Abdelkader BOUAZIZ

The ratio of PEG to TDI is 1:2. Of course, I used different proportions, but after 2 to 3 minutes, the reaction mixture becomes hard and solid

Dear Mahvash Yarahmadi, I think you should work in solution, i.e., use a solvent. Please have a look at the following documents. My Regards

https://doi.org/10.1080/10426914.2010.530330

Thank you very much for your guidance, I am looking for making EBECRYL 230, this synthesis is two steps. In the first step, I need to synthesize the liquid precursor from TDI and PEG, and in the second step, by adding ethyl methacrylate to the first precursor, the synthesis of EBECRYL can be achieved. The syntheses should be carried out under the neat conditions, but unfortunately, when I mix the precursors in any ratio, urethane is very solid and rigid to form. EBECRYL 230 is liquid and colorless.

Dear Mahvash Yarahmad

1. The EBECRYL 230 is an aliphatic urethane diacrylate so it should be used aliphatic diisocyanate which gives a soft product at the end while you use TDI its aromatic and give a hard product

2. Scientifically the ratio should be PEG 200 & TDI in a ratio of 2 to 1 to give OH functional group at the both end of the compound which can react with methacrylate in the second stepto give your product.

My Regards

I used different ratios. Because the normal ratio of 1:2 didn't work

You have to use molar ratios PEG:Diisocyanate 2:1 instead of PEG:Diisocyanate 1:2

Usin a ratio PEG:Diisocyanate 1:2 you will have an excess od isocyanate groups. If you have moisture, these Isocyanates react with water releasing CO2 and leaving an amine group that reacts further with other isocyanate group increasing the molecular weight and giving you the.