title: Towards biomimicking wood: fabricated free-standing films of Nanocellulose, Lignin, and a synthetic polycation.
abstract: Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and lignin. Layer-by-layer (LbL) assembly process which relies on the assembly of oppositely charged molecules from aqueous solutions was used to build a freestanding composite film of isolated wood polymers of lignin and oxidized nanofibril cellulose (NFC). To facilitate the assembly of these negatively charged polymers, a positively charged polyelectrolyte, poly(diallyldimethylammomium chloride) (PDDA), was used as a linking layer to create this simplified model cell wall. The layered adsorption process was studied quantitatively using quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry. The results showed that layer mass/thickness per adsorbed layer increased as a function of total number of layers. The surface coverage of the adsorbed layers was studied with atomic force microscopy (AFM). Complete coverage of the surface with lignin in all the deposition cycles was found for the system, however, surface coverage by NFC increased with the number of layers. The adsorption process was carried out for 250 cycles (500 bilayers) on a cellulose acetate (CA) substrate. Transparent free-standing LBL assembled nanocomposite films were obtained when the CA substrate was later dissolved in acetone. Scanning electron microscopy (SEM) of the fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle (PDDA-Lignin-PDDA-NC) was estimated to be 17 nm for two different lignin types used in the study. The data indicates a film with highly controlled architecture where nanocellulose and lignin are spatially deposited on the nanoscale (a polymer-polymer nanocomposites), similar to what is observed in the native cell wall.
authors: Institute for Critical Technology and Applied Science, Virginia Tech; Macromolecules and Interfaces Institute, Virginia Tech; Institute for Food Safety and Health, Illinois Institute of Technology- Moffett Campus.
authors: Karthik
authors: K
authors: Pillai
authors: Macromolecules and Interfaces Institute, Virginia Tech; Wood, Cellulose, and Paper Research Department, University of Guadalajara.
authors: Fernando
authors: F
authors: Navarro Arzate
authors: Macromolecules and Interfaces Institute, Virginia Tech; Department of Sustainable Biomaterials, Virginia Tech.
authors: Wei
authors: W
authors: Zhang
authors: Institute for Critical Technology and Applied Science, Virginia Tech; Macromolecules and Interfaces Institute, Virginia Tech; Department of Sustainable Biomaterials, Virginia Tech; Sustainable Nanotechnology Interdisciplinary Graduate Education Program, Virginia Tech; srenneck@vt.edu.
authors: Scott
authors: S
authors: Renneckar
mesh_terms: D000498:Allyl Compounds / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D008031:Lignin / Q000737:chemistry*; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force / Q000379:methods; D011073:Polyamines / Q000737:chemistry; D000071228:Polyelectrolytes; D058525:Quartz Crystal Microbalance Techniques / Q000379:methods; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D014934:Wood / Q000737:chemistry*
chemical_list: D000498:Allyl Compounds; D002482:Cellulose; D008031:Lignin; D008567:Membranes, Artificial; D011073:Polyamines; D000071228:Polyelectrolytes; D000644:Quaternary Ammonium Compounds; C508190:diallyldimethylammonium chloride