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Epoxy-capped polyhedral oligomeric silsesquioxane (EP-POSS) is performed to modify bisphenol A cyanate ester (BADCy) to regulate its dielectric constant and thermal resistance. EP-POSS can be incorporated in the cross-linked network of BADCy via covalent bonds, which catalyzes BADCy self-polymerization to decease the initial temperature of forming triazine rings. EP-POSS is distributed in the BADCy matrix uniformly and there is no aggregation and phase separation between EP-POSS and BADCy matrix at a micrometer scale. The dielectric constant values of EP-POSS/BADCy are decreased with the addition of EP-POSS, but increased slightly when the mass fraction of the EP-POSS is more than 2 wt%. The thermal resistance of EP-POSS/BADCy is increased slightly with the addition of EP-POSS. [ABSTRACT FROM AUTHOR]

Quartz fibers (QFs) and two polyhedral oligomeric silsesquioxane (POSS) (epoxy-POSS and hydroxy-POSS) are performed to regulate the dielectric properties, heat resistance, and mechanical properties of cyanate ester (CE) resins. With the introduction of POSS, the dielectric constant and dielectric loss tangent values of the POSS/QFs/CE laminated composites are decreased obviously. The heat resistance properties and flexural strength values of the laminated composites are increased, but the interlaminar shear strength values of the laminated composites are decreased slightly. The EP-POSS/QFs/CE laminated composites have relatively better dielectric, heat resistance, and mechanical properties than those of HO-POSS/QFs/CE laminated composites. POLYM. COMPOS., 36:2017-2021, 2015. © 2014 Society of Plastics Engineer [ABSTRACT FROM AUTHOR]

A new series of liquid crystal (LC) monomers – not only contain a double bond but also contain an azo group – were designed and synthesised. The length of side groups in the LC monomers containing azobenzene ester varied from 1 to 2 methylene units, and the length of the substituted groups in the main chain varied from 1 to 3 methylene units. The molecular structures of the intermediates and target compounds were confirmed by Fourier transform infrared, ultraviolet and visible spectrum and nuclear magnetic resonance (NMR) spectroscopy. The thermal phase behaviour of the LC monomers was investigated by polar optical microscopy coupled with hot stage and differential scanning calorimetry (DSC). In this paper, the effect on the LC zone with the substituents were investigated, and with the increased methylene of main chain, the melting point and the phase transition temperature of the substance will be lowered and LC regions will be narrower. [ABSTRACT FROM AUTHOR]

The development of highly thermally conductive composites that combine visible light/infrared camouflage and information encryption has been endowed with great significance in facilitating the application of 5G communication technology in military fields. This work uses aramid nanofibers (ANF) as the matrix, hetero-structured silver nanowires@boron nitride nanosheets (AgNWs@BNNS) prepared by in situ growth as fillers, which are combined to fabricate sandwich structured thermally conductive and electrically insulating (BNNS/ANF)-(AgNWs@BNNS)-(BNNS/ANF) (denoted as BAB) composite films by "filtration self-assembly, air spraying, and hot-pressing" method. When the mass ratio of AgNWs@BNNS to BNNS is 1 : 1 and the total mass fraction is 50 wt %, BAB composite film has the maximum in-plane thermal conductivity coefficient (λ ∥ of 10.36 W/(m ⋅ K)), excellent electrical insulation (breakdown strength and volume resistivity of 41.5 kV/mm and 1.21×10 15  Ω ⋅ cm, respectively) and mechanical properties (tensile strength of 170.9 MPa). 50 wt % BAB composite film could efficiently reduce the equilibrium temperature of the central processing unit (CPU) working at full power, resulting in 7.0 °C lower than that of the CPU solely integrated with ANF directly. In addition, BAB composite film boasts adaptive visible light/infrared dual camouflage properties on cement roads and jungle environments, as well as the function of fast encryption of QR code information within 24 seconds., (© 2024 Wiley‐VCH GmbH.)