (second generation Grubbs) in various silylated polymeric gels, based on 2-norbornene-5,6-dicarboxylic anhydride (NDA) and cis-cyclooctene (CO) cross-linked with various percentages of 3-aminopropyltriethoxysilane (APTES) (5%, 15%, 100%). The new heterogeneous catalyst was successfully used in the depolymerization reaction via metathesis of natural rubber from Oaxaca (HNO), using 1-octene as CTA; observing the formation of liquid oligomers, achieving a decrease in molecular weight from 137.941 g/mol to 297 g/mol; proving, in this way, its high effectiveness.&#x0D;

Hydrothermal Depolymerization of Kraft Lignins with Green C1–C3 Alcohol–Water Mixtures

Lignin is a potential renewable raw material for synthesis of aromatic molecules and materials. Particularly, Kraft-type lignins are abundantly available as a byproduct of wood and paper industries. Currently, there are practically no valuable products made using this highly complex polymer. Within this work, we have investigated the straightforward, high-yield depolymerization of two different technical lignins (Indulin AT and alkaline lignin) using only a mixture of green short-chain (C1–C3) alcohols and water as solvents. As shown here, at a temperature of 220 °C, autogenous pressure, and isopropanol/water as a co-solvent medium, it is possible to cleave Kraft lignin without char-forming side reactions. The obtained so-called “light” oil contains guaiacol-based monomeric units of 23 wt % yield together with liquid oligomers of 13 wt % yield combining liquid–liquid and solid–liquid extraction. Two-dimensional nuclear magnetic resonance analysis of lignin residues showed that the isopropanol/water treatment caused a marked breakdown of the intermolecular β–O–4 and β–β bonds; thus, the depolymerization produced monomers and lignin residues with lower molecular weight. The results suggested a synergistic effect between isopropanol and water. No sign of repolymerization reactions could be observed with this process.

Rare-earth metal complexes derived from the acids Ph2C(X)CO2H (X= OH, NH2): Structural and ring opening polymerization (ROP) studies

Treatment of Ln(NO3)3.6H2O (Ln = La, Ce) with an equimolar amount of 2,2′-diphenylglycine (DpgH) in ethanol afforded the corresponding hexacoordinated complexes (DpgH±)3Ln(NO3)3.H2O (DpgH± = zwitterionic 2,2′-diphenylglycine, Ln = La (1), Ce (2)). The spectroscopic and structural features of these compounds have been investigated. Similar reactions with the related benzilic acid (BenzH2) were unsuccessful. The catalytic behaviour of 1 and 2 in the homo- and copolymerization of ε-caprolactone (ε-CL) and rac-lactide (r-LA) has been investigated herein. In the case of ε-CL, the two complexes exhibited comparable activity, allowing for complete monomer conversion under aerobic and solvent-free conditions at 150 °C in 24 h. With respect to the ROP of r-LA, 1 was found to be completely inactive, while only 8% conversion was achieved in the presence of 2. Liquid oligomers were isolated during ε-CL/r-LA co-polymerization in the presence of both complexes. The catalytic activity of the pre-ligands DpgH and BenzH2 (i.e. metal-free) was also examined. Interestingly, only BenzH2 was found to be active, although it required a higher catalyst loading and the presence of benzyl alcohol as co-activator.

Vulcanization behavior and mechanical properties of isoprene-modified silica reinforced butyl rubber composites

Butyl rubber was reinforced by the isoprene-modified silica. The modified silica was prepared via chemical modification by a hydrophobic and reactive oligomeric liquid isoprene rubber in a solvent. Thereafter butyl rubber was compounded with the modified silica and vulcanized by thermal compression molding process. Their properties were studied using oscillating disk rheometer (ODR), differential scanning calorimeter (DSC), dynamic mechanical analyzer (DMA), and universal testing machine (UTM). The surface modification of the silica moved up the curing time and enhanced apparently tensile strength and modulus of the rubber composites. In conclusion, cure behavior and mechanical properties of butyl rubber/silica composites can be controlled by chemical modification of the silica surface using rubber molecules.

