Nanocomposites Assembled via Electrostatic Interactions between Cellulose Nanocrystals and a Cationic Polymer

A facile approach to modify cellulose nanocrystal for the adsorption of perfluorooctanoic acid

Cellulose-based materials are a sustainable alternative to polymers derived from petroleum. Cellulose nanocrystal (CNC) is a biopolymer belonging to this family; it is commonly known for its important physical and chemical properties and ability to form a film. Modifying CNC via electrostatic interaction provided by cationic polymers is a facile and promising technique to enlarge the application of CNC. Herein, we report the preparation of films, from blends of negatively charged CNC and positively charged poly (trimethyl aminoethyl methacrylate) (PTMAEMA). The interaction between CNC and PTMAEMA was verified by using a quartz crystal microbalance with dissipation monitoring (QCM-D), as well as by measuring the particle size and ζ-potential of the casting mixture. To favor the application of the nanocomposite film in water treatment, the film was supported on Whatman™ paper, and adsorption tests were conducted using perfluorooctanoic acid (PFOA) as a model compound for the family of persistent fluorinated pollutants known as PFAS (per- and polyfluoroalkyl substances).

Cathodic electrodeposition of organic nanocomposite coatings reinforced with cellulose nanocrystals

A systematic examination of the structure-property relations to create nanocomposite coatings via electrophoretic deposition (EPD) of a cathodic polymer - for instance, polyacrylate - reinforced with cellulose nanocrystals (CNCs) is discussed in this work. EPD, a scalable and green technique, has also been used in our approach to polymerize dopamine in the presence of CNCs and cathodic polymer to improve adhesion properties. This study investigated the interactions between CNCs, polydopamine (PDA) and the cathodic polyacrylic polymer to elucidate the dispersion state of the nanoparticles in the system by carefully examining ζ-potential, particle size, and electrophoretic mobility dependence in the colloidal suspension. We examined the morphology and structure of the electrodeposited nanocomposites using SEM and XPS, and the results indicate the formation of a compact, homogeneous structure. The incorporation of CNCs or PDA introduces different levels of roughness to the surface as revealed by AFM. Our results indicate improved adhesion, as determined by bond strength, using CNCs (>20%) or CNC-PDA (>30%) relative to the cathodic polymer, as well as significant improvement in hardness. The technique and materials used show promise to develop industrial organic coatings with low emissions for applications in automotive coatings and other applications.

Dispersibility Characterization of Cellulose Nanocrystals in Polymeric-Based Composites

Cellulose nanocrystals (CNCs) are hydrophilic nanoparticles extracted from biomass with properties and functions different from cellulose and are being developed for property-oriented applications such as high stiffness, abundant active groups, and biocompatibility. It has broad application prospects in the field of composite materials, while the dispersibility of the CNC in polymers is the key to its application performance. Many reviews have discussed in-depth the modification strategies to improve the dispersibility of the CNC and summarized all characterization for the CNC, but there are no reviews on the in-depth exploration of dispersion characterization. This review is a comprehensive summary of the characterization of CNC dispersion in the matrix in terms of direct observation, indirect evaluation, and quantified evaluation, summarizing how and why different characterization tools reveal dispersibility. In addition, "decision tree" flowcharts are presented to provide the reader with a reference for selecting the appropriate characterization method for a specific composite.