title: Functional and surface-active membranes from poly(vinylidene fluoride)-graft-poly(acrylic acid) prepared via RAFT-mediated graft copolymerization.
abstract: Poly (vinylidene fluoride) (PVDF) with "living" poly (acrylic acid) (PAAc) side chains (PVDF-g-PAAc) was prepared by reversible addition-fragmentation chain transfer (RAFT)-mediated graft copolymerization of acrylic acid (AAc) with the ozone-pretreated PVDF. The chemical composition and structure of the copolymers were characterized by elemental analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The copolymer could be readily cast into pH-sensitive microfiltration (MF) membranes with enriched living PAAc graft chains on the surface (including the pore surfaces) by phase inversion in an aqueous medium. The surface composition of the membranes was determined by X-ray photoelectron spectroscopy. The morphology of the membranes was characterized by scanning electron microscopy. The pore size distribution of the membranes was found to be much more uniform than that of the corresponding membranes cast from PVDF-g-PAAc prepared by the "conventional" free-radical graft copolymerization process. Most important of all, the MF membranes with surface-tethered PAAc macro chain transfer agents, or the living membrane surfaces, could be further functionalized via surface-initiated block copolymerization with N-isopropylacrylamide (NIPAAM) to obtain the PVDF-g-PAAc-b-PNIPAAM MF membranes, which exhibited both pH- and temperature-dependent permeability to aqueous media.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260.
authors.forename: L
authors.initials: L
authors.lastname: Ying
authors.forename: W H
authors.initials: WH
authors.lastname: Yu
authors.forename: E T
authors.initials: ET
authors.lastname: Kang
authors.forename: K G
authors.initials: KG
authors.lastname: Neoh
mesh_terms: D000180:Acrylic Resins / Q000138:chemical synthesis* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D015394:Molecular Structure; D010316:Particle Size; D011145:Polyvinyls / Q000138:chemical synthesis* / Q000737:chemistry*; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013499:Surface Properties; D013696:Temperature; D013818:Thermogravimetry; D005465:Fluorocarbon Polymers
chemical_list: D000180:Acrylic Resins; D008567:Membranes, Artificial; D011145:Polyvinyls; C518132:poly(vinylidene fluoride)-graft-poly(acrylic acid); C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers; C006903:carbopol 940