Viscoelastic and Mechanical Behavior of Hydrophobically Modified Hydrogels
Viscoelastic and Mechanical Behavior of Hydrophobically Modified Hydrogels
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DOI：
10.1021/ma202130u
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发表时间：
2011-12-13
期刊：
影响因子：
5.5
通讯作者：
Weiss, R. A.
中科院分区：
文献类型：
--
作者：
Hao, Jinkun;Weiss, R. A.
通过流变学和静态拉伸实验研究了N，N-二甲基丙烯酰胺(DMA)和N-(N-乙基全氟辛基磺酰胺基)丙烯酸乙酯(FOSA)在不同FOSA浓度下合成的物理交联共聚物水凝胶的粘弹性和力学行为。FOSA部分在水环境中的强烈疏水缔合产生了提供物理交联的核壳纳米结构域。这些PDMA-FOSA水凝胶表现出优异的机械性能，包括类似于130-190 kPa的模数、1000-1600%的断裂伸长率以及类似于500 kpa的拉伸强度，具体取决于FOSA的浓度。物理凝胶比类似的化学凝胶更粘性，在分散应力方面要有效得多。后一种特性产生了相对较高的拉伸韧性，类似于4-6兆帕，因为可逆、疏水的交联物提供了额外的能量耗散机制。PDMA-FOSA水凝胶表现出强烈的温度依赖性的特殊动力学行为。在25℃时，水凝胶具有很高的弹性，但随着温度的升高，其粘性行为增加，并且随着材料的流变特性从粘弹性固体转变为粘弹性液体，在55℃时发生动态模量值(即G‘’>；G‘)的交叉。这种行为是物理交联链结构的物理性质和疏水缔合的动态性质的结果，这些性质受组成、温度和时间的影响。
The viscoelastic and mechanical behaviors of physically cross-linked copolymer hydrogels synthesized from N,N-dimethylacrylamide (DMA) and 2-(N-ethylperfluorooctane sulfonamido)ethyl acrylate (FOSA) with varying FOSA concentration were studied by rheological and static tensile tests. The strong hydrophobic association of the FOSA moieties in an aqueous environment produced core shell nanodomains that provided the physical cross-links. These PDMA-FOSA hydrogels exhibited excellent mechanical properties, including a modulus of similar to 130-190 kPa, elongation at break of 1000-1600%, and similar to 500 kPa tensile strength, depending on the FOSA concentration. The physical gels were more viscous than comparable chemical gels and were much more efficient at dissipating stress. The latter characteristic produced relatively high tensile toughness, similar to 4-6 MPa, because of the extra energy dissipation mechanism provided by the reversible, hydrophobic cross-links. The PDMA-FOSA hydrogel exhibited peculiar dynamic behavior which was greatly dependent on temperature. At 25 degrees C, the hydrogel was highly elastic, but as the temperature increased, its viscous behavior increased and a crossover of the dynamic moduli (i.e., G '' > G') occurred at 55 degrees C, as the rheological characteristics of the material went from a viscoelastic solid to a viscoelastic liquid. That behavior is a consequence of the physical nature of the structure of the physical cross-links and the dynamic nature of hydrophobic associations, which are influenced by composition, temperature, and time.