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M. J. Taublaender, M. M. Unterlass:
"Towards Materials Applications of Polyimides Generated by Hydrothermal Polymerization";
Poster: Bordeaux Polymer Conference, Bordeaux; 2018-05-28 - 2018-05-31.

Fully aromatic polyimides (PIs) belong to the class of high-performance polymers and exhibit outstanding mechanical stability as well as high thermal and chemical resistance. Therefore, applications of PIs range from the use in bearings, to printed circuit boards to satellites.

We have recently reported a novel synthetic approach towards PIs: Hydrothermal polymerization (HTP).[1][2] This geomimetic technique is inspired by natural mineral formation in hydrothermal veins and generates PIs directly from the monomers in solely hot H₂O. Due to the absence of toxic and harmful catalysts and solvents (conventional PI syntheses employ isoquinoline and DMF or NMP), HTP is an environmentally friendly polymerization technique. In a typical HTP experiment (Fig. 1A) the comonomers are simply dispersed in H₂O and the mixture is heated to elevated temperatures (> 180˚C) in a closed vessel aka autoclave. HTP generates PIs of full crystallinity and unique morphologies (Fig. 1B) that can moreover be intentionally altered by the application of additives (Fig. 1C).[4] The feature of full crystallinity is extremely promising: It enhances chemical and thermal stability in these polymers. Hence, the properties that are most important to PIs´
applications benefit from their preparation via HTP.

Hydrothermally obtained PI microparticles could be used as particulate additives, in e.g. composites or paints and varnishes. In order to bring PI particles from HTP closer to real applications it is mandatory to tune their dimensions, morphology and functionality. With this contribution, we present our recent studies on decreasing the size of hydrothermally generated PI particles, altering their morphology, and functionalizing their surfaces.

[1] B. Baumgartner, M. J. Bojdys, M. M. Unterlass, Polym. Chem. 2014, 5, 3771.
[2] Baumgartner, M. J. Bojdys, P. Skrinjar, M. M. Unterlass, Macromol. Chem. Phys. 2016, 217, 485.
[3] M. M. Unterlass, Biomimetics 2017, 2(2), 8.
[4] M. J. Taublaender, M. Reiter, M. M. Unterlass, Macromol. Chem. Phys. 2017, doi:
10.1002/macp.201700397.