Abstract
Currently, much attention is given to the functionality and recyclability of waterborne polyurethane (WPU). Herein, ε-caprolactone was used as a chain extender for grafting onto perylene bisimide (PBI) and 1,4-butanediol (BDO) via ring-opening reactions to obtain PBI-PCL and BDO- PCL. Then, two kinds of WPU, namely PBI-WPU (PWPU) and BDO-WPU (BWPU), were fabricated using PBI-PCL/polytetrahydrofuran ether glycol (PTMG) and BDO-PCL/PTMG, respectively, as mixed soft segments. The properties and appearance of PWPU and BWPU emulsions were analyzed in terms of particle size, zeta potential and TEM images, and the results showed that PWPU emulsions had uniform particle size distribution and decent storage stability. AFM and DMA results revealed that PWPU films possessed a more significant degree of microphase separation and a higher glass transition temperature (Tg) than BWPU films. The PWPU films displayed good shape-memory and mechanical properties, with tensile strength up to 58.25 MPa and elongation at break up to 1241.36%. TGA analysis indicated that PWPU films had better thermal stability than BWPU films. More importantly, the PWPU films could be dissolved in a mixed solvent of acetone/ethanol (v/v = 2:1) at room temperature. The dissolved PWPU could be dispersed in deionized water to prepare waterborne polyurethane again. After the recycling process was repeated three times, the recycled PWPU emulsion still exhibited good storage stability. The recycled PWPU films maintained their original thermal and mechanical properties. Comparing the properties of BWPU and PWPU showed that the soft segment structure had important influence on waterborne polyurethane performance. Therefore, PWPU may have great potential applications in making recycling and shape-memory coating or paint.
Highlights
Polyurethane can be classified into waterborne polyurethane (WPU) and solvent-based polyurethane (SPU), based on the dispersion media
The difference between WPU and SPU is that the production and use of WPU does not release a large amount of volatile organic compounds (VOC), which is an inevitable problem in the production and use of SPU [3,4]
The strong band at 1699 cm−1 and 1662 cm−1 belongs to the –C–N vibrations in perylene bisimide (PBI)-OH, and it is recognizable in PBI-PCL5000 and PWPU5000
Summary
Polyurethane can be classified into waterborne polyurethane (WPU) and solvent-based polyurethane (SPU), based on the dispersion media. Developing a WPU film which can be dissolved in low-boiling solvent, and the recycled solution can be dispersed by water again, is very useful for green recycling of waterborne polyurethane. Lu et al, reported that, compared to the samples without PBI, the PSMP (prepared by PCL as the soft segment and PBI as chain extender) with 5.5 wt.% PBI showed the highest tensile properties and good shape-memory properties [21]. These reported PBI-modified PUs are all solvent-based polyurethanes. The effect of PBI on WPU has not yet been reported
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
