I have a formulation project about synthesis of alcohol-ester soluble polyurethane resin. I know that esters such as ethylacetate (EA) are good solvent for polyurethane resin. But, Ethanol (EtOH) is not a solvent for PU resin. What helps PU resin to be soluble in EtOH-EA solution? Indeed, I am looking for a good starting point.
There are attraction between ET-OH and EA through H-bonding and EA make attraction with Urethane through dipole-dipole interaction (carbonyl group)let urethane to dissolved
I would suggest creating a triangular phase diagram between your polyurethane, EA and ET-OH. Remember, your polyurethane should be based on di-alcohol and di-isocyante to be soluble in any solvent (linear chain molecule).
basically, you prepare a solution of ET-OH and EA are various concentration ratio varying from 90:10 to 10:90 in beakers. now add know amount of polyurethane (preferably as less as possible ) and stir solutions overnight without heating. Observe in the morning for clear solutions. Discard cloudy ones. Once you have a ration of solvents now you can try increasing the polyurethane concentration. Good luck!
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