title: Colloidal ionic assembly between anionic native cellulose nanofibrils and cationic block copolymer micelles into biomimetic nanocomposites.
abstract: We present a facile ionic assembly between fibrillar and spherical colloidal objects toward biomimetic nanocomposites with majority hard and minority soft domains based on anionic reinforcing native cellulose nanofibrils and cationic amphiphilic block copolymer micelles with rubbery core. The concept is based on ionic complexation of carboxymethylated nanofibrillated cellulose (NFC, or also denoted as microfibrillated cellulose, MFC) and micelles formed by aqueous self-assembly of quaternized poly(1,2-butadiene)-block-poly(dimethylaminoethyl methacrylate) with high fraction of the NFC reinforcement. The adsorption of block copolymer micelles onto nanocellulose is shown by quartz crystal microbalance measurements, atomic force microscopy imaging, and fluorescent optical microscopy. The physical properties are elucidated using electron microscopy, thermal analysis, and mechanical testing. The cationic part of the block copolymer serves as a binder to NFC, whereas the hydrophobic rubbery micellar cores are designed to facilitate energy dissipation and nanoscale lubrication between the NFC domains under deformation. We show that the mechanical properties do not follow the rule of mixtures, and synergistic effects are observed with promoted work of fracture in one composition. As the concept allows wide possibilities for tuning, the work suggests pathways for nanocellulose-based biomimetic nanocomposites combining high toughness with stiffness and strength.
authors.affiliation: Department of Applied Physics, Aalto University, FIN-00076 Aalto, Espoo, Finland.
authors.forename: Miao
authors.initials: M
authors.lastname: Wang
authors.forename: Anna
authors.initials: A
authors.lastname: Olszewska
authors.forename: Andreas
authors.initials: A
authors.lastname: Walther
authors.forename: Jani-Markus
authors.initials: JM
authors.lastname: Malho
authors.forename: Felix H
authors.initials: FH
authors.lastname: Schacher
authors.forename: Janne
authors.initials: J
authors.lastname: Ruokolainen
authors.forename: Mikael
authors.initials: M
authors.lastname: Ankerfors
authors.forename: Janne
authors.initials: J
authors.lastname: Laine
authors.forename: Lars A
authors.initials: LA
authors.lastname: Berglund
authors.forename: Monika
authors.initials: M
authors.lastname: Osterberg
authors.forename: Olli
authors.initials: O
authors.lastname: Ikkala
mesh_terms: D000327:Adsorption; D000838:Anions / Q000737:chemistry / Q000378:metabolism; D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000378:metabolism; D040761:Biomimetic Materials / Q000138:chemical synthesis* / Q000378:metabolism; D002412:Cations / Q000737:chemistry / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry*; D019563:Mechanics; D008689:Methacrylates / Q000737:chemistry*; D008823:Micelles; D018625:Microscopy, Atomic Force; D053761:Nanocomposites / Q000737:chemistry*; D057139:Nanofibers / Q000737:chemistry*; D055672:Static Electricity; D013718:Tensile Strength; D014867:Water / Q000737:chemistry
chemical_list: D000838:Anions; D001672:Biocompatible Materials; D002412:Cations; D003102:Colloids; D008689:Methacrylates; D008823:Micelles; D014867:Water; D002482:Cellulose