Xue Yi-Nan, Zeng Xiang-Bing, Wu Bo-Wen, Li Ya-Xin, Cseh Liliana, Yang Shu-Gui, Liu Jie, Gehring Gillian A, Liu Feng, Ungar Goran
Shaanxi International Research Center for Soft Matter, State Key Laboratory for Mechanical Behaviour of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.
School of Chemical, Materials and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK.
Angew Chem Int Ed Engl. 2025 Jul 7;64(28):e202505548. doi: 10.1002/anie.202505548. Epub 2025 May 15.
We investigate two unusual phenomena in self-assembly of anisotropic molecules from isotropic (Iso) melt: a heat-capacity (C) maximum and spontaneous formation of the recently discovered chiral liquid (Iso*). Based on experiments on new nonchiral monomers, dimers, and polymers, we construct a statistical theory that shows why many complex meso-structures form in two stages: continuous equilibrium growth of nano-clusters in melt through strong interactions, causing the C-maximum, followed by establishment of positional long-range order (LRO) through a weak first-order transition. We also show why many achiral compounds additionally form an intermediate chiral Iso* liquid through what we find is a second-order transition. We propose that the first process is equivalent to "supramolecular polymerization" in solutions, where the lack of intercluster interaction rules out LRO. Furthermore, we argue that separation into a broad and a sharp transition is universal in condensed matter where strong interactions by themselves cannot lead to LRO, either because the clusters are 1D or due to strong frustration. Clusters must first grow to critical size when, at T, the combined weak interactions reach ∼kT, prompting LRO formation. A situation similar to that in soft self-assembly is seen in spin ordering in magnetic crystals, but only near 0 K.
我们研究了各向异性分子从各向同性（Iso）熔体自组装过程中的两种异常现象：热容量（C）最大值以及最近发现的手性液体（Iso*）的自发形成。基于对新型非手性单体、二聚体和聚合物的实验，我们构建了一种统计理论，该理论揭示了为何许多复杂的介观结构分两个阶段形成：通过强相互作用在熔体中纳米团簇的连续平衡生长，导致出现C最大值，随后通过弱一级转变建立位置长程有序（LRO）。我们还揭示了为何许多非手性化合物会通过我们发现的二级转变额外形成一种中间手性Iso*液体。我们提出，第一个过程等同于溶液中的“超分子聚合”，其中团簇间缺乏相互作用排除了LRO。此外，我们认为，在凝聚态物质中，分离为一个宽泛的转变和一个尖锐的转变是普遍存在的，在这种情况下，强相互作用本身无法导致LRO，这要么是因为团簇是一维的，要么是由于强烈的挫折感。当在温度T时，组合的弱相互作用达到约kT，促使LRO形成时，团簇必须首先生长到临界尺寸。在磁性晶体的自旋有序中可以看到与软自组装中类似的情况，但仅在接近0 K时。
