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arXiv 1502.01500cond-mat.soft
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溶剂对用准弹性中子散射表征的物理凝胶稳定性的贡献

Solvent contribution to the stability of a physical gel characterized by quasi-elastic neutron scattering

Sylvie Spagnoli, Isabelle Morfin, Miguel A. Gonzalez, Pierre Carcabal, Marie Plazanet

摘要:

物理凝胶,即低分子量有机胶凝剂{ \textit甲基-4,6-O-亚苄基- $α$ -D-吡喃甘露糖苷($α$ -manno)}在水和甲苯中的动力学通过中子散射探测。使用高胶凝剂浓度,我们能够确定,从几个ps到1 ns的时间尺度上,由胶凝剂形成的刚性网络固定的溶剂分子的数量。我们发现每个凝胶因子只有很少的甲苯分子参与凝胶因子糖部分之间通过氢键形成的网络。然而,在水中,导致凝胶形成的相互作用较弱,涉及偶极、疏水或$π-π$相互作用,并且在胶凝剂和周围的水之间形成氢键。因此,每个胶凝因子约10至14个水分子通过网络的存在而被固定。这项研究表明,中子散射可以提供有价值的信息的行为,溶剂限制在分子凝胶。

英文摘要:

The dynamics of a physical gel, namely the Low Molecular Mass Organic Gelator {\textit Methyl-4,6-O-benzylidene-$α$ -D-mannopyranoside ($α$-manno)} in water and toluene are probed by neutron scattering. Using high gelator concentrations, we were able to determine, on a timescale from a few ps to 1 ns, the number of solvent molecules that are immobilised by the rigid network formed by the gelators. We found that only few toluene molecules per gelator participate to the network which is formed by hydrogen bonding between the gelators' sugar moieties. In water, however, the interactions leading to the gel formations are weaker, involving dipolar, hydrophobic or $π-π$ interactions and hydrogen bonds are formed between the gelators and the surrounding water. Therefore, around 10 to 14 water molecules per gelator are immobilised by the presence of the network. This study shows that neutron scattering can give valuable information about the behaviour of solvent confined in a molecular gel.

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