Triblock copolymers containing hydrophilic PEO blocks as effective polyols for organic solvent-free waterborne poly(urethane-urea)s

摘要

The structure, morphology and final properties of synthesized waterborne poly(urethane-urea)s (WPUU) based on triblock copolymers containing hydrophilic poly(ethylene oxide) PEO block as polyol has been studied. Different molecular weight poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO) and poly(propylene oxide-b-ethylene oxide-b-propylene oxide) (PPO-b-PEO-b-PPO) triblock copolymers were used as polyols acting as soft segment. A Volatile Organic Compounds (VOCs) free synthesis procedure was followed to synthesize WPUU dispersions. Particle size, solid content and viscosity of the WPUU dispersions were measured. Atomic force microscopy was used to study the morphology, whereas size exclusion chromatography helped determining molecular weight of the WPUU films, prepared by solvent casting. Chemical structure was determined by FTIR and H-1 NMR. Moreover, transmittance and thermal and mechanical properties of the WPUU films were also investigated. The use of PEO-b-PPO-b-PEO triblock copolymer led to dispersions with higher molecular weights and viscosities. WPUU films based on this triblock copolymer showed better mechanical properties, nevertheless they exhibited a lower transparency. All triblock copolymer based WPUU films led to nanostructured materials, which can act as template for dispersion of different kind of fillers extending possible application of waterborne polyurethanes. This work spotlights the possibility to synthesize waterborne poly (urethane-urea) dispersions with tailored properties using triblock copolymers as polyols.