Aligned regenerated cellulose films with enhanced mechanical and optical properties for light management

Abstract

The dissolution of cellulose endows the green and environmentally friendly cellulosic material with a wide range of processing properties, further enhancing its advantages as a basic material. However, its unsatisfactory mechanical performance and functionality severely limited its practical application. Herein, a facile molecular orientation strategy was developed to orient the aggregated structure of the dissolved cellulose in the lithium chloride/N,N-dimethylacetamide system and to obtain high-performance films. During the preparation process, cross-linking, stretching, and hot pressing were utilized to anchor, orient, and fix the orientated structure of the cellulose molecular chains. Morphological analysis confirmed that the present process can produce an oriented microstructure of cellulose films with remarkable mechanical and optical properties. The optimal film obtained with a stretching ratio of 50 % exhibited a high mechanical strength of 145.9 MPa, and a high light transmittance of 86.2 %. Compared to the unstretched sample, the stretched films showed higher thermal stability, much higher mechanical strength (up to 169 % of the pure cellulose film), and stronger light polarization and scattering response. The present strategy, based on the regulation of cellulose aggregate structure, provides a promising approach for the development of advanced regenerated cellulose materials with excellent performance and multifunctional properties.