A large number of studies have confirmed that encapsulating an insulating shell on the surface of high-permittivity nanofillers can effectively improve the energy storage performance of polymer-based dielectric nanocomposites. Regrettably,...
Polymeric dielectrics with high-temperature resilience are of critical importance in developing advanced electrostatic capacitors. Poly-(p-phenylene benzobisoxazole) (PBO) is a polymer with excellent thermal stability. However, the poor processability and low...
Polyimide (PI) and its derivative polyetherimide (PEI)
have been
widely investigated as promising candidates for dielectric energy
storage due to their excellent intrinsic features. However, most of
the current research for PI- or PEI-based dielectric nanocomposites
only focuses on a certain polar group contained in a dianhydride monomer,
while there are very few studies on exploring the effect of a series
of polar groups derived from various dianhydride monomers on the dielectric
properties of nanocomposites. To fill this gap, we herein fabricated
and investigated a series of novel hyperbranched polyimides grafted
on barium titanate nanoparticles (HBPI@BT) using different dianhydride
monomers and their nanocomposites with the PEI matrix. The results
showed that sophisticated hyperbranched structures effectively alleviated
the incompatibility between fillers and the matrix, thus significantly
improving the bonding energy of nanocomposites, especially for HBPI-S@BT/PEI
(797.7 kJ/mol). The U
d of HBPI-S@BT/PEI
reached 8.38 J/cm3, which is 3.3 times higher than that
of pure PEI. The HBPI-F@BT/PEI nanocomposites achieved high breakdown
strength (∼500 MV/m) and low dielectric loss (0.008) simultaneously.
The dielectric constants of HBPI@BT/PEI nanocomposites remained at
a stable level from 25 to 150 °C. This work provides us promising
hyperbranched structured materials for potentially advanced dielectric
applications such as field effect transistors.
In order to make up for the lack of washing fastness and chlorinated water fastness of nylon dyed with acid dyes, an aminosiloxane modified cationic waterborne polyurethane (KWPU) with the ability to reversibly adsorb chloride ions was synthesized. N‐methyldiethanolamine and ethylenediamine was used as chain extender. N‐aminoethyl‐γ‐aminopropyltrimethoxysilane was used to block the remaining isocyanate groups and provide secondary amine groups for reversible adsorption of chloride ions. The structure of KWPU was characterized by Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), 1H NMR, and differential scanning calorimetry (DSC). Particle size and zeta potential were tested to evaluate the emulsion stability. The research results showed that when the N‐methyl diethanolamine content was 14%, the water absorption rate of KWPU film was 82.1%, and when the KH‐792 content was 6%, the water absorption rate of KWPU was 34.8%. The addition of siloxane can significantly improve the thermal resistance of the KWPU film. The color fastness of the dyed nylon fabric treated with KWPU emulsion was significantly improved, the rubbing fastness was improved by 0.5 or 1 grade, the washing fastness was improved by 1 grade, and the fastness to chlorinated water was improved by 1.5 or 2 grade.
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