The effects of ions on the structures and properties of poly(vinyl alcohol) films were systematically studied using various metal salts. Although cations play an important role, the data obtained in this study demonstrated that the strong ion–dipole interactions between anions and poly(vinyl alcohol) chains also have a significant impact on crystallinity and glass transition temperature. For the first time, the study revealed that the impact of the added salts follows the Hofmeister series. Investigations of various bromine salt cations revealed that Li+ is more effective at disrupting the water structure than either Na+ or K+. Further experiments using lithium salts with various anion species verified that lithium salts play an important role in determining the crystallinity and hydrogen bonding within aqueous poly(vinyl alcohol) and therefore affect the dynamic mechanical properties of films. This phenomenon clearly follows the order LiClO4 > LiI > LiBr > LiNO3 > LiCl, which corresponds to the Hofmeister series. The salt addition affects the structure and properties of poly(vinyl alcohol) films as it reduces the hydrogen bonding in PVA chains and decreases the crystallinity. Consequently, the Tg shifts to low temperatures, and the modulus beyond Tg decreases markedly. This study confirmed that the impact of bromine salts on the structure and properties followed the order of Hofmeister series, i.e., Li+ > Na+ > K+. Although cations play an important role, the data obtained also demonstrated that the strong ion–dipole interactions between anions and PVA chains have a significant impact on the crystallinity and Tg.

中文翻译：

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Hofmeister系列在含金属盐的聚乙烯醇薄膜结构和性能中的应用

使用各种金属盐系统地研究了离子对聚乙烯醇薄膜结构和性能的影响。尽管阳离子起着重要作用，但本研究中获得的数据表明，阴离子和聚乙烯醇链之间的强离子-偶极相互作用也对结晶度和玻璃化转变温度有显着影响。该研究首次揭示了添加盐的影响遵循 Hofmeister 系列。对各种溴盐阳离子的研究表明，Li+ 在破坏水结构方面比 Na+ 或 K+ 更有效。使用具有各种阴离子种类的锂盐的进一步实验证实，锂盐在确定水性聚乙烯醇中的结晶度和氢键方面起着重要作用，因此会影响薄膜的动态机械性能。这种现象显然遵循 LiClO4 > LiI > LiBr > LiNO3 > LiCl 的顺序，这对应于 Hofmeister 系列。添加盐会影响聚乙烯醇薄膜的结构和性能，因为它会减少 PVA 链中的氢键并降低结晶度。因此，Tg 向低温移动，超过 Tg 的模量显着降低。本研究证实溴盐对结构和性质的影响遵循Hofmeister系列的顺序，即Li+>Na+>K+。