Highly Modified Cellulose Nanocrystals and Formation of Epoxy-Nanocrystalline Cellulose (CNC) Nanocomposites

Abstract

This work presents an environmentally friendly, iodine-catalyzed chemical modification method to generate highly hydrophobic, optically active nanocrystalline cellulose ({CNC}). The high degree of ester substitution ({DS} = 2.18), hydrophobicity, crystalline behavior, and optical activity of the generated acetylated {CNC} (Ac-{CNC}) were quantified by {TEM}, {FTIR}, solid 13C {NMR}, contact angle, {XRD}, and {POM} analyses. Ac-{CNC} possesses substantial enhancement in thermal stability (16.8%) and forms thin films with an interlayer distance of 50−150 nm, presenting cavities suitable for entrapping nanoand microparticles. Generated Ac-{CNC} proved to be an effective reinforcing agent in hydrophobic polymer matrices for fabricating high performance nanocomposites. When integrated at a very low weight percentage (0.5%) in an epoxy matrix, {AcCNC} provided for a 73% increase in tensile strength and a 98% increase in modulus, demonstrating its remarkable reinforcing potential and effective stress transfer behavior. The method of modification and the unique properties of the modified {CNC} (hydrophobicity, crystallinity, reinforcing ability, and optical activity) render them a novel bionanomaterial for a range of multipurpose applications.