Free-standing 2D polymer materials with graphene-like crystalline layers hold great promise for many state-of-art applications. However, their fabrication remains challenging. A ferrocene tethered cyclopolymer (pFcMMA) is synthesized via the free radical polymerization of a divinyl monomer in this work. PFcMMA has a high degree of cyclization, but is not a stereo-regular structure like most vinyl polymers synthesized in free radical polymerization. PFcMMA can crystallize on the surface to form 2D crystals, which is evidenced by the birefringence phenomena, DSC and XRD analysis, and microscopic observation. Powder XRD of crystalline pFcMMA shows sharp interlayer diffraction, indicative of a highly crystalline phase. The crystallization process is supposed to follow the nonclassic crystallization pathway, i.e. the orientation of cyclopolymer main chains followed by the conformation transition of the side groups to form 2D crystalline layers. Variable temperature XRD combined with DSC analysis and polarizing optical microscopic observation demonstrate that the 2D crystalline phase begins to transition to a 3D crystalline phase at about 45 °C, the latter has a melting point at about 60 °C. The solid-solid crystalline transition is reversible and without intermediate melting, and the 2D crystalline phase is more stable at room temperature than the 3D phase. It is rationalized that nucleation from solutions is predominantly an entropy-driven process, while interactions between side groups and those between far separated main chains also benefit the formation of 2D crystalline phase. The commonalities of the crystallization processes of cyclopolymers are discussed.

具有类石墨烯结晶层的独立式二维聚合物材料在许多最先进的应用中具有很大的前景。然而，它们的制造仍然具有挑战性。在这项工作中，通过二乙烯基单体的自由基聚合合成了二茂铁系链环聚合物 (pFcMMA)。PFcMMA 具有高度环化，但不像大多数在自由基聚合中合成的乙烯基聚合物那样具有立体规整结构。PFcMMA 可以在表面结晶形成二维晶体，​​双折射现象、DSC 和 XRD 分析以及显微镜观察都证明了这一点。结晶 pFcMMA 的粉末 XRD 显示出尖锐的层间衍射，表明存在高度结晶相。结晶过程应该遵循非经典结晶途径，即 环聚合物主链的取向，然后是侧基的构象转变，形成二维结晶层。变温 XRD 结合 DSC 分析和偏光光学显微镜观察表明，2D 晶相在约 45°C 时开始转变为 3D 晶相，后者的熔点约为 60°C。固-固结晶转变是可逆的并且没有中间熔化，并且2D结晶相在室温下比3D相更稳定。合理的是，溶液的成核主要是熵驱动的过程，而侧基之间的相互作用以及远距离主链之间的相互作用也有利于二维晶相的形成。