Polyimide Particle-Reinforced High-Performance Composites

Plastics, so-called polymers, are omnipresent in daily life: Our shelves at home, the toys and CDs they are filled with, the floor they stand on and the paint that makes them shine, everything is made out of polymers. Maybe less prominent than these commodity polymers, but by no means less important, are so-called high performance polymers (HPPs). HPPs are organic polymers with outstanding properties, such as high thermal stability and exceptional mechanical performance at very low weight. Initially designed for high-end applications in space ships, power plants or microelectronics, HPPs are steadily progressing into our daily lives, where they replace for example various forms of metals. Unfortunately, these outstanding features come at a high cost: The production of HPPs requires high energies and involves a variety of highly toxic solvents that are difficult to recycle. We have recently developed a benign alternative synthesis towards one type of HPPs, polyimides: hydrothermal polymerization (HTP). The process is inspired by a geological mineral formation process, so-called hydrothermal crystallization. Much as in the geological analogue, high crystallinities, i.e. superior order, can be produced by HTP. Most fascinatingly, this high crystallinity enhances the stability of these materials even further, making the resulting polyimides even better performing HPPs. With the project Polyimide Particle-Reinforced High-Performance Composites we intend to add a relatively small amount of outstandingly crystalline polyimide particles prepared by HTP to other polymers for generating composite materials of superior thermal, mechanical and chemical stability. The polymers that will be reinforced with crystalline polyimide particles have been selected based on their interest in applications were weight and stability matter, e.g. in aviation or electronics technologies.

In the project "Polyimide Particle-Reinforced High-Performance Composites", completely new types of composite materials were generated, i. e. materials that consist of two interconnected compounds. In order to produce high-performance composites with exceptional thermal, mechanical and chemical resistance, two materials components were combined that are already used in high-tech sectors such as aviation and microelectronics. Established plastics such as polyimide and epoxy systems were used. These were reinforced with recently developed highly crystalline polyimide particles, which were produced using the environmentally friendly process hydrothermal polymerisation (HTP). HTP is a geomimetic method and as such is based on geological mechanisms of formation of highly crystalline minerals. HTP allows for generating high-performance plastics such as polyimides in solely hot water at elevated pressures. The method is therefore much more environmentally friendly than common processes for the production of high-performance polymers, which are very energy-intensive and require the use of toxic chemicals. Like its geological counterpart, HTP also supplies highly ordered polyimides. This high order is extremely relevant: the crystallinity achieved promotes the stability of the polyimide plastics, which leads to even more efficient materials. By introducing hydrothermally produced, highly crystalline polyimide particles, composite materials with increased thermal, mechanical and chemical resistance could be produced. Since both the matrix materials and the fillers belong to the class of organic polymers from a chemical point of view, the composites produced are providing low weight. This is particularly relevant for potential applications in aerospace, electronics and the automotive sector, since in these areas a combination of extreme resilience and low weight is of the utmost importance