Biodegradable and reprocessable cellulose-based polyurethane films for bonding and heat dissipation in transparent electronic devices

It is challenging and attractive to prepare the bio-based polymers with comparable or even improved properties in terms of sustainability and economics. Here, the cellulose-based polyurethane films with ethyl cellulose as a soft segment to fully substitute polyether polyols were prepared in a facile and environmentally friendly preparation process. Moreover, the selected sample exhibited high transparency (transmittance of 84.4%), good shape memory behavior (shape fixation ratio of 95% and shape recovery ratio of 94.4%), tensile strength (9.2 MPa), good biodegradability (degradation half-life ( t 1/2 ) of 38 d) and excellent reprocessability (recycled 10 times). Especially, the cellulose-based polyurethane films performed the role of adhesive bonding with the different substrates. In addition, by adding Al 2 O 3 nanoparticles , the EC-PU composites not only exhibited high transparency and excellent adhesive strength but also improved thermal conductivity. At a low filler loading (2.5 wt%) of Al 2 O 3 nanoparticles (30 nm), the Al 2 O 3 -EC-PU4 film not only maintained higher transmittance of 73.6% but also had excellent lap-shear strength of 3.04 MPa. Moreover, both the thermal conductivity and thermal diffusivity of Al 2 O 3 -EC-PU4 film reached as high as 0.92 W/mK and 14.81 mm 2 /s, which are 146% and 1048% higher than the blank sample. Therefore, it has great potential in developing high performance bio-based plastics and transparent electronic fields.