Water Effects on Molecular Adsorption of Poly(N-vinyl-2-pyrrolidone) on Cellulose Nanocrystals Surfaces: Molecular Dynamics Simulations.

Darya Gurina,Oleg Surov,Anatoly Zakharov,Marina Voronova,Mikhail Kiselev

doi:10.3390/ma12132155

Abstract

Models of interaction between a poly(N-vinyl-2-pyrrolidone) macromolecule and a fragment of Iβ-cellulose were built in a vacuum and water environment. The models were made to interpret the mechanism of interaction of the polymer and cellulose nanocrystals by the classical molecular dynamics method. The structural behavior of a poly(N-vinyl-2-pyrrolidone) macromolecule in water has been studied in terms of the radius of gyration, atom–atom radial distribution functions and number of hydrogen bonds. It was found that the polymer has a high affinity with the solvent and each monomer unit has on average 0.5 hydrogen bonds. The structural and energy characteristics of the polymer adsorption were investigated at different initial positions of the poly(N-vinyl-2-pyrrolidone) macromolecule relative to the cellulose fragment. It was observed that the polymer macromolecule was mainly adsorbed on the cellulose fragment in the globular form. Moreover, in the solvent the interaction of poly(N-vinyl-2-pyrrolidone) with the cellulose hydrophobic surface was stronger than that with the hydrophilic one. This study will show that the presence of water makes the interaction between the polymer and cellulose weaker than in a vacuum, and the polymer and cellulose mainly interact through their solvation shells.

Highlights

Cellulose is the most abundant available renewable polymer resource
In order to understand the structural behavior of the polymer in the solvent, we calculated the radius of gyration (Rg ) which is one of the important quantities in conformational statistics of polymer chains depending on the molecular weight of the macromolecule, on its constitution, and on the extent to which it is swollen by the solvent
The paper considers the interaction of PVP with both types of cellulose surfaces—hydrophobic and hydrophilic ones

Summary

Introduction

Cellulose is the most abundant available renewable polymer resource. Cellulose is well known as a raw material used in a wide spectrum of materials and products. Cellulose fibrils are structural entities formed through cellulose biogenesis, stabilized by van der Waals forces and hydrogen bonds. The fibrils can be separated from a cellulose source into amorphous and crystalline components by enzymatic, chemical, mechanical processes or their combination, yielding cellulose nanofibrils (CNF). CNC are the subject of a plethora of studies in the development of coating components, rheology modifiers, stabilizers of multiphase systems, optical devices, and nanocomposites reinforcement, owing to the CNC nanoscale dimensions, light weight, morphology, and self-assembly behavior [1,2,3,4].

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