Synthesis of mesoporous Co/Al-SBA-15 catalyst and application to ethylene hydropolymerization

Liquid fuel, a mixture of ethylene’s liquid oligomer, from ethylene was successfully carried out by oligomerization of ethylene in the presence of Co/Al-SBA-15. The mesoporous Co/Al-SBA-15 catalyst was prepared through impregnation of varies amount of Co (5, 7.5, 10, and 15 wt.%) into Al-SBA-15. The conversion of ethylene was performed at atmospheric pressure and 190°C in the presence of CO and H2, and 08 hour/day. Through all of Co impregnated proportion on Al-SBA-15 (5, 7.5, 10 and 15 wt.%), the GC-MS result showed the liquid hydrocarbon were obtained as naptha (15.37÷30.53%), gasoline (10.65÷21.17%), kerosene (1.49÷20.50%) and diesel (3.21÷3.69%) fraction. The highest conversion of ethylene into liquid fuel was found in the presence of 7.5%Co/Al-SBA-15, with the yield of 20%. Byproducts was also obtained during the conversion, e.g. 3,4,5-methylnonane, 2,3 dimethylnonane, 3-methylheptane, and 4-ethylheptane, which was approximately 30% of total product volume.

Lithium bis(oxalate)borate crosslinked polymer electrolytes for high-performance lithium batteries

Solid electrolytes play a vital role in solid-state Li secondary batteries, which are promising high-energy storage devices for new-generation electric vehicles. Nevertheless, obtaining a suitable solid electrolyte by a simple and residue-free preparation process, resulting in a stable interface between electrolyte and electrode, is still a great challenge for practical applications. Herein, we report a self-crosslinked polymer electrolyte (SCPE) for high-performance lithium batteries, prepared by a one-step method based on 3-methoxysilyl-terminated polypropylene glycol (SPPG, a liquid oligomer). It is worth noting that lithium bis(oxalate)borate (LiBOB) can react with SPPG to form a crosslinked structure via a curing reaction. This self-formed polymer electrolyte exhibits excellent properties, including high room-temperature ionic conductivity (2.6 × 10−4 S cm−1), wide electrochemical window (4.7 V), and high Li ion transference number (0.65). The excellent cycling stability (500 cycles, 83%) further highlights the improved interfacial stability after the in situ formation of SCPE on the electrode surface. Moreover, this self-formation strategy enhances the safety of the battery under mechanical deformation. Therefore, the present self-crosslinked polymer electrolyte shows great potential for applications in high-performance lithium batteries.

The effect of the modification of an epoxy resin by liquid oligomers on the physical-mechanical properties of composites

The effect of the modification of an epoxy resin by liquid oligomers on the physical-mechanical properties of composites

Reversible control of ionic conductivity and viscoelasticity of organometallic ionic liquids by application of light and heat.

Ru-containing ionic liquids [Ru(C5H5){C6H3(OC6H12CN)3}][N(SO2F)2] (1) and [Ru(C5H5){C6H5(OC3H6CN)}][N(SO2F)2] (2), having different numbers of substituents, were reversibly converted to coordination polymer solids and oligomeric liquids, respectively, by UV photoirradiation and heating. This feature enabled the control of their ionic conductivities and viscoelastic properties.

Scalable electric-field-assisted fabrication of vertically aligned carbon nanotube membranes with flow enhancement

We report a solution-based approach for fabricating vertically aligned carbon-nanotube (VACNT) membranes, which improves on the unaligned nature of CNT mixed-matrix membranes. This approach addresses important challenges regarding scalability and incorporation of different types and sizes of nanotube as pores in a membrane. In a new, solvent-deposition approach, CNTs are dispersed and then aligned and concentrated via electro-deposition from an organic solvent, using a composite AC + DC electric field to form aligned CNT arrays. This enables VACNT number densities that are two orders-of-magnitude higher than possible from direct suspension of CNTs in the liquid oligomer. The solvent is then replaced by a UV-curable oligomer, which is selectively cured to form macroscopic membranes of highly controlled thickness. After plasma etching to open pores, the VACNT membranes are shown to be permeable, and to have pore sizes consistent with flow through internal channels of the CNTs. In a first for field-aligned, solution-fabricated VACNT membranes, the pores show substantial, 100–300×, gas-flow enhancement compared to theory, similar to membranes fabricated via less scalable methods (i.e., by CVD growth of already aligned CNT forests). The solution-based, electric-field-assisted approach aligns nanotubes of different sizes and types grown by any means, and is scalable to the efficient fabrication of large-area VACNT membranes for a variety of important applications.

Wetting, meniscus structure, and capillary interactions of microspheres bound to a cylindrical liquid interface.

