title: Highly Transparent and Toughened Poly(methyl methacrylate) Nanocomposite Films Containing Networks of Cellulose Nanofibrils.
abstract: Cellulose nanofibrils (CNFs) are a class of cellulosic nanomaterials with high aspect ratios that can be extracted from various natural sources. Their highly crystalline structures provide the nanofibrils with excellent mechanical and thermal properties. The main challenges of CNFs in nanocomposite applications are associated with their high hydrophilicity, which makes CNFs incompatible with hydrophobic polymers. In this study, highly transparent and toughened poly(methyl methacrylate) (PMMA) nanocomposite films were prepared using various percentages of CNFs covered with surface carboxylic acid groups (CNF-COOH). The surface groups make the CNFs interfacial interaction with PMMA favorable, which facilitate the homogeneous dispersion of the hydrophilic nanofibrils in the hydrophobic polymer and the formation of a percolated network of nanofibrils. The controlled dispersion results in high transparency of the nanocomposites. Mechanical analysis of the resulting films demonstrated that a low percentage loading of CNF-COOH worked as effective reinforcing agents, yielding more ductile and therefore tougher films than the neat PMMA film. Toughening mechanisms were investigated through coarse-grained simulations, where the results demonstrated that a favorable polymer-nanofibril interface together with percolation of the nanofibrils, both facilitated through hydrogen bonding interactions, contributed to the toughness improvement in these nanocomposites.
authors.affiliation: Macromolecular Science & Technology Branch, U.S. Army Research Laboratory , Aberdeen Proving Ground, Maryland 21005, United States.|TKC Global Solutions, LLC , Aberdeen, Maryland 21005, United States.
authors.forename: Hong
authors.initials: H
authors.lastname: Dong
authors.affiliation: Macromolecular Science & Technology Branch, U.S. Army Research Laboratory , Aberdeen Proving Ground, Maryland 21005, United States.|TKC Global Solutions, LLC , Aberdeen, Maryland 21005, United States.
authors.forename: Yelena R
authors.initials: YR
authors.lastname: Sliozberg
authors.affiliation: Macromolecular Science & Technology Branch, U.S. Army Research Laboratory , Aberdeen Proving Ground, Maryland 21005, United States.
authors.forename: James F
authors.initials: JF
authors.lastname: Snyder
authors.affiliation: Macromolecular Science & Technology Branch, U.S. Army Research Laboratory , Aberdeen Proving Ground, Maryland 21005, United States.
authors.forename: Joshua
authors.initials: J
authors.lastname: Steele
authors.affiliation: Macromolecular Science & Technology Branch, U.S. Army Research Laboratory , Aberdeen Proving Ground, Maryland 21005, United States.
authors.forename: Tanya L
authors.initials: TL
authors.lastname: Chantawansri
authors.affiliation: Macromolecular Science & Technology Branch, U.S. Army Research Laboratory , Aberdeen Proving Ground, Maryland 21005, United States.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Orlicki
authors.affiliation: Macromolecular Science & Technology Branch, U.S. Army Research Laboratory , Aberdeen Proving Ground, Maryland 21005, United States.|TKC Global Solutions, LLC , Aberdeen, Maryland 21005, United States.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Walck
authors.affiliation: Forest Products Laboratory, USDA Forest Service , Madison, Wisconsin 53726, United States.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Reiner
authors.affiliation: Forest Products Laboratory, USDA Forest Service , Madison, Wisconsin 53726, United States.
authors.forename: Alan W
authors.initials: AW
authors.lastname: Rudie
mesh_terms: D002152:Calorimetry, Differential Scanning; D002482:Cellulose / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D043942:Nanotubes / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength
chemical_list: D002482:Cellulose; D019904:Polymethyl Methacrylate
keywords: cellulose nanofibrils; coarse-grained simulation; interfacial interactions; mechanical properties; nanocomposites; poly(methyl methacrylate)