title: Self-assembling behavior of cellulose nanoparticles during freeze-drying: effect of suspension concentration, particle size, crystal structure, and surface charge.
abstract: Cellulose nanocrystals and cellulose nanofibers with I and II crystalline allomorphs (designated as CNC I, CNC II, CNF I, and CNF II) were isolated from bleached wood fibers by alkaline pretreatment and acid hydrolysis. The effects of concentration, particle size, surface charge, and crystal structure on the lyophilization-induced self-assembly of cellulose particles in aqueous suspensions were studied. Within the concentration range of 0.5 to 1.0 wt %, cellulose particles self-organized into lamellar structured foam composed of aligned membrane layers with widths between 0.5 and 3 μm. At 0.05 wt %, CNC I, CNF I, CNC II, and CNF II self-assembled into oriented ultrafine fibers with mean diameters of 0.57, 1.02, 1.50, and 1.00 μm, respectively. The size of self-assembled fibers became larger when more hydroxyl groups and fewer sulfates (weaker electrostatic repulsion) were on cellulose surfaces. Possible formation mechanism was inferred from ice growth and interaction between cellulose nanoparticles in liquid-crystalline suspensions.
authors.affiliation: School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, Louisiana 70803, United States.
authors.forename: Jingquan
authors.initials: J
authors.lastname: Han
authors.forename: Chengjun
authors.initials: C
authors.lastname: Zhou
authors.forename: Yiqiang
authors.initials: Y
authors.lastname: Wu
authors.forename: Fangyang
authors.initials: F
authors.lastname: Liu
authors.forename: Qinglin
authors.initials: Q
authors.lastname: Wu
mesh_terms: D002482:Cellulose / Q000737:chemistry* / Q000302:isolation & purification; D005612:Freeze Drying; D006868:Hydrolysis; D046529:Microscopy, Electron, Transmission; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D055672:Static Electricity; D013499:Surface Properties; D013535:Suspensions; D014867:Water / Q000737:chemistry*; D014934:Wood / Q000737:chemistry
chemical_list: D013535:Suspensions; D014867:Water; D002482:Cellulose