Breaking and Connecting: Highly Hazy and Transparent Regenerated Networked-Nanofibrous Cellulose Films via Combination of Hydrolysis and Crosslinking

High optical transparency combined with high optical haze are essential requirements for optoelectronic substrates. Light scattering caused by haze is responsible for increasing light harvesting in photon-absorbing active materials, hence increasing efficiencies. A trade-off between transparency and haze is common in solar substrates with high transparency (similar to 90%) and low optical haze (similar to 20%), or vice versa. In this study, we report a novel, highly transparent film fabricated from regenerated cellulose after controlled acid-hydrolysis of microcrystalline cellulose (MCC). The developed networked-nanofibrous cellulose was chemically crosslinked with glutaraldehyde (GA) and vacuum-cured to facilitate the fabrication of mechanically stable films. The effects of crosslinker concentration, crosslinking time, and curing temperature were investigated. Optimum conditions for fabrication unveils high optical transparency (similar to 94%) and high haze (similar to 60%), using 25% GA for 24 hr with a curing temperature of 25 degrees C; therefore, conveying an optimal substrate for optoelectronics applications. The high haze arises primarily from the crystalline, networked crystals of cellulose II structure formed within the regenerated cellulose upon hydrolysis. Moreover, the developed crosslinked film presents high thermal stability, water resistance, and good mechanical resilience. This high-performance crosslinked cellulose film can be considered a potential material for new environmentally-friendly optical substrates.

Automated summary

This study reports a novel highly transparent film fabricated from regenerated cellulose, which exhibits high optical haze and excellent thermal stability, water resistance, and mechanical resilience. The film has potential applications as environmentally-friendly optical substrates.