Determination of residual stresses in adhesive materials based on epoxy oligomers

A method for calculating residual stresses in the adhesive layer is reported and results obtained are compared with experimental data. Theoretical calculations are performed under the assumptions that epoxy adhesive is an elastic material that obeys Hooke’s law. Residual stresses are measured by the console method.     

Modification of adhesive materials based on epoxy oligomers with fluorinated organic compounds

N-Containing perfluoropentanoic acid derivatives were used as modifying additives to commercial epoxy resins. As shown by differential thermal analysis, the fluorinated organic derivatives exhibit catalytic activity in curing of epoxy resins. The following characteristics of the adhesive compounds in the cured state were determined: degree of swelling, gel fraction content, ultimate shear strength of the adhesive joint, adhesion to low-carbon St.3 steel and AMg-6 aluminum-magnesium alloy, and corrosion-protective properties with respect to these materials.     

Polymeric electrolytes based on vinylpyridines

Homopolymers of 4-vinylpyridine and 2-methyl-5-vinylpyridine and copolymers of 2-methyl-5-vinylpyridine with vinyl chloride and vinyl acetate were prepared by radical copolymerization. Organo-inorganic composites were prepared by hydrolytic polycondensation of the copolymers obtained and tetraethoxysilane. From solutions of the (co)polymers and composites, films were prepared by casting, and their protonic conductivity was determined.     

Information media based on electron-donor oligomers

Routes for designing hole-conducting organic polymers for use in photoelectric solar-energy converters and light emitters and primarily for recording, storage, and processing of optical information are considered. New carbazole-containing radially tetrasubstituted silanes and germanes are described. It is shown that the information characteristics of holographic recording media based on oligomer compositions substantially depend on the shapes of the oligomer macromolecules.     

Polymeric materials for water-lubricated plain bearings

Results of tribological studies of modern polymeric materials (thermoplastics, thermosetting materials, composites) used to fabricate water-lubricated bearings are considered. Particular attention is given to carbon-fiber-reinforced plastics modified with powdered metals, fullerene-containing additives, and carbon nanotubes.     

Polymeric materials for solar water purification

Solar-based desalination or water purification is regarded as one of the promising solutions to global water scarcity as the only energy input is abundant and sustainable solar light. Interfacial solar vapor generation (SVG), which converts natural sunlight into clean water vapor, has attracted extensive research interests due to its high-energy utilization efficiency and simple implementation. With tunable molecular structures and tailorable physical properties, polymers have demonstrated great potential as candidate materials for solar evaporators. In this review, we summarize the recent progress on polymer materials for solar-powered water purification. First, we present functional polymers with highly tunable molecular composition and morphology as high-efficiency solar absorbers. Next, the recent development of various polymeric materials and structural engineering strategies for adequate water supply and efficient thermal management are discussed, along with their excellent desalination and purification performance. Last, we outline the challenges and future directions on the further development of polymer materials for solar water purification technologies.     

Electronic structure and properties of some oligomers based on fluorinated 1H-phospholes: n- versus p-type materials

A series of oligothiophenes and novel oligophospholes, consisting of fluorinated and perfluoroarene-substituted structures, were investigated using density functional theory (DFT) methods. The study focused on the geometrical structures and electronic properties. The degree of π-conjugation in the neutral oligomers was probed by different approaches including analysis of predicted Raman spectra. The character of the charge carrier of the new substituted oligomers, either electron (n-type doping) or hole (p-type doping) transport, was predicted by comparing their properties, including the frontier orbital HOMO and LUMO, excitation, and reorganization energies, with those of their non-substituted parent oligomers. The quantum chemical DFT results are consistent with available experimental data on the oligothiophenes for both geometries and conductivity properties. The results strongly suggest that an effective way of designing new materials with n-type conductivity is to introduce electron-withdrawing groups into the oligomer backbone. Calculated results were subsequently obtained for oligomers based on 1H-phospholes, which are predicted to have potentially useful properties as novel semiconductor materials.     

