Self-Cross-Linkable Anionic Waterborne Polyurethane-Silanol Dispersions from Cottonseed-Oil-Based Phosphorylated Polyol as Ionic Soft Segment

Phosphorylated polyols (phospols) derived from cotton-seed oil (CSO) were employed to synthesize novel, DMPA- (dimethylol propanoic acid-) free, catalyst-free, waterborne polyurethane dispersions (PUDs). Three different phospols bearing both hydroxyl and ionizable phosphoryl groups were synthesized through the ring-opening hydrolysis of epoxidized cottonseed oil (ECSO) in the presence of ortho-phosphoric acid. The phospols were characterized by H-1 NMR spectroscopy, FTIR spectroscopy, and gel permeation chromatography. Three phospols (phospol-P5,-P10, and-P15) having hydroxyl numbers of 130, 160, and 180 mg of KOH/g, respectively, were used as internal emulsifiers in waterborne PUDs with isophorone diisocyanate and 3-aminopropyltriethoxysilane (APTES). All three PU dispersions showed excellent storage stabilities (>6 months), and the average particle sizes of the PUDs ranged from 30 to 68 nm. The cured films were characterized by FTIR (ATR) and solid-state Si-29 NMR analyses. The hydrophobicities of the films were measured by the contact angle technique, and their anticorrosive properties were studied by the polarization technique. The films of the phospol-P5-based dispersion exhibited the highest tensile strength, thermal stability, T-g value, and contact angle and the best anticorrosive properties. All of the experimental results revealed that both the hydroxyl contents of the phospols and the extents of siloxane cross-linking played important roles in determining the thermomechanical properties, hydrophobicities, and anticorrosive properties of the corresponding PUD films.