A green method for producing crystalline supramolecular fibers assures to make polymer production more sustainable.
A polymer that catalyzes its own formation in an eco-friendly solvent-free procedure has been established by an all-RIKEN team of chemists. The discovery might lead to the development of naturally recyclable polymer products that are made using a sustainable procedure.
Polymers are common today, however they are harmful to the environment through the accumulation of plastic waste and the unsustainable nature of traditional polymer manufacture. Polymers are generally made by linking together strings of building blocks, understood as monomers, using covalent bonds. But these strong bonds make it hard to take used, end-of-life plastic items and de-polymerize them to recuperate the monomers for reuse.
Figure 1: Wedge-shaped precursor particles (top left) come together to develop a rod-shaped supramolecular polymer composed of their reductively cyclotetramerized disk-shaped monomers, with each brand-new layer of the growing polymer templating the development of the next (1 and 2 reveal the preorganization of wedge-shaped precursor phthalonitrile particles, and 3 shows reductive cyclotrimerization to provide a disk-shaped phthalocyanine monomer). Credit: © 2022 RIKEN Center for Emergent Matter Science
Supramolecular polymers, on the other hand, consist of arrays of monomers held together by interactions such as hydrogen bonds, which are weaker, and hence more reversible, than covalent bonds.
Nevertheless, the solvents utilized for making supramolecular polymers limit their application and sustainability. “Within 20 years, solvent-free chemical production might be the only accepted chemical procedures, since the large volumes of solvent utilized in other manufacturing processes are too harmful to the environment,” says Takuzo Aida from the RIKEN Center for Emergent Matter Science (CEMS).
Aidas group has been investigating wedge-shaped molecules called phthalonitriles. Now, he and 9 CEMS coworkers have discovered that these substances melt when warmed and after that form several thin green crystalline fibers, which are rod-shaped supramolecular polymers.
The polymerization procedure is started when 4 of the wedge-shaped pieces come together to form a flat, circular disk. The disk-shaped assembly– the monomer– can then act as a design template surface area for the next four wedge-shaped precursor molecules to integrate, including a layer to the structure. This process is duplicated, with each new layer of the polymer catalyzing the formation of the next, till long rod-like structures type (Figure 1). The group named their procedure solvent-free autocatalytic supramolecular polymerization.
” The mechanical properties of the crystalline fibers of these supramolecular polymers are comparable to those of poly( alkyl methacrylates),” Aida states. These traditional polymers are utilized for a variety of applications, including plexiglass.
The team might produce more complicated variations of their supramolecular polymers by including alternate precursor molecules into the mix at certain time points, thus forming block copolymers with bands of different monomers along the length of each rod.
Solvent-free autocatalytic supramolecular polymerization might be used to make supramolecular polymers from a variety of starting products. “It might apply to the synthesis of polycyclic cyclic peptides and fragrant hydrocarbons,” Aida says.
Recommendation: “Solvent-free autocatalytic supramolecular polymerization” by Zhen Chen, Yukinaga Suzuki, Ayumi Imayoshi, Xiaofan Ji, Kotagiri Venkata Rao, Yuki Omata, Daigo Miyajima, Emiko Sato, Atsuko Nihonyanagi and Takuzo Aida, 14 October 2021, Nature Materials.DOI: 10.1038/ s41563-021-01122-z.
Polymers are common today, but they are detrimental to the environment through the build-up of plastic waste and the unsustainable nature of traditional polymer manufacture. Polymers are usually made by connecting together strings of structure blocks, understood as monomers, utilizing covalent bonds. This process is repeated, with each new layer of the polymer catalyzing the formation of the next, until long rod-like structures kind (Figure 1). The team named their process solvent-free autocatalytic supramolecular polymerization.