Adjustment of Molecular Weight for a Cellulose-graft-poly(ethylene glycol dimethacrylate) Polymer Brush by Atom Transfer Radical Polymerization in an Ionic Liquid

A cellulose-graft-poly(ethylene glycol dimethacrylate) (cellulose-g-PEGDMA) molecule brush was synthesized by atom transfer radical polymerization in the ionic liquid 1-allyl-3methylimidazolium chloride. The controlled mechanism of the polymer brush size and polydispersity index (PDI, Mw/Mn) were investigated. The grafting copolymers were characterized by FTIR, H-1-NMR and GPC. The results indicate that the reaction time was the main factor to control the length of the cellulose-g-PEGDMA molecule brush. The ligand was the decisive factor in controlling the PDI of the molecule brush. The PDI of PEGDMA was precisely controlled at 1.1-1.4 by using pentamethyldiethylenetriamine(PMDETA) as the ligand. Moreover, the graft molecule brush length could be varied with the change of PMDETA concentration. The Mn of PEGDMA was 75210 and had a narrow PDI of 1.15 when the PMDETA/CuBr ratio was 20:1. In addition, TEM images show that the cellulose-g-PEGDMA copolymer could aggregate and selfassemble into a sphere-like polymeric structure in solution, indicating that the obtained grafting copolymers have potential applications in biomedical materials.