Updated September 18, 2025:
In this stage of the project, we continued our evaluation of NIPU (Non-Isocyanate Polyurethane) coatings by moving beyond the earlier phase, where we had already assessed their thermal stability, resistance to water, and hardness, and we aimed to understand how these coatings behave under fire exposure, how robust and interconnected their internal structure is, how resistant they are to corrosive environments, and whether they can stop common stains like ink from sticking to surfaces, which means that our progress report now provides a full picture of how far we have come in testing these novel materials; starting with fire testing, we compared plain uncoated wood to wood coated with three different NIPU formulations known as CSBO_CYS, CSBO_DETA, and CSBO_TETA, and what we discovered was that uncoated wood ignited almost instantly at around three seconds and burned for about a minute and a half with about seven percent of its mass lost, while the coated samples delayed ignition to between four and five seconds, burned for much shorter times, and showed greatly reduced weight loss, with CSBO_DETA in particular standing out by catching fire only after about five seconds, burning for just thirty-eight seconds, and losing only about one and a half percent of its mass, while the other two coatings also offered good protection but with slightly higher burning times and weight loss, so the progress here clearly demonstrates that the NIPU coatings provide an effective barrier to flames; moving next to the gel content tests, which measure how “cross-linked” or interconnected the internal network of the coating is, we immersed the materials in both water and toluene for twenty-four hours and then checked how much of the structure remained intact, and we found that all three coatings maintained more than ninety-five percent of their original structure, meaning they are very strongly cross-linked and do not break down easily, though in water their performance dipped slightly due to the hydrophilic or water-loving parts of their chemistry, but overall the result shows strong durability, which is key progress because cross-linking is directly tied to how tough and long-lasting a material will be; in terms of chemical resistance, our progress involved applying these coatings to stainless steel coupons and exposing them to saltwater, a strong acid (sulfuric acid), and a strong base (sodium hydroxide), and when checked after one hour, all coated surfaces held up against saltwater and base while uncoated surfaces stained in acid, but after twenty-four hours, both coated and uncoated surfaces showed corrosion in acid, saltwater remained harmless, and in base the uncoated steel stained while CSBO_CYS and CSBO_TETA stayed intact and CSBO_DETA began corroding, which means that the coatings generally resist salt and base environments but acids remain too aggressive, an important progress checkpoint that highlights both strengths and limits; finally, our ink repellence testing showed that while uncoated wood absorbed oil-based marker ink permanently, all coated surfaces allowed the ink to be wiped away completely with a tissue, leaving no trace, which is notable progress since it demonstrates an unexpected benefit of cleanliness and easy maintenance; taken together, the progress we report is that NIPU coatings have advanced from being only theoretically promising to being practically tested across multiple conditions, and the accumulated evidence shows that they significantly improve fire resistance, structural integrity, resistance to salt and alkaline chemicals, and prevent ink staining, though acid resistance still remains an area for improvement, and as part of ongoing progress, we are now exploring variations in the formulation, particularly by adjusting the amount of diamine cross-linker used, which may further improve fire protection and other performance aspects, and thus the progress so far strongly supports the potential of NIPU coatings for real-world applications in industries such as construction, furniture, and protective finishes, where surfaces need to resist fire, chemicals, and stains while remaining strong and durable over time.
View uploaded report 
The final results of this project clearly show that NIPU (Non-Isocyanate Polyurethane) coatings deliver multiple layers of protection to wood and metal surfaces and can be considered highly effective in several key areas, because when we analyze all the experiments as a whole, the coatings consistently perform better than uncoated surfaces, and in some cases, dramatically so; the flammability tests provide some of the most striking results, since uncoated wood ignites almost immediately within about three seconds, burns for a prolonged ninety seconds, and loses around seven percent of its material, while wood protected with the three NIPU coatings consistently resists ignition longer, burns for much shorter periods, and suffers far less weight loss, with the CSBO_DETA variant delivering the best result by delaying ignition to five seconds, burning for only thirty-eight seconds, and losing just one and a half percent of its weight, while CSBO_TETA and CSBO_CYS also cut burning times down to forty and fifty-four seconds respectively with proportionally lower mass loss, which means that in terms of fire safety, the final result is unambiguous: these coatings make wood safer and more resistant to fire damage; looking at gel content as a measure of cross-linking and structural robustness, all three coatings maintained more than ninety-five percent of their integrity after being soaked in both water and toluene, which demonstrates a very high level of internal stability, and although they performed slightly less well in water due to hydrophilic components in their chemistry, the overall takeaway is that the final results confirm these coatings are strongly bonded materials that will not easily fall apart or dissolve, making them reliable for long-term use; when we assess chemical resistance, the final results show a nuanced picture, since in saltwater all coatings completely protected the underlying steel even after twenty-four hours, and in sodium hydroxide, CSBO_CYS and CSBO_TETA remained intact while CSBO_DETA began to show signs of corrosion, and in sulfuric acid, both coated and uncoated surfaces corroded over time, which proves that while the coatings are effective against salt and alkaline environments, acids are still too strong for them, so the final outcome is positive but with a known limitation; the ink repellence testing provides another clear and practical result, as uncoated wood absorbed ink permanently while all coated wood allowed marker lines to be wiped away cleanly with a tissue, leaving no stains, showing that the coatings can keep surfaces clean and easy to maintain, which is a valuable property for everyday use; therefore, the final consolidated results across all tests demonstrate that NIPU coatings make wood significantly more fire-resistant, give the material a highly stable and cross-linked structure, provide excellent resistance to salt and alkaline chemical damage, and add a layer of protection against ink stains, though they cannot fully resist strong acids, and together these results point to the conclusion that NIPU coatings are practical, multifunctional materials with applications in construction, furniture, and protective coatings, where they can improve safety, durability, and cleanliness, and importantly, the project’s final results also suggest clear pathways for further improvement by adjusting the formulation—particularly the amount of diamine cross-linker used—which may boost flame resistance and chemical durability even more, so overall the final results are both encouraging and conclusive, showing that NIPU coatings are not just a laboratory success but a material with real-world potential ready for the next steps of industrial application and refinement.