Understanding the Structure and Dynamics of Nanocellulose-Based Composites with Neutral and ionic Poly(methacrylate) Derivatives using Inelastic Neutron Scattering and DFT Calculations.

Carla Vilela,Pedro D Vaz,Carmen S R Freire,Catarina Araújo,Paulo J A Ribeiro-Claro,Mariela M Nolasco,Armando J D Silvestre,Svemir Rudić

doi:10.3390/molecules25071689

Abstract

Bacterial nanocellulose (BC)-based composites containing poly(2-hydroxyethyl methacrylate) (PHEMA), poly(methacroylcholine chloride) (PMACC) or poly(methacroylcholine hydroxide) (PMACH) were characterized by inelastic neutron scattering (INS) spectroscopy, combined with DFT (density functional theory) calculations of model systems. A reasonable match between calculated and experimental spectral lines and their intensities was used to support the vibrational assignment of the observed bands and to validate the possible structures. The differences between the spectra of the nanocomposites and the pure precursors indicate that interactions between the components are stronger for the ionic poly(methacrylate) derivatives than for the neutral counterpart. Displaced anions interact differently with cellulose chains, due to the different ability to compete with the O–H···O hydrogen bonds in cellulose. Hence, the INS is an adequate technique to delve deeper into the structure and dynamics of nanocellulose-based composites, confirming that they are true nanocomposite materials instead of simple mixtures of totally independent domains.

Highlights

A tour through the kaleidoscopic portfolio of materials developed in the last decades, clearly shows that composite materials based on cellulose [1], and bacterial nanocellulose (BC) in particular [2], are quite relevant for myriad domains of applications [3,4,5]
One of the techniques that is gaining momentum to characterize the structure of bulk materials at a molecular level is inelastic neutron scattering (INS) spectroscopy, which provides a unique assessment of the structural dynamics of hydrogenous materials that is not always possible by its optical counterparts, namely infrared and
BCPHEMA and BCPMACC nanocomposites with two different polymer contents (Table 1) were prepared by the simple in-situ free radical polymerization of the respective monomers, namely HEMA and MACC (Figure 1), within the Bacterial nanocellulose (BC) porous network, according to the procedures reported in our previous studies [44,45]

Summary

Introduction

A tour through the kaleidoscopic portfolio of materials developed in the last decades, clearly shows that composite materials based on cellulose [1], and bacterial nanocellulose (BC) in particular [2], are quite relevant for myriad domains of applications [3,4,5]. (metha)acrylate functional groups, is a simple top-down method that promotes the use of BC without altering its valuable and unique three-dimensional structure [2]. Phosphate [32], are examples of (meth)acrylic monomers that have already been dispersed and polymerized into the BC network, originating materials with the most assorted properties. The fundamental understanding of the interactions between the individual components in nanocomposites is of paramount importance to withdraw structure-property correlations that can contribute to optimize and modulate the properties of the resulting materials and, surpass the scientific and technological challenges associated with their production. One of the techniques that is gaining momentum to characterize the structure of bulk materials at a molecular level is inelastic neutron scattering (INS) spectroscopy, which provides a unique assessment of the structural dynamics of hydrogenous materials that is not always possible by its optical counterparts, namely infrared and

Methods

Results

Conclusion