Anionic waterborne polyurethane-imide dispersions from cottonseed oil based ionic polyol

In the present work a series of novel, DMPA (dimethylol propionic acid) free, catalyst free, anionic waterborne polyurethane-imide (PUID) dispersions have been successfully synthesized by using maleated cottonseed oil polyol (MAHCSO) as an ionic soft segment, tolylene diisocyanate and dianhydrides as chain extenders. Three different aromatic dianhydrides have been employed as chain extenders to introduce the imide groups in polyurethane hard segment and their effect on thermo-mechanical properties and phase compatibility between hard and soft segments have been investigated. The films cast from the dispersions were characterized by FT-IR (ATR), TGA, DMTA, tensile strength and contact angle measurements. It was found that the tensile properties, thermal stability, water contact angle, and Tg values of PUIDs were remarkably high compared to conventional PUDs. Presence of ionic soft segment in the segmented PU chain led to enhanced phase compatibility between the hard and soft segments. The complete substitution of DMPA which generally serves as an internal emulsifier in waterborne polyurethane dispersions was achieved by using a vegetable oil-based ionic soft segment.