二胺
单体
高分子化学
化学
蒸发
聚脲
化学计量学
电介质
基质(水族馆)
材料科学
有机化学
聚合物
聚氨酯
物理
海洋学
光电子学
热力学
地质学
作者
Xian–Shan Wang,Yoshikazu Takahashi,Masayuki Iijima,Eiichi Fukada
摘要
Four different kinds of aromatic polyurea were synthesized by vapor deposition of monomers. As a diisocyanate, [4,4 ′ -diphenyl methane diisocyanate] (MDI) was used. As a diamine, [4,4 ′ -diamino diphenyl methane] (MDA), [4,4 ′ -diamino-3,3 ′ -dimethyl diphenyl methane] (MeMDA), [4,4 ′ -diamino diphenyl ether] (ODA), and [4,4 ′ -diamino diphenyl sulfide] (SDA) were used. Poled thin films of P(MDA/MDI), P(MeMDA/MDI), P(ODA/MDI), and P(SDA/MDI) exhibited piezoelectric activity which remained up to almost 200° C. The stable value of the piezoelectric constant for P(ODA/MDI) was 26 mC/m 2 . The piezoelectric constant plotted against the evaporation temperature of MDI showed a maximum, where the stoichiometrically balanced composition of MDI and diamine monomer was obtained. The curve was sharp for P(MDA/MDI), but broad for P(ODA/MDI) and other polyureas. It was suggested that the high probability of production of balanced oligomers might be due to the longer time of residence of ODA molecules on the substrate.
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