Fischer J, Lang M, Sommer J-U
Leibniz Institut für Polymerforschung Dresden, Hohe Straße 6, 01069 Dresden, Germany.
J Chem Phys. 2015 Dec 28;143(24):243114. doi: 10.1063/1.4933228.
Different methods for creating Olympic gels are analyzed using computer simulations. First ideal reference samples are obtained from freely interpenetrating semi-dilute solutions and melts of cyclic polymers. The distribution of pairwise concatenations per cyclic molecule is given by a Poisson-distribution and can be used to describe the elastic structure of the gels. Several batches of linear chains decorated with different selectively binding groups at their ends are mixed in the "DNA Origami" technique and network formation is realized. While the formation of cyclic molecules follows mean field predictions below overlap of the precursor molecules, an enhanced ring formation above overlap is found that is not explained by mean field arguments. The "progressive construction" method allows to create Olympic gels with a single reaction step from a concentrated mixture of large compressed rings with a low weight fraction of short chains that are below overlap concentration. This method, however, is limited by the difficulty to obtain a sufficiently high degree of polymerization of the large rings.
使用计算机模拟分析了制备奥运凝胶的不同方法。首先，从环状聚合物的自由互穿半稀溶液和熔体中获得理想的参考样品。每个环状分子的成对连接分布由泊松分布给出，可用于描述凝胶的弹性结构。在“DNA折纸”技术中，将几批在末端装饰有不同选择性结合基团的线性链混合，实现网络形成。虽然环状分子的形成在低于前体分子重叠时遵循平均场预测，但发现在高于重叠时环状形成增强，这无法用平均场理论解释。“渐进构建”方法允许从具有低于重叠浓度的短链低重量分数的大压缩环的浓缩混合物通过单个反应步骤制备奥运凝胶。然而，该方法受到难以获得足够高聚合度的大环的限制。
