Biocompatible elastomer of waterborne polyurethane based on castor oil and polyethylene glycol with cellulose nanocrystals

Abstract

► In our study, biocompatible waterborne polyurethane was synthesized. ► Eucalyptus globulus cellulose nanocrystals were introduced as reinforcing filler. ► The aspect ratio of E. globulus cellulose nanocrystals was 23.87. ► Elongation at break of the nanocomposite films showed no significant reduction. ► Thermal stability of the hard-segment of the waterborne polyurethane was enhanced. Biocompatible waterborne polyurethane (WPU) based on castor oil (CO)/polyethylene glycol (PEG) filled with low level loadings of Eucalyptus globulus cellulose nanocrystals (ECNs) was prepared. The ECNs obtained by sulfuric hydrolysis, consisted of ‘rod-like’ crystals with an average length and diameter of 518.0 ± 183.4 nm and 21.7 ± 13.0 nm, respectively. The nanocomposites with low level loadings of ECNs showed significant enhancement in tensile strength and Young's modulus from 5.43 to 12.22 MPa and from 1.16 to 4.83 MPa, respectively. SEM results showed well dispersion of ECNs in the WPU matrix. Furthermore, it was verified that the nanosized ECNs favored the hard-segments (HSs)/soft-segments (SSs) microphase separation of the WPU, causing shifts of the SS glass transition temperature ( T g,s ) and the HS melting temperature ( T m,h ) toward higher temperatures.