创新背景

聚合物在今天的社会生活生产中无处不在，但它们积累塑料废物、制造传统聚合物的不可持续性损害环境。聚合物通常是通过使用共价键将一串称为单体的构建块连接在一起制成，但这些强力键使报废塑料制品很难被解聚回收单体再利用。

创新过程

日本理化学研究所（RIKEN）的研究人员开发出一种环保的聚合物，可在无溶剂工艺中催化自身，这一发现或可推动使用可持续工艺制造的固有可回收聚合物材料发展。相比之下，超分子聚合物由通过氢键等相互作用保持在一起的单体阵列组成，氢键比共价键更弱，因此更可逆。

研究人员表示，用于制造超分子聚合物的溶剂限制了其应用和可持续性。在未来，无溶剂化学品制造可能是唯一获得批准的化学工艺，因为其他制造工艺中使用的大量溶剂对环境造成了严重破坏。

研究团队发现名为邻苯二甲腈的楔形分子在加热时会熔化形成多种薄的绿色结晶纤维，是呈棒状的超分子聚合物。当四个楔形块聚集在一起形成一个扁平的圆形圆盘时，聚合过程就此开始。然后，圆盘形组件（单体）可以作为接下来四个楔形前体分子结合的模板表面，为结构添加一层。重复该过程，用每一层新聚合物催化下一层的形成，直到形成长棒状结构。研究团队将他们的工艺命名为无溶剂自催化超分子聚合。

这些超分子聚合物的结晶纤维的机械性能类似于聚甲基丙烯酸烷基酯的机械性能，聚合物被用于有机玻璃等一系列应用。研究通过在特定时间点将替代前体分子添加到混合物中来创建其超分子聚合物的更复杂版本，从而形成“嵌段共聚物”，其沿每个棒的长度具有不同单体的条带。无溶剂自催化超分子聚合可用于从一系列起始材料制备超分子聚合物，可能适用于多环芳烃和环肽的合成。

创新关键点

通过使用无溶剂超分子聚合物合成生产结晶超分子纤维，开发环保绿色的方法使聚合物生产更具可持续性。

Green synthesis of supramolecular polymers using solvent-free process

Researchers at Japan's RIKEN Institute have developed an environmentally friendly polymer that catalyzes itself in a solvent-free process, a discovery that could boost the development of inherently recyclable polymer materials made using sustainable processes. In contrast, supramolecular polymers consist of arrays of monomers held together by interactions such as hydrogen bonds, which are weaker and therefore more reversible than covalent bonds.

The researchers say the solvents used to make the supramolecular polymer limit its application and sustainability. In the future, solvent-free chemical manufacturing may be the only approved chemical process, as the large number of solvents used in other manufacturing processes wreak havoc on the environment.

The team found that the wedge-shaped molecules, called phthalonitrile, are rod-like supramolecular polymers that melt when heated to form a variety of thin green crystalline fibers. The process begins when the four wedges come together to form a flat circular disk. The disc-shaped component (monomer) can then serve as a template surface for binding of the next four wedge-shaped precursor molecules, adding a layer to the structure. The process is repeated, with each new layer of polymer catalyzing the formation of the next until a long rod-like structure is formed. The research team named their process solvent-free autocatalytic supramolecular polymerization.

The mechanical properties of the crystalline fibers of these supramolecular polymers are similar to those of polyalkyl methacrylate, which are used in a range of applications such as plexiglas. Studies create more complex versions of their supramolecular polymers by adding alternative precursor molecules to the mixture at specific points in time, resulting in "block copolymers" with bands of different monomers along the length of each rod. Solvent-free autocatalytic supramolecular polymerization can be used to prepare supramolecular polymers from a range of starting materials and may be suitable for the synthesis of PAHs and cyclic peptides.