Poly(methyl methacrylate)‐grafted cellulose nanocrystals: One‐step synthesis, nanocomposite preparation, and characterization

Abstract

Cellulose nanocrystals (CNCs) are ideal reinforcing agents for polymer nanocomposites because they are lightweight and nano‐sized with a large aspect ratio and high elastic modulus. To overcome the poor compatibility of hydrophilic CNCs in non‐polar composite matrices, we grafted poly(methyl methacrylate) (PMMA) from the surface of CNCs using an aqueous, one‐pot, free radical polymerization method with ceric ammonium nitrate as the initiator. The hybrid nanoparticles were characterized by CP/MAS NMR, X‐ray photoelectron spectroscopy, infrared spectroscopy, contact angle, thermogravimetric analysis, X‐ray diffraction, and atomic force microscopy. Spectroscopy demonstrates that 0.11 g/g (11 wt %) PMMA is grafted from the CNC surface, giving PMMA‐g‐CNCs, which are similar in size and crystallinity to unmodified CNCs but have an onset of thermal degradation 45 °C lower. Nanocomposites were prepared by compounding unmodified CNCs and PMMA‐g‐CNCs (0.0025–0.02 g/g (0.25–2 wt %) loading) with PMMA using melt mixing and wet ball milling. CNCs improved the performance of melt‐mixed nanocomposites at 0.02 g/g (2 wt %) loading compared to the PMMA control, while lower loadings of CNCs and all loadings of PMMA‐g‐CNCs did not. The difference in Young's modulus between unmodified CNC and polymer‐grafted CNC composites was generally insignificant. Overall, ball‐milled composites had inferior mechanical and rheological properties compared to melt‐mixed composites. Scanning electron microscopy showed aggregation in the samples with CNCs, but more pronounced aggregation with PMMA‐g‐CNCs. Despite improving interfacial compatibility between the nanoparticles and the matrix, the effect of PMMA‐g‐CNC aggregation and decreased thermal stability dominated the composite performance.

In Situ Semibatch Emulsion Polymerization of 2‐Ethyl Hexyl Acrylate/n‐Butyl Acrylate/Methyl Methacrylate/Cellulose Nanocrystal Nanocomposites for Adhesive Applications

“…Thus, when a polymer application calls for a more hydrophobic monomer to be used, surface modification of the CNCs may be required to improve latex–nanoparticle compatibility. Future work will include the use of modified CNCs with poly(methyl methacrylate) grafted from the surface, which could aid in the compatibility of CNCs in a polymer matrix . Another possibility is to use CNCs modified using tannic acid as a primer, followed by a reaction with decylamine.…”

Experimental methods in chemical engineering: Preface

“…published in 2016 and 2017. We identified and collated keywords that represent physical and physicochemical properties (pressure, temperature, time), instruments and derived properties (XRD, XPS, viscosity, pH), mathematical methods (CFD, tomography), and statistical tests, and experimental design like response surface methodologies . To illustrate relationships between the network data, we generated bibliometric maps with the VOSViewer software tool .…”

Electroosmotic dewatering of cellulose nanocrystals

“…On a laboratory scale, centrifugation is often used to increase the solid content during washing of the particles, however, the solid content is typically remains in the range 0.2-3 wt% (e.g. Á vila Ramírez et al 2017;Bai et al 2009;Cranston and Gray 2006;Kedzior et al 2016). Many industrial applications require that this solid content is increased and different drying methods, such as thermal, freeze and supercritical drying, can be used to obtain a dry material (Peng et al 2012(Peng et al , 2013.…”