Topic
Polyurea
About: Polyurea is a research topic. Over the lifetime, 3928 publications have been published within this topic receiving 40653 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: The rational design of hindered urea bonds are reported and the use of them to make polyureas and poly(urethane-ureas) capable of catalyst-free dynamic property change and autonomous repairing at low temperature is reported.
Abstract: Polymers bearing dynamic covalent bonds may exhibit dynamic properties, such as self-healing, shape memory and environmental adaptation. However, most dynamic covalent chemistries developed so far require either catalyst or change of environmental conditions to facilitate bond reversion and dynamic property change in bulk materials. Here we report the rational design of hindered urea bonds (urea with bulky substituent attached to its nitrogen) and the use of them to make polyureas and poly(urethane-urea)s capable of catalyst-free dynamic property change and autonomous repairing at low temperature. Given the simplicity of the hindered urea bond chemistry (reaction of a bulky amine with an isocyanate), incorporation of the catalyst-free dynamic covalent urea bonds to conventional polyurea or urea-containing polymers that typically have stable bulk properties may further broaden the scope of applications of these widely used materials.
676 citations
TL;DR: In this paper, the rate-dependent stress-strain behavior of one polyurea and three representative polyurethane materials is studied by dynamic mechanical analysis, quasi-static compression testing and split Hopkinson pressure bar (SHPB) testing.
371 citations
Patent•
24 May 1999
TL;DR: In this article, a medical device comprising an organic polymer substrate material having a coating thereon, the coating comprising an interpenetrating network of two different hydrogel polymers.
Abstract: A medical device comprising an organic polymer substrate material having a coating thereon, the coating comprising an interpenetrating network of two different hydrogel polymers, one of which is a polyurethane/polyurea hydrogel polymer, the polyurethane/polyurea hydrogel polymer being linked to the substrate material by covalent urea linkages.
356 citations
TL;DR: In this paper, Fourier transform infrared spectroscopy was used to characterize the distribution of hydrogen bonds in polyurethane and polyurea and their blends with poly(ethylene glycol) was examined.
Abstract: The effect of hydrogen bonding on the phase behavior of a chemically similar polyurethane and polyurea and their blends with poly(ethylene glycol) is examined. The polyurethane and polyurea were synthesized from the same diisocyanate, 1,5-diisocyanato-2-methylpentane, using an aromatic diol and aromatic diamine, respectively. Fourier transform infrared spectroscopy was used to characterize the distribution of hydrogen bonds in these polymers and their blends. The distribution of hydrogen bonds in the polyurethane homopolymer was found to be quite similar to that found in an amorphous polyurethane studied previously in this laboratory. However, upon annealing, some sort of ordered structure was detected spectroscopically. The polyurea formed an equivalent ordered structure much more readily at room temperature. Ordered hydrogen-bonded domains were also detected in the spectra of the blends, either after an extended time at room temperature or after annealing at an elevated temperature. The formation of ord...
337 citations
TL;DR: In this article, the uniaxial compression stress-strain behavior of polyurea and polyurethane over a wide range in strain rates, from 0.001−s−1 to 10,000 s−1, was reported.
328 citations