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Water and the Glass Transition Temperature in a Polyelectrolyte Complex
ACS Macro Letters ( IF 5.1 ) Pub Date : 2017-09-22 00:00:00 , DOI: 10.1021/acsmacrolett.7b00668
Jingcheng Fu 1 , Rachel L Abbett 1 , Hadi M Fares 1 , Joseph B Schlenoff 1
Affiliation  

Hydrated polyelectrolyte complexes, H-PECs, have recently started attracting renewed interest as a class of highly solvated/plasticized blends. H-PECs are observed to undergo a transition in mechanical properties close to room temperature. Whether this is a true glass transition has been questioned recently: the material has an unusually low modulus in the “glassy” state and molecular dynamics simulations have suggested temperature-induced dehydration and water structure changes are responsible for the transition. Using in situ infrared spectroscopic methods on thin films of a widely studied H-PEC we find no definitive evidence for changes in the hydration state of functional groups, the water content, or water structure on passing through Tg for stoichiometric and nonstoichiometric H-PECs. These complexes represent a promising platform for fundamental studies of the glass transition, since the coupling between chains can be modified by “doping” the material with salt, which breaks ion pairing cross-links. The Fox equation was used to estimate Tgs for paired and unpaired oppositely charged repeat units.

中文翻译:

聚电解质复合物中的水和玻璃化转变温度

水合聚电解质复合物 H-PEC 作为一类高度溶剂化/增塑的共混物,最近开始重新引起人们的兴趣。观察到 H-PEC 在接近室温时会发生机械性能的转变。这是否是真正的玻璃化转变最近受到质疑:该材料在“玻璃态”状态下具有异常低的模量,分子动力学模拟表明温度诱导的脱水和水结构变化是造成转变的原因。在广泛研究的 H-PEC 薄膜上使用原位红外光谱方法,我们没有发现通过T g时官能团的水合状态、水含量或水结构发生变化的确切证据用于化学计量和非化学计量 H-PEC。这些配合物为玻璃化转变的基础研究提供了一个很有前景的平台,因为可以通过用盐“掺杂”材料来改变链之间的耦合,从而破坏离子配对交联。Fox 方程用于估计成对和未成对的带相反电荷的重复单元的T g s。
更新日期:2017-09-22
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