Innovative Thermoplastic Polymers Enhance Recycling Capabilities

The realm of 3D printing faces challenges due to the limited availability of high-performance and recyclable polymers. A newly developed class of polymers promises to address these issues effectively.

3D printing technology has expanded the horizon for material design and the production of plastic components. In the process known as Fused Filament Fabrication (FFF), a heated nozzle extrudes thermoplastic material, melting it and layering it to create the desired three-dimensional object. However, a significant hurdle remains: the scarcity of suitable recyclables.

Chemically recyclable polymers that can be broken down into their monomer building blocks for re-polymerization could significantly mitigate environmental concerns associated with plastic waste and reduce the reliance on fossil resources. A research team has recently unveiled a novel polymer class known as polythioenones in the journal Angewandte Chemie. These polymers can be both mechanically and chemically recycled, making them ideal for 3D printing applications while surpassing traditional polyolefins in mechanical performance. The breakthrough lies in a unique cyclic building block.

The synthesis of these innovative thermoplastic polymers with enhanced recyclability is heavily reliant on the design of appropriate monomers. Monomers are reactive small molecules that serve as the fundamental building blocks for polymers, typically comprising a few atoms with functional groups that enable chemical bonding. A team led by researchers at Georgia Institute of Technology has developed a new family of monomers and their resultant polymers, termed cyclic thioenones (CTE).

The rings of these monomers consist of seven carbon atoms and one sulfur atom, featuring a C=C double bond and a carbonyl group (C=O). They can be easily modified with different side groups. Through a process called ring-opening, these monomers polymerize by adding themselves to a growing polymer chain via a reversible Thia-Michael addition reaction. The research team also synthesized a derivative known as PCTE-Ph, which incorporates an aromatic six-membered ring (phenyl ring) as a side group.

According to reports from the Wissenschaft service, PCTE-Ph appears particularly promising. It is a thermally stable thermoplastic with excellent mechanical properties, capable of being processed with fillers and dyes using standard techniques and commercially available 3D printers. Components produced from this new material can be mechanically recycled by simply re-melting and reprocessing the material, retaining desirable properties such as tensile strength and thermal stability. Alternatively, a catalytic process can decompose the material back into its original monomers with a yield of 90%, allowing for further rounds of polymerization. Detailed insights into the process can be found in the original research article published in Angewandte Chemie.