title: Chemical and nanomechanical analysis of rice husk modified by ATRP-grafted oligomer.
abstract: Rice husk (RH), an abundant agricultural residue, was reacted with 2-bromoisobutyryl bromide, to convert it to a heterogeneous polyfunctional macroinitiator for Atom Transfer Radical Polymerization (ATRP). The number of active sites placed on the RH surface was small, but they were ATRP active. Non-polar methyl methacrylate (MMA) and polar acrylonitrile (AN) were polymerized from the RH, and a sequential monomer addition was used to prepare an amphiphilic PMMA-b-PAN copolymer on RH surface. FTIR qualitatively confirmed the grafting. Gravimetric and XPS analysis of the different RH surface compositions indicated thin layers of oligomeric PMMA, PAN, and PMMA-b-PAN. The modified surfaces were mapped by nanomechanical AFM to measure surface roughness, and adhesion and moduli using the Derjaguin-Muller-Toropov model. RH grafted with MMA possessed a roughness value of 7.92, and a hard and weakly adhering surface (13.1 GPa and 16.7 nN respectively) while RH grafted with AN yielded a roughness value of 29 with hardness and adhesion values of 4.0 GPa and 23.5 nN. The PMMA-b-PAN modification afforded a surface with a roughness value of 51.5 nm, with hardness and adhesion values of 3.0 GPa and 75.3 nN.
authors.affiliation: Department of Chemistry, Michigan Technological University, 1400 Townsend Ave., Houghton, MI 49931, USA. smchemist@yahoo.com
authors.forename: Samir M
authors.initials: SM
authors.lastname: Morsi
authors.forename: Anahita
authors.initials: A
authors.lastname: Pakzad
authors.forename: Amal
authors.initials: A
authors.lastname: Amin
authors.forename: Reza S
authors.initials: RS
authors.lastname: Yassar
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Heiden
mesh_terms: D000181:Acrylonitrile / Q000138:chemical synthesis* / Q000737:chemistry; D008768:Methylmethacrylates / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D012275:Oryza / Q000737:chemistry*; D010316:Particle Size; D058105:Polymerization; D013499:Surface Properties
chemical_list: D008768:Methylmethacrylates; D000181:Acrylonitrile