Wetting, meniscus structure, and capillary interactions for polystyrene microspheres deposited on constant curvature cylindrical liquid interfaces, constructed from nonvolatile ionic or oligomeric liquids, were studied by optical interferometry and optical microscopy. The liquid interface curvature resulted from the preferential wetting of finite width lines patterned onto planar silicon substrates. Key variables included sphere diameter, nominal (or average) contact angle, and deviatoric interfacial curvature. Menisci adopted the quadrupolar symmetry anticipated by theory, with interfacial deformation closely following predicted dependences on sphere diameter and nominal contact angle. Unexpectedly, the contact angle was not constant locally around the contact line, the nominal contact angle varied among seemingly identical spheres, and the maximum interface deviation did not follow the predicted dependence on deviatoric interfacial curvature. Instead, this deviation was up to an order-of-magnitude larger than predicted. Trajectories of neighboring microspheres visually manifested quadrupole-quadrupole interactions, eventually producing square sphere packings that foreshadow interfacial assembly as a potential route to hierarchical 2D particle structures.

Liquid crystalline non-linear S-shaped oligomers consisting of azobenzene and biphenylene units: synthesis, characterisation and influence of central spacer

ABSTRACTA series of non-linear S-shaped liquid crystal oligomers wherein the molecule consists of biphenylene moiety as a central core unit and two symmetrical side arms azobenzene moieties joined to catechol as a linkage group have been successfully synthesised and characterised. The members in this series possess different inner spacer with carbon number n ranging from 4 to 9 while the outer spacer length located in azobenzene moieties are remains unaltered. The members with even parity exhibit monotropic phase, whereas homologues with odd parity display enantiotropic phase. The appearance of nematic, smectic A and smectic B phases was validated with texture observation under polarised light and X-ray diffraction (XRD). The XRD study on the S-shaped oligomer indicates that the arrangement of smectic phase exists as an intercalated structure. The S-shaped oligomer shows photoisomerisation properties in solution whereby the trans to cis isomerisation for this molecule is accomplished 1140 s, whereas reverse process under thermal back reaction occurred in 4620 min.

Liquid crystalline oligomers derived from cholesterol: synthesis and columnar mesomorphism

ABSTRACTThe novel columnar liquid crystals based on symmetric hairpin-shaped cholesterol tetramers bridged by rigid or hydrogen-bonding Schiff-base spacers were prepared by reacting cholesterol dimer with phenylenediamines or dihydrazides in yields of 70–85%. Structural characterisation of these new compounds had been achieved by infrared, nuclear magnetic resonance and mass spectrometry. Their mesomorphic properties were investigated by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction. They exhibited good hexagonal columnar mesophase with three molecules in a disc of the columnar hexagonal state. This study implied that the symmetric cholesterol tetramers with rigid cores or hydrogen-bonding cores prefer to columnar mesophase.

An integrated process for production of jet-fuel range olefins from ethylene using Ni-AlSBA-15 and Amberlyst-35 catalysts

An integrated process for the production of jet-fuel range olefins from ethylene was established by combining oligomerization of ethylene over the bifunctional Ni-AlSBA-15 catalyst with subsequent co-oligomerization of the liquid oligomer mixture over an Amberlyst-35 ion-exchange resin catalyst. The mesoporous Ni-AlSBA-15 catalyst was prepared by alumination of SBA-15 using sodium aluminate, followed by sequential ion exchange with NH4+ and Ni2+ ions. The Ni-AlSBA-15 (1.9wt% Ni and Si/Al=9) catalyst showed good catalytic activity, yielding over 99% ethylene conversion with non-Schulz-Flory type distribution of the generated hydrocarbons (C8>C6>C4>C10+) and high stability at 200°C and 10bar at a weight hourly space velocity of 0.375h−1 for 60h. Co-oligomerization of the as-synthesized liquid oligomer mixture over Amberlyst-35 ion-exchange resin under the optimized reaction conditions (5wt% catalyst loading, 100°C, 30bar N2, and 24h of reaction time) generated greater than 98% C5+ liquid product, where the C10+ olefins constituted about 42%. The catalytic activity of the Amberlyst-35 catalyst used was almost identical to that of the fresh catalyst after washing with n-heptane and drying.

