title: Grafting poly(methyl methacrylate) onto polyimide nanofibers via "click" reaction.
abstract: Surface modification of azide-decorated polyimide (PI) nanofibers with well-defined alkyne-terminated poly(methyl methacrylate) (PMMA) was accomplished via the combination of atom transfer radical polymerization (ATRP) and "click" chemistry. In this work, PI nanofibers were prepared via electrospun polyamic acid (PAA), followed by thermal imidization. Grafting of PMMA onto PI nanofibers was accomplished in three steps: (1) choloromethylation and azidization of PI nanofibers; (2) preparation of alkyne-terminated PMMA by ATRP of methyl methacrylate in toluene using propargyl 2-bromopropionate as initiator; (3) click coupling between the azidized PI nanofibers and the alkyne-terminated PMMA under the catalysis of Cu(I)Br/N,N,N',N''-pentamethyldiethylenetriamine (PMDETA). Gel permeation chromatography (GPC), (1)H NMR, and Fourier transform infrared (FT-IR) all confirmed the structure of alkyne-terminated poly(methyl methacrylate). The modified surface was characterized by X-ray photoelectron spectroscopy (XPS) after each modification stage. XPS and scanning electron microscope (SEM) were utilized to confirm PMMA-functionalized PI nanofibers, showing polymer coatings present on the surface of PI nanofibers. PI-g-PMMA nanofibers exhibited a more significant reinforcing effect compared to that with ungrafted PI nanofibers.
authors.affiliation: State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China.
authors.forename: Zhenjun
authors.initials: Z
authors.lastname: Chang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xu
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zhang
authors.forename: Dajun
authors.initials: D
authors.lastname: Chen