Macrospirocyclic oligomers based on carbazole and fluorene

Monodisperse macrospirocyclic oligomers were prepared using self-condensation of the Friedel-Crafts reaction. Through the C-9s of the central fluorene units of four surrounding oligofluorenes, four carbazole units are connected in a series to form a macrocyclic core. These rodlike oligofluorenes form a rigid three-dimensional structure, affording the resulting macrocyclics a high steric hindrance for close interchain packing.     

Epoxy oligomers based on eugenol cyclotriphosphazene derivatives

Oligomers of hexakis(4-allyl-2-methoxyphenoxy)cyclotriphosphazene have been synthesized and their molecular structure studied by X-ray and NMR analysis. The nonplanar character of a phosphazene cycle is established, and the bond lengths P-N and valence angles N-P-N are shown to change in narrow ranges (1.5771–1.5894 Å and 117.80°–118.37°, respectively). During epoxidation of hexakis(4-allyl-2-methoxyphenoxy)cyclotriphosphazene by m-chloroperbenzoic acid or peracetic acid, in addition to hexaepoxy derivatives, the corresponding dimer is formed due to partial intermolecular interaction of epoxy groups.     

Oligonucleotide-directed assembly of materials: defined oligomers.

A nano-architectural system that has high variability while maintaining component specificity is described. Tetraphenylcyclobutadiene(cyclopentadienyl)cobalt complexes and phenyleneethynylene trimers were synthesized and subsequently modified with oligonucleotides utilizing standard phosphoramidite chemistry. The resulting oligonucleotide modified organics (OMOs) were characterized by UV-vis spectroscopy, fluorescence spectroscopy, and phosphate analysis. Hybridization of these OMOs resulted in a series of self-assembled oligomeric hybrids of varying length and topology. These hybrids were characterized by melting temperature, polyacrylamide gel electrophoresis, and fluorescence spectroscopy. This model system demonstrates the power of DNA to self-assemble modules of interest-independent of the module itself.     

Polymeric positive-temperature-coefficient materials: dynamic curing effect

The object of this work was to prepare high-density polyethylene (HDPE)/ethylene–propylene–diene terpolymer (EPDM)/conductive carbon black (CB) composites by dynamic curing and to characterize the positive-temperature-coefficient (PTC) performances of the composites.EPDM and dicumyl peroxide were preblended in a research mill. The roll-milled strands were blended with HDPE and CB in a Haake mixer. The sheet resistivity and morphology of the HDPE/EPDM/CB composites with or without the dynamic curing process were investigated. It was concluded that the dynamically cured blends exhibit better PTC performance than the simple blends without dynamic curing. The effects of shear intensity and dicumyl peroxide content during the dynamic curing process were discussed for the PTC characteristics of the HDPE/EPDM/CB composites.     

Polymeric materials with grafted luminescent organosiloxane coatings

A procedure was developed for preparing polymeric materials with grafted luminescence organosiloxane coatings containing conjugates of rare-earth elements with various color spectra.     

Novel thermoresponsive water-soluble oligomers based on amphiphilic calixresorcinarenes

Novel water-soluble thermoresponsive oligomers TO1 and TO2 were obtained by reaction of amidoamine tetramethylcalixresorcinarenes (C1) and tetrapentylcalixresorcinarenes (C5) with ethylene glycol diglycidyl ether. The compounds were characterised by ¹H and FT-PGSE NMR, FTIR, static light scattering and elemental analysis. The thermoresponsive properties of oligomers were investigated by spectrophotometry, DLS, FT-PGSE NMR and TEM. The cloud points of oligomers (43 °C for TO1 (5 mg/ml) and 41 °C for TO2 (1.2 mg/ml), respectively) were determined. The influence of salts effect on TO2 cloud points was investigated. The binding of anti-inflammatory drug naproxen (Nap) at 20 °C by TO1 and TO2 and its partial release at cloud points of oligomers in aqueous solution are observed using fluorescence and FT-PGSE NMR methods. New example of creating of thermoresponsive macrocyclic systems on the basis of amidoamine calixresorcinarenes with possibility of substrate binding and release under the influence of termo-stimuli in an aqueous solution was shown.     

