Lal J, Hakem I F
Argonne National Laboratory, IPNS, Argonne, IL 60439, USA.
Eur Phys J E Soft Matter. 2004 Oct;15(2):217-23. doi: 10.1140/epje/i2004-10050-0.
The model system of poly(ethylene-oxide) or PEO, where the changing hydrogen-bond connectivity of the water has large effect on the conformation of the polymer chain, in mixtures of water and acetonitrile, is experimentally studied. The results show the existence of a threshold water content in the system at which the 3d connectivity of the water network begins. Unusual expansion of the polymer chain, an effect larger than that observed in either of the pure solvents, is seen. Upon addition of small amounts of a monovalent salt, binding of ion to polymer takes place in pure acetonitrile solutions. Salt ions begin to co-ordinate with water molecules at the same solvent ratio as the threshold for water network formation. Ions now no longer complex to PEO; instead, hydrogen bonding of water to the polymer strongly dictates conformation in this regime.
对聚环氧乙烷（PEO）的模型体系进行了实验研究，该体系中，在水与乙腈的混合物中，水的氢键连接性变化对聚合物链的构象有很大影响。结果表明，体系中存在一个阈值含水量，此时水网络的三维连接开始形成。观察到聚合物链出现异常膨胀，这种效应比在任何一种纯溶剂中观察到的都要大。在纯乙腈溶液中加入少量单价盐后，离子与聚合物发生结合。在与水网络形成阈值相同的溶剂比例下，盐离子开始与水分子配位。此时离子不再与PEO络合；相反，在这种情况下，水与聚合物的氢键对构象起强烈的主导作用。
