Preparation of cellulose nanowhiskers‐reinforced polyurethane: Photoresponsive plastic with ultraviolet protection and superhydrophobic properties

Abstract

Transparent, photoluminescent, mechanically reliable, ultraviolet protective and superhydrophobic thermoplastic polyurethane (TPU) plastic was developed. A simple strategy to prepare transparent plastic that glows in the dark is to use alkaline earth strontium aluminate (AESA) nanoparticles trapped in thermoplastic polyurethane (TPUR). In order to improve both hardness and transparency of the plastic composite, cellulose nanowhiskers were used as a crosslinker and drier. The colorless plastic substrates exhibited a color shift to greenish when exposed to ultraviolet source. Transmission electron microscope (TEM) was employed to examine the morphology of AESA nanoparticles (8–15 nm in diameter) and cellulose nanowhiskers (3–7 nm in width and 645–665 nm in length). Morphological studies and hardness parameters were used to assess the TPUR samples. Excitation and emission spectral analyses were also employed to study the photoluminescence characteristics. The colorless plastic substrates that were made luminescent showed an excitation band at 388 nm and two emission bands at 452 nm and 515 nm. TPUR samples with greater AESA levels exhibited long‐persistent afterglow, whereas TPUR samples with lower AESA amounts exhibited rapid and reversible fluorescence when irradiated with ultraviolet light. Enhanced UV shielding and superhydrophobicity were observed in the photoluminescent plastic substrates upon increasing the phosphor content.