Anisotropy and Nanomechanics of Cellulose Nanocrystals/Polyethylene Glycol Composite Films

• Published in: Biomacromolecules Vol. 23; no. 4; pp. 1592 - 1600
• Main Authors: Rajeev, Ashna, Natale, Giovanniantonio
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.04.2022
• Subjects: Anisotropy; Cellulose - chemistry; Nanoparticles - chemistry; Polyethylene Glycols - chemistry; Suspensions
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/acs.biomac.1c01392

The influence of shear flow on the nanomechanical properties of cellulose nanocrystal (CNC)/polyethylene glycol (PEG) composite films and the distribution of anisotropic phases are investigated at various CNC/PEG ratios. Here, the drying process of CNC/PEG mixed suspensions is systematically traced by rheology, followed by the spatial mapping of local mechanical properties of CNC/PEG films by nanoindentation. The detailed study of the morphology of CNC/PEG films by polarized optical microscopy (POM) and image analysis revealed the link between the mechanical properties and the influence of shear flow. A comparison of the data obtained for shear-dried films with nonsheared films showed the improved reduced Young’s modulus (E r) and hardness (H), and suppression of microphase separation in the shear-dried films. Based on this experimental evidence, a mechanism is proposed to explain the microstructural transition during the shear-drying process leading to the generation of the anisotropic domains containing the shear-induced assembled structure of CNC particles coexisting with the elongated PEG microphases.