Polyurea Networks from Moisture-Cure, Reaction-Setting, Aliphatic Polyisocyanates with Tunable Mechanical and Thermal Properties

Author(s)
Antoni Sánchez-Ferrer, Viktor Soprunyuk, Max Engelhardt, Ralf Stehle, H. Albert Gilg, Wilfried Schranz, Klaus Richter
Abstract

A series of one-component aliphatic polyisocyanates has been synthesized and analyzed before and after the moisture-curing process. The resulting reactive polymers are monodisperse tetrafunctionalized reactive molecules that become aliphatic polyurea networks with enhanced tunability of mechanical, chemical, and thermal properties compared to polyurethane and polyamide counterparts. This tunability responds to the insertion of a soft polypropylene oxide polymer segment between two triisocyanate molecules, as demonstrated by two-dimensional diffusion ordered spectroscopy (2D DOSY) 1H NMR experiments and confirmed by Fourier transform infrared (FT-IR) spectroscopy. After curing, the polyurea networks show two glass transition temperatures: a characteristic of microphase-segregated block copolymers and a transient network due to the presence of the hydrogen bonds between the urea motives, as concluded from the evaluation of dynamic mechanical analysis (DMA), wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC) experiments. Therefore, controlling the volume fraction, i.e., the degree of polymerization of the polypropylene oxide soft domains, the cured materials exhibit viscoplastic or viscoelastic properties, making these polyurea networks very attractive as adhesives or sealants.

Organisation(s)
Physics of Functional Materials
External organisation(s)
Technische Universität München
Journal
ACS Applied Polymer Materials
Volume
3
Pages
4070–4078
No. of pages
9
ISSN
2637-6105
DOI
https://doi.org/10.1021/acsapm.1c00578
Publication date
07-2021
Peer reviewed
Yes
Austrian Fields of Science 2012
103018 Materials physics, 103023 Polymer physics
Keywords
ASJC Scopus subject areas
Polymers and Plastics, Process Chemistry and Technology, Organic Chemistry
Portal url
https://ucris.univie.ac.at/portal/en/publications/polyurea-networks-from-moisturecure-reactionsetting-aliphatic-polyisocyanates-with-tunable-mechanical-and-thermal-properties(c9bbf1a5-450a-4a9d-ab30-bce2a81423d9).html