Mild and Versatile Functionalization of Nacre-Mimetic Cellulose Nanofibrils/Clay Nanocomposites by Organocatalytic Surface Engineering.

Rana Alimohammadzadeh,Armando Córdova,Lars A Berglund,Lilian Medina,Luca Deiana

doi:10.1021/acsomega.0c00978

Rana Alimohammadzadeh, Armando Córdova + Show 3 more

Open Access

https://doi.org/10.1021/acsomega.0c00978

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Abstract

Development of surface-engineering strategies, which are facile, versatile, and mild, are highly desirable in tailor-made functionalization of high-performance bioinspired nanocomposites. We herein disclose for the first time a general organocatalytic strategy for the functionalization and hydrophobization of nacre-mimetic nanocomposites, which includes vide supra key aspects of surface engineering. The merging of metal-free catalysis and the design of nacre-mimetic nanocomposite materials were demonstrated by the organocatalytic surface engineering of cellulose nanofibrils/clay nanocomposites providing the corresponding bioinspired nanocomposites with good mechanical properties, hydrophobicity, and useful thia-, amino, and olefinic functionalities.

Highlights

Nature has the ability of producing lightweight materials with robust stability and excellent properties from simple building blocks
The fabricated MTM/cellulose nanofibrils (CNFs) clay nanopaper composites are prepared by scalable vacuum-filtration and drying procedures similar to paper-making (Figure 1a)
The mixed MTM and CNF suspension shows optical transparency; the filtration is relatively fast in the beginning but slows down as the MTM/ CNF nanocomposite film starts to form on top of the filtration membrane

Summary

Introduction

Nature has the ability of producing lightweight materials with robust stability and excellent properties from simple building blocks. Material scientists and engineers have gathered important lessons from nature on fabrication of lightweight materials with exceptional properties.[1−3] In this context, nacre has gained significant research interest because it has exceptional stability and excellent properties derived from its unique brick-and-mortar structure, which comprises wellaligned inorganic platelets “glued” together by an organic matrix (chitin and proteins).[4−6] Despite the many types of inorganic “bricks”, which have been investigated when mimicking the nacre’s brick-and-mortar structure, the present research is on clay platelets of nanometer thickness.[7−11] Clay is useful in reinforcing other types of composites.[12,13] In seminal work, Kotov and co-workers introduced a general concept of nacre-mimetic materials for clay nanoplatelet-neat polymer systems.[7] It is based on forming micron-thick films by sequential deposition of clay and polyelectrolytes Another ground-breaking work is the introduction of cross-linking to reach excellent material properties with unprecedented levels of Young’s modulus (>100 GPa).[8] A novel core-shell approach was introduced by Walther and co-workers.[13,14] Here, a polymer is absorbed on the clay nanoplatelets and subsequently the nonsorbing polymer is removed by centrifugation. An elegant and sustainable approach for constructing nacremimetic nanocomposite systems using cellulose nanofibrils (CNFs) as the renewable mortar instead of fossil-based polymers such as PVA and PDDA was introduced.[15−22] The CNFs, which are the primary reinforcement component in the wood cell wall, have been derived from delignified wood pulp fibers and provide good mechanical properties to lightweight

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