A series of novel aqueously soluble semi-aromatic (co)polyamides, poly[(ethylenedioxy)bis(ethylene) terephthalamide]-ranpoly[(ethylenedioxy)bis(ethylene) (2,5-dihydroxy-3,6-diallyl)terephthalamide] (CRPAOT-x), were prepared via the solid-state Claisen rearrangement reaction of poly[(ethylenedioxy)bis(ethylene) terephthalamide]-ran-poly[(ethylenedioxy)bis(ethylene) 2,5-bis(allyloxy)terephthalamide] (APAOT-x), where x (= 0, 13, 25, 50, 75, and 100) represents the molar fraction of allyloxy containing unit. APAOT-x was obtained through the interfacial copolymerization of terephthaloyl chloride, 2,5-bis(allyloxy)terephthaloyl chloride, and 2,2 0 -(ethylenedioxy)bis(ethylamine). The reaction conditions including reactant concentration, temperature, and solvent were optimized. The chemical structures of the target (co)polyamides and their precursors were characterized by proton nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared spectroscopies. The incorporation of hydrophilic (ethylenedioxy)bis(ethylene) units greatly improved the polymer solubility. CRPAOT-x dissolved not only in polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and N-methyl pyrrolidone but also in ammonia water. Due to the presence of hydroxyl groups and oxygen-rich aliphatic units, CRPAOT-x showed excellent affinity toward epoxy resins. The microbond test indicated that the aramid fibers sized by these dual-functional polymers exhibited remarkably enhanced interfacial shear strength in epoxy matrices.
In the Pd/Co/Pd trilayer with magnetic perpendicular anisotropy, it has been found that both the saturation magnetization MS and the coercivity HC demonstrate a drastic time-dependent decrease. The time-dependent effect has been observed to be strongly related to the Co layer thickness. When the Co layer is thinner, the drops of HC and MS become much faster with time. The observed time-dependent effect is attributed to absorption of gaseous elements (for example, hydrogen) during exposure of the sample to the air, which can induce the reduction in Pd-polarization.
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