Structural investigations of a neutralized polyelectrolyte gel and an associating neutral hydrogel
Structural investigations of a neutralized polyelectrolyte gel and an associating neutral hydrogel
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DOI：
10.1016/j.polymer.2005.02.054
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发表时间：
2005-05-26
期刊：
影响因子：
4.6
通讯作者：
Geissler, E
中科院分区：
文献类型：
--
作者：
Horkay, F;Basser, PJ;Geissler, E
小角中子散射（SANS）测量用于区分两种不同类型的水凝胶中的聚合物链的局部组织。在中性聚乙烯醇凝胶中，氢键引起叠加在底层化学交联网络上的长程结构扰动，从而在散射矢量q的小值处产生过量散射。这种次级超结构导致弹性模量的增加。在这些凝胶中的热波动散射的强度可以描述由Ornstein-Zernike线形，是一致的，从宏观渗透和力学observations. Strong-charged聚丙烯酸酯水凝胶推导出的渗透模量，然而，显示出质的不同的散射响应。在低q下，观察到分形表面的幂律行为。在中间q处，另一种渗透来源的组分是可见的，其随q（-1）变化，这表明二价阳离子的存在有利于网络链的线性排列。从SANS推导出的热波动的估计和独立的渗透观测结果之间的可接受的协议。© 2005爱思唯尔有限公司版权所有。
Small angle neutron scattering (SANS) measurements are used to differentiate the local organization of the polymer chains in two different classes of hydrogel. In neutral polyvinyl alcohol gels, hydrogen bonding gives rise to long range structural perturbations that are superimposed on the underlying chemically cross-linked network, thus producing excess scattering at small values of the scattering vector q. This secondary superstructure causes an increase in the elastic modulus. The intensity scattered by the thermal fluctuations in these gels can be described by an Ornstein-Zernike lineshape and is consistent with the osmotic modulus deduced from macroscopic osmotic and mechanical observations.Strongly charged polyacrylate hydrogels, however, display a qualitatively different scattering response. At low q a power law behavior is observed characteristic of a fractal surface. At intermediate q another component of osmotic origin is visible, which varies as q(-1), which indicates that the presence of divalent cations favors linear alignment of the network chains. Acceptable agreement is found between the estimate of the thermal fluctuations deduced from SANS and the results derived from independent osmotic observations. © 2005 Elsevier Ltd. All rights reserved.