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非遍历光散射
巯基-烯聚合水凝胶的非均质性【tu-clausthal】

阅读:

5

发布:

2013-12-25

作者:

德国克劳斯塔尔理工大学物理化学研究所(Institute of Physical Chemistry, Clausthal University of Technology)的Svenja Grube和Wilhelm Oppermann通过巯基-烯聚合合成了水凝胶,并用弹性测量表征了该样品的宏观性能,用动态光散射表征了该样品的微观性能(尤其是非均质性)。研究者对自由基链式生长交联共聚制备的聚丙烯酰胺(PAAm)水凝胶进行了相同测试,并进行了比较。力学测试结果证明,对于这两种类型凝胶,浓度不同,网格缺陷的程度变化很大,而在特定浓度下所观察到的宏观性能非常相近。但在制备过程中测量时,反应凝胶非均质性的静态分数明显取决于所研究的网格类型。与PAAm凝胶不同的是,大多数巯基-烯凝胶看起来是均匀的。在平衡溶胀状态下,情况反转,不管反应类型或合成过程中使用的浓度如何,所有凝胶都表现出很高且几乎相同的静态散射强度分数。这些观察结果暗示凝胶网格缺陷与均质性之间没有明显的相关性,制备状态下交联反应的类型会影响浓度的非均质性,但并不控制网格密度的非均质性,后者在凝胶溶胀时是可以观察到的。

相关工作以Inhomogeneity in Hydrogels Synthesized by Thiol−Ene Polymerization为题,发表在Macromolecules, 2013 46 (5), 1948-1955上。

本文通讯作者为杜克劳斯塔尔大学教授Wilhelm Oppermann博士。Oppermann教授曾在德国纺织和纤维研究所工作,并曾担任斯图加特大学化学与纺织化学研究所领导,2003年他成为杜克劳斯塔尔大学物理化学(C4)教授。

英文题目:

Inhomogeneity in Hydrogels Synthesized by Thiol−Ene Polymerization

出版源:

Macromolecules, 2013 46 (5), 1948-1955

DOI: 

https://doi.org/10.1021/ma302520p

作者:

Svenja Grube and Wilhelm Oppermann*

Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, D-38678 Clausthal-Zellerfeld, Germany

摘要:

Hydrogels synthesized via thiol–ene polymerization were characterized with respect to their macroscopic properties via elasticity measurements and to their microscopic properties, in particular inhomogeneity, by dynamic light scattering. For comparison, identical studies were made on polyacrylamide (PAAm) hydrogels prepared by free-radical chain-growth cross-linking copolymerization. Mechanical measurements prove that for both types of gels the degree of network imperfections is widely varied by varying concentration, while the macroscopic properties observed at particular concentrations are very similar. However, the fraction of static scattering which is a measure of gel inhomogeneity depends significantly on the type of network studied when the measurement is performed in the state of preparation. The majority of the thiol–ene gels appear homogeneous, contrary to the PAAm gels. The situation is completely different in the equilibrium swollen state, where all gels exhibit extremely high and almost identical fractions of static scattering intensity, irrespective of the type of reaction or the concentration employed in their synthesis. These observations imply that (i) there is no clear correlation between network imperfections and homogeneity and (ii) the type of cross-linking reaction controls the concentration inhomogeneity in the state of preparation but not (iii) the inhomogeneity of network density. The latter is seen when the gels are swollen.

关键词:

casein micelles, sodium chloride, concentrated milk, rennet gelation