Anodic Activity of Pt and PtRu Catalysts on Ta-Doped SnO2 Supports for Direct-Fuel Fuel Cells Using a New Energy Carrier

Polymer electrolyte fuel cells (PEFCs) directly fueled liquid fuels are suitable power source for portable energy applications. Liquid alcohol fuels such as methanol and ethanol are attractive energy carriers with good energy density and low cost. However, the problems of their low flash points (below room temperature) and/or toxicity should be overcome for the safe application of alcohol-fueled PEFCs. The liquid oligomers of poly oxymethylene dimethyl ether (POMMn: CH3-O-(CH2-O)n-CH3, n = 3~8) have been proposed as alternative fuels, due to their advantages, including their higher energy density, lower toxicity and higher flash point1-3). In this study, we synthesized Pt and PtRu catalysts supported on Ta-SnO2 (Pt/Ta-SnO2, PtRu/Ta-SnO2) for the direct oxidation of POMM and evaluated their performance in a PEFC. The Ta-SnO2 support4) was synthesized by the flame spray synthesis method. The oxide supports obtained were nanometer-sized particles with a carbon-like fused-aggregate structure. Pt and PtRu catalysts were loaded on the Ta-SnO2 by the colloidal method. The Pt/Ta-SnO2 (Pt loading amount, 14.0 wt%; particle size, 6.3 nm) and PtRu/Ta-SnO2 (Pt/Ru loading amount, 6.3/3.5 wt%; particle size, 2.2 nm) were obtained after heat treatment. The Pt and PtRu particles were highly dispersed on the Ta-SnO2 support. As shown in the high-angle annular dark-field STEM (HAADF-STEM) image and STEM-EDX line profile, Sn metal diffused into the Pt catalysts with the sintering process. X-ray photoemission spectroscopic (XPS) Sn 3d5/2 spectra for each catalyst indicated that part of the Sn was converted from Sn4+ to Sn0. We concluded that the catalysts formed binary Pt-Sn and ternary Pt-Ru-Sn alloys during the sintering procedure (Fig. 1). The onset potential for POMM2 oxidation on PtRu/Ta-SnO2, which was measured by a half-cell with a rotating disk electrode (RDE), was 0.3 V less positive than that of a commercial Pt2Ru3/CB catalyst (Fig. 2). The mass activity for POMM2 oxidation of PtRu/Ta-SnO2 at 0.5 V was also 3.5 times higher than that for a commercial Pt2Ru3/CB catalyst. The anodic activity of Pt/Ta-SnO2 was also higher than that of the commercial catalyst, by a factor of 2. The electrochemical performances of these anode catalysts were also evaluated by the use of membrane-electrode assemblies (MEAs, NRE117 membrane, commercial Pt/CB(TEC10E50E) 0.5 ± 0.025 mgPt cm2 cathode, Pt/Ta-SnO2 or PtRu/Ta-SnO2 0.25 or 0.27 mgPt cm2 anode, Fig. 3). The current densities of the MEAs using the Pt/Ta-SnO2 and PtRu/Ta-SnO2 catalysts as the anodes and Pt/CB as the cathode (POMM2 simulated fuel, O2 oxidant, 80oC operation temperature) were more than 10 times higher than that using the commercial Pt2Ru3/CB anode. The current density at 0.6 V for formaldehyde fuel supplied to an MEA applying the Pt/Ta-SnO2anode was 15 times higher than that for the commercial anode, even though the performance for methanol remained at the same level. We consider that the Sn on the surface of the Pt catalyst may suppress CO poisoning by weakening the adsorption strength of CO formed during the fuel oxidation processes, even at such low potentials as 0.2 to 0.4 V, and directly accelerate the oxidation of carbon monoxide at more positive potentials by a bifunctional mechanism, similar to that for Pt-Ru catalysts. Acknowledgements This work was partially supported by funds for the A-STEP project from the Japan Science and Technology Agency (JST), JSPS KAKENHI (B24350093) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and the SPer-FC project from the New Energy and Industrial Technology Development Organization (NEDO) of Japan. References 1) D. Devaux, H. Yano, H. Uchida, J.L. Dubois, M. Watanabe, Electrochim. Acta 56 (2011) 1460. 2) S. Baranton, H. Uchida, D.A. Tryk, J.L. Dubois, M. Watanabe, Electrochim. Acta 108 (2013) 350. 3) K. Kakinuma, I.T. Kim, Y. Senoo, H. Yano, M. Watanabe, and M. Uchida, ACS Appl. Mater. Interfaces, 6 (2014) 22138. 4) Y. Senoo, K. Taniguchi, K. Kakinuma, M. Uchida, H. Uchida, S. Deki, and M. Watanabe, Electrochem. Commun., 51 (2015) 37. Figure 1

Cross-linking of titanosiloxane oligomers and properties of materials with vulcanized titanosiloxane coatings

The structuring of the liquid titansiloxan oligomer at higher temperatures is studied. The properties of cover materials were investigated. It is shown that the materials have a high fire resistance and physical and mechanical properties compared to materials with vulcanized cover on the base of liquid siloxane rubbers.