Influence of Nonstoichiometry on the Viscoelastic Properties of a Polyelectrolyte Complex
Influence of Nonstoichiometry on the Viscoelastic Properties of a Polyelectrolyte Complex
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DOI：
10.1021/acs.macromol.1c01154
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发表时间：
2021-09-02
期刊：
影响因子：
5.5
通讯作者：
Schlenoff, Joseph B.
中科院分区：
文献类型：
--
作者：
Chen, Yuhui;Yang, Mo;Schlenoff, Joseph B.
取决于诸如混合比、添加速度和顺序以及离子强度的条件，当带相反电荷的聚电解质的溶液混合时，所形成的双金属络合物（佩奇）的化学计量可以变化。事实上，在大多数情况下，一定程度的非化学计量是不可避免的，因为正电荷和负电荷的比例并不像一些早期工作中所认为的那样“锁定”在1：1。PEC的形态和力学性能取决于聚阳离子和聚阴离子之间的摩尔比。在这项工作中，聚（二烯丙基二甲基铵）和聚（苯乙烯磺酸盐），使佩奇与不同的化学计量。由于水含量增加引起的增塑效应，用一种过补偿的佩奇显示出具有较低的玻璃化转变温度和模量。此外，时间-温度叠加揭示了节段弛豫时间和化学计量之间的相关性。非化学计量的佩奇被证明具有升高的自由体积分数和降低的聚合物体积分数，这是它们的机械性能变化的原因。
Depending on conditions such as the mixing ratio, speed and order of addition, and ionic strength, when solutions of oppositely charged polyelectrolytes are mixed, the stoichiometry of the formed polyelectrolyte complexes (PECs) can vary. In fact, for most conditions, some degree of nonstoichiometry is inevitable because the ratios of positive and negative charges do not "lock" themselves to 1:1, as was believed in some early work. PEC morphologies and mechanical properties depend on the molar ratio between the polycation and polyanion. In this work, poly(diallyldimethylammonium) and poly(styrene sulfonate) were used to make PECs with varying stoichiometries. PECs that were overcompensated with one polyelectrolyte were shown to have lower glass transition temperatures and moduli due to the plasticizing effect caused by increased water content. In addition, time-temperature superposition revealed a correlation between segmental relaxation times and stoichiometry. Nonstoichiometric PECs were shown to have elevated fractional free volumes and decreased polymer volume fractions, which are responsible for changes in their mechanical properties.