Highly Modified Cellulose Nanocrystals and Formation of EpoxyNanocrystalline Cellulose (CNC) Nanocomposites

摘要

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 C-13 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 nano and 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.