Synthesis and electrospinning of well-defined polymer brushes by modification of polyacrylonitrile

As one of the most important precursors, polyacrylonitrile (PAN) and its functionality gained extensive attention but faced challenges in the preparation of nanofiber by electrospinning technology. Herein, poly(acrylonitrile-g-ethylene alcohol) (PAN-g-PEG) were succussfuly synthesized by the modification of PAN, using the methods of Click Chemistry and Mitsunobu reaction sequentially. Firstly, well-defined PAN was prepared by Cu(0)-mediated controlled/living radical polymerization with a molar ratio of [AN]0:[EBiB]0:[Cu]0:[TEMED]0 = 500:1:1:2. Tetrazole-containing PAN was then successfully modified by nitrile-Click Chemistry, which sodium azide and ammonium chloride was used as substrate and catalyst, respectively. Using Mitsunobu reaction, PAN-g-PEG was obtained from tetrazole-containing PAN and poly(ethyl alcohol) with the catalyst of diethyl azodicarboxylate and triphenylphosphine. After typical characterization, PAN-g-PEG nanofiber with the average diameter around 90 nm, was successfully prepared by electrospinning. The obtained PAN-g-PEG nanofiber has a smoother surface than PAN nanofiber, which suggests that a new modification approach of PAN nanofiber is successfully achieved.