Polyurethane is extremely elastic, wear-resistant and durable, and is used, for example, in cushions, fibers, thermal insulation materials, dyes, adhesives and car parts. Polyurethane is an industrially important polymer material, with an estimated worldwide market value of 75 billion dollars.
Most polyurethane today is synthesized by reacting diisocyanate with diol. However, isocyanate compounds are highly toxic, and the tightening of regulations on diisocyanate use has been increasing recently, especially in the EU, for health and environmental reasons. In recent years, active research continues in the synthesis of polyurethane without the use of isocyanate compounds with the aim of implementing a sustainable society.
However, most of the current methods are impractical due to various problems associated with them: They have low functionality as well as high environmental costs, and the quality of the obtained polyurethane is low and also expensive.
Against this backdrop, Kobe University Associate Professor Tsuda and AGC, combined their efforts to jointly develop a novel polyurethane synthesis method. The university-industry cooperation between the research group of Associate Professor Tsuda, pioneers of the Photo-on-demand organic synthesis method and AGC, a manufacturer of fluorinated compounds and polyurethane raw materials, created a new academic field and industrial activity based on the development of new polyurethane synthesis methods and functional materials.
The content of the research
Various fluorinated biscarbonates (BFBC) are synthesized through a condensation reaction of fluorinated carbonates, synthesized by the photo-on-demand synthesis method from fluorinated alcohol and chloroform, with diols. The BFBC generated can be purified simply by drying the obtained sample solution under reduced pressure, which enables the quantitative derivation of the target substance through a simple operation.
The synthesis of a non-isocyanate polyurethane (NIPU) with an average molecular weight of more than 10,000 was obtained by polycondensation of the obtained BFBC with diamine. NIPU synthesized without solvent showed little discoloration above 120°C, and that discoloration did not appear until 100°C. On the other hand, if a solvent is used, it can be polymerized at a low temperature, and a high molecular weight colorless NIPU can be obtained in high yield.
They produce a highly elastic colorless and transparent polyurethane through a suitable combination of BFBC and diamines in the hard and soft parts. They also succeeded in synthesizing a novel fluorinated polyurethane which is a colorless transparent oil.
The variety and types of polyurethane synthesized, which range from general purpose to specific applications, have the following benefits compared to previously reported NIPU synthesis methods:
- Any NIPU can be synthesized using commercial diols or diamines used in the industrial production of polyurethane by the isocyanate method, or which were originally used in the synthesis of NIPU.
- This is a synthesis method that does not use organic bases, metallic catalysts or solvents in the synthesis, to obtain a high quality NIPU without its content.
- The average molecular weight and terminal functional groups can be controlled by the admixture ratio of BFBC and the diamines. A NIPU prepared by this method with a molecular weight in the order of 10,000 can be used as a prepolymer to synthesize larger polymers or networked polymers.
- Reagents, solvents and eliminated fluoroalkyl alcohols can be recovered, and reused in the synthesis of this NIPU.
Visions of the future
The conventional polyurethane synthesis method using isocyanate has advantages from a cost perspective. However, the novel and useful non-isocyanate polyurethane (NIPU) synthesis method using this newly developed fluorinated carbonates and fluorinated biscarbonates can replace some conventional methods with the view of implementing a sustainable society, in addition to enabling the creation of functional polyurethanes that conventional methods cannot be synthesized.
Research is currently ongoing, from an academic and industrial perspective, with the aim of bringing this process to the market.
The study was published in the journal Bulletin of the Chemical Society of Japan.
Sasuga Hosokawa et al, Non-Isocyanate Polyurethane Synthesis by Polycondensation of Alkylene and Arylene Bis(fluoroalkyl) Bis(carbonate)s with Diamines, Bulletin of the Chemical Society of Japan (2023). DOI: 10.1246/bcsj.20230066
Provided by Kobe University
Citation: New method for polyurethane synthesis using fluorine compound developed (2023, July 21) retrieved 21 July 2023 from https://phys.org/news/2023-07-method-polyurethane-synthesis-fluorine-compound.html
This document is subject to copyright. Except for any fair dealing for the purpose of private study or research, no part may be reproduced without written permission. Content is provided for informational purposes only.