Role of microscopic phase separation in gelation of aqueous gelatin solutions
Role of microscopic phase separation in gelation of aqueous gelatin solutions
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DOI：
10.1039/c3sm52542b
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发表时间：
2014-01-01
期刊：
影响因子：
3.4
通讯作者：
Basletic, Mario
中科院分区：
文献类型：
--
作者：
Pelc, Damjan;Marion, Sanjin;Basletic, Mario
使用一个独特的自制的细胞的导电液体样品的四接触阻抗谱，我们建立了两个低频电导弛豫在明胶的水溶液中，在液体和凝胶状态的存在。与扩散测量脉冲场梯度NMR，和圆二色光谱的比较，表明更快的弛豫过程是由于明胶大分子的自扩散。这种单分子扩散对样品的宏观状态大多不敏感，这意味着我们将明胶分子清楚地分离成自由相和网络结合相。自扩散的标度关系表明，凝胶化过程是不是一个degradative现象，但所造成的聚集成一个系统的跨越纤维网络的三重螺旋。
Using a unique home-made cell for four-contact impedance spectroscopy of conductive liquid samples, we establish the existence of two low frequency conductivity relaxations in aqueous solutions of gelatin, in both liquid and gel states. A comparison with diffusion measurements using pulsed field gradient NMR, and circular dichroism spectroscopy, shows that the faster relaxation process is due to gelatin macromolecule self-diffusion. This single molecule diffusion is mostly insensitive to the macroscopic state of the sample, implying that we have a clear separation of gelatin molecules into a free and network-bound phase. Scaling relationships for the self-diffusion indicate that the gelation process is not a percolative phenomenon, but is caused by aggregation of triple helices into a system-spanning fibre network.