AbstractWe investigated the effects of two metal salts, lithium trifluoromethanesulfonate (LiCF3SO3) and lithium bromide (LiBr), on the glass transition temperature (Tg) of poly(methyl methacrylate) (PMMA). Both LiCF3SO3 and LiBr greatly enhanced the Tg of PMMA under dry conditions. However, once the sample films were exposed to humidity, the PMMA containing LiCF3SO3 absorbed a large amount of water, which acts as a plasticizer. As a result, the Tg shifted to a lower temperature, which limits the utility of this polymer in industrial applications. In contrast, the Tg of PMMA containing LiBr was minimally affected by the absorption of water. This phenomenon can be explained by the ion–dipole interactions with the small number of dissociated lithium cations.Tg of PMMA was greatly enhanced by introducing ion–dipole interaction between lithium cations and carbonyl groups in PMMA as pseudo crosslinking points.

中文翻译：

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盐提高聚甲基丙烯酸甲酯的玻璃化转变温度

摘要我们研究了三氟甲磺酸锂 (LiCF3SO3) 和溴化锂 (LiBr) 这两种金属盐对聚甲基丙烯酸甲酯 (PMMA) 玻璃化转变温度 (Tg) 的影响。在干燥条件下，LiCF3SO3 和 LiBr 都大大提高了 PMMA 的 Tg。然而，一旦样品薄膜暴露在潮湿环境中，含有 LiCF3SO3 的 PMMA 就会吸收大量的水，起到增塑剂的作用。结果，Tg 转移到较低的温度，这限制了该聚合物在工业应用中的实用性。相比之下，含有溴化锂的 PMMA 的 Tg 受水吸收的影响最小。这种现象可以通过离子-偶极子与少量离解锂阳离子的相互作用来解释。