Polymeric waveguides based on photopolymerizing methacrylate compositions

Contact photolithography was used to fabricate three-layer polymeric waveguide structures with transverse dimensions of 50 × 90 μm on the basis of two photopolymerizing methacrylate compositions with different refractive indices. The optical loss on the wavelength of 632.8 nm was 0.37 ± 0.14 dB cm^?1. This loss is mostly due to the light scattering by the material of the waveguide layer produced by bulk polymerization.     

Polymeric materials for lithium‐ion cells

Lithium‐ion (Li‐ion) cells have gained considerable attention in recent years as a power source for various applications owing to their high voltage, high energy density, low self‐discharge, and excellent cycle life. Polymeric materials play a pivotal role in the processing, performance, and safety of Li‐ion cells. The polymeric materials used in Li‐ion cells include: binder for electrode processing, separator, electrolyte, and electrode active material. Active research is being pursued in all of these areas to improve the energy density, power density, cycle life, and safety of Li‐ion cells. This review article gives an overview of the various polymeric materials used in Li‐ion cells and the recent advances in these materials. Copyright © 2017 John Wiley & Sons, Ltd.     

A method of quantitative evaluation of the content of free furfural in glued wood materials based on furan oligomers

A technique and experimental results of the evaluation of free furfural content in glued wood materials produced with the use of furan oligomers are presented.     

Synthesis of polyurethane acrylate oligomers based on polybutadiene polyol

Polyurethane acrylate oligomers (PUA) were prepared by a competitive reaction of 4,4′-dicyclohexyl methane diisocyanate (H₁₂MDI) with hydroxy terminated polybutadiene (HTPB) and hydroxyethylacrylate (HEA). Kinetic models were established for noncatalytic and catalytic systems, and the reaction constants were calculated using a numerical method. The evolution of the noncatalyzed and catalyzed reactions were analyzed, respectively, by SEC and FTIR. Comparing the reactivities of HTPB and HEA, as well as other small molar mass model alcohols, the HTPB showed the higher reactivity. HTPB is 700 times more reactive than HEA at 80°C. This high reactivity was analyzed as a result of lower concentration of hydrogen bonds in bulk HTPB. The activation energy of the noncatalyzed and catalyzed reactions were found to be, respectively, 56.98 and 45.16 KJ/mol. The structures of the PUA synthetized in one-step or two-step process were analyzed and discussed using a gelation model and the kinetic data obtained. © 1996 John Wiley & Sons, Inc.     

Halogenated hydroxy-aryloxy phosphazenes and epoxy oligomers based on them

By partial substitution of the chlorine atoms in hexachlorocyclotriphosphazene for halophenols and subsequent reaction of the resulting halogenated phenoxy phosphazene and 2,2-di(4-hydroxyphenyl)propane monophenolate hydtoxy-aryloxy phosphazenes were synthesized with a molecular weight of 1100–1400 g mol^?1. Epoxide oligomers (epoxy number of 6–8%), which are cured with the formation of non-combustible compositions [PV-0 class of resistance to combustion according to State Standard (GOST 28157-89)], were obtained by reaction of these compounds with epichlorohydrin. Introduction of 5–50 wt% halogenated epoxyphophazene oligomers in industrial resin ED-20 can significantly improve the flame resistance of compositions based on these compounds.     

Polymeric composites based on alicyclic polyimide and polyaniline

Specific features of modification of an alicyclic polyimide with polyaniline were examined. The thus obtained new polymeric composites exhibit better capability for silver plating.     

Polymeric materials based on main group elements: the recent development of ambient temperature and controlled routes to polyphosphazenes

This Perspective discusses the development of new routes to polyphosphazenes, [R(2)P[double bond, length as m-dash]N](n), that occur at ambient temperature and, in some cases, allow molecular weight control and access to narrow molecular weight distributions and block copolymers. For example, the room temperature silyl-carborane initiated ring-opening polymerisation of (NPCl(2))(3) is described together with chain growth condensation polymerisations of phosphoranimines Cl(3)P[double bond, length as m-dash]NSiMe(3) and BrMePhP[double bond, length as m-dash]NSiMe(3). Recent works on donor-stabilised cationic phosphoranimines are also discussed.