Effect of Polymer Adsorption State on the Properties of Poly(ethylene glycol)/Cellulose Nanocrystal Composites

Cellulose nanocrystals (CNCs) are renewable rod-like nanomaterials with high stiffness, a large aspect ratio, and abundant surface hydroxyl groups, enabling strong interactions with polymer chains. In polymer/CNC composite systems, polymer chains can adsorb onto CNC surfaces to form interfacial adsorption layers. However, adsorption is not solely determined by polymer chemistry; it is also strongly influenced by the solvent environment and processing history. Consequently, composites with identical compositions may develop different interfacial structures, yet the implications of these differences for macroscopic material properties remain poorly understood.

In this study, Poly(ethylene glycol) (PEG) is used as a model polymer to investigate the relationship between solvent-dependent adsorption behavior and the properties of PEG/CNC composites. Two preparation routes are compared. In aqueous suspensions, PEG exhibits little adsorption onto CNC surfaces, and adsorption occurs primarily during solvent evaporation. In contrast, under solvent conditions that promote PEG–CNC interactions, adsorption is established in the suspension state prior to drying. These contrasting adsorption pathways enable a direct investigation of how adsorption history influences the evolution of composite structure.

The resulting materials are characterized by rheological strain sweep and frequency sweep measurements to evaluate their viscoelastic properties. By directly comparing composites prepared with different adsorption histories, this study elucidates how solvent-controlled polymer adsorption influences the structure–property relationship of CNC-based composites.

The findings provide fundamental insight into the role of polymer adsorption in determining composite performance and demonstrate a strategy for tailoring material properties through the control of interfacial interactions during processing.