Preparation And Characterization Of Structure-Controllable Cellulose Functional Materials

Cellulose is the most abundant and renewable biopolymer provided by nature; it is a kind of cheap and nontoxic raw material for various applications. The processing of cellulose is restricted by its limited solubility in common solvents and its inability to melt because of its numerous intermolecular and intramolecular hydrogen bonding. Green solvent - room temperature ionic liquids (RTILs) was found to be a powerful solvent for cellulose.With the increasing demand to use cellulose more effectively, modification of cellulose by grafting copolymerization provides a significant route to combine the advantages of natural and synthetic macromolecules with wide range of potential applications. The macroinitiator was synthesized by direct homogenous acylation of cellulose in an ionic liquid 1-Allyl-3-methylimidazolium Chloride (AMIMCl) in absence of any catalyst and protecting group chemistry. Then the macroinitiator can be dissolved in N,N-dimethyl-formamide (DMF) pretty well, and homogeneous Atom Transfer Radical Polymerization (ATRP) from cellulose macroinitiator can take place. The grafting copolymers were characterized by means of gravimetry, 1H NMR, FT-IR and TGA measurements. The UV and DLS investigations show that aggregates formed by the novel copolymers in water exhibit clearly thermo-responding in accordance with the change of temperature. The copolymers were found to form discrete, spherical particles in water as observed by tapping mode AFM and TEM.More recently, there is an increased use of cellulose micro/nanomaterials in developing new and inexpensive biodegradable materials due to low weight, low cost, lack of abrasiveness during processing. Electrospinning is one of the most important tools of nanotechnology. This technique is applied to cellulose/RTILs system. By changing the concentration of polymer solution with DMF, both nanofibers and nanoparticles can be easily produced. Also magnetic nanoparticles - magnetite Fe3O4 and fluorescent material- carbazol-9-ylacetic acid can be ground into the solution to prepare uniform cellulose beads displaying magetic fluorescent properties.