Simultaneous Chemical and Optical Patterning of Polyacrylonitrile Film by Vapor-Based Reaction

Abstract

The surface of polyacrylonitrile (PAN) film is treated with ethyleneamines (EDA) in a simple chemical vapor phase reaction. Successful introduction of amine functional groups on the cyano group of PAN backbone is verified by FT-IR and NMR measurements. Further UV-vis and photoluminescence analyses show a red shift of the emission peak after repeated EDA treatment, which might be attributed to the formation of imine conjugation from newly formed carbon-nitrogen bonds on the PAN backbone. Further confocal laser scanning microscopy reveals that selective patterning of EDA on PAN films is possible via local polydimethylsiloxane masking. The results indicate that both chemical and optical patterning on PAN film can be realized via a single reaction and show the potential of this novel methodology in selective patterning.

Mass Production of Functional Amine–Conjugated PAN Nanofiber Mat via Syringeless Electrospinning and CVD

“…This chemical reaction between CN of PAN nanofibers and amine of EDA molecule could be found in FT‐IR spectra of E.PANs and pristine PAN nanofiber. Figure shows the FT‐IR spectra of E.PAN nanofibers depending on their reaction temperature and pristine PAN nanofiber, which are well matched with our previous works that use PAN nanoparticle and film . In all spectra, the FT‐IR absorbance peak of pristine PAN was verified as CN stretching bonds at 2250 cm −1 , CH stretching at 2872 cm −1 , and CH deformation at 1446 cm −1 , implying that the CVD reaction was surface selective.…”

“…To introduce the chemically reactive functional groups on the surface of electrospun PAN nanofiber mat, the CVD ( Scheme ) can be a good candidate as a simple treatment method. In general, solution‐based surface treatments such as pinner synthesis have been often used to adjust the surficial functional groups on the nanofiber . However, despite these solution‐based surficial treatments have good selectivity, there are several disadvantages: first, the process can destruct the morphology of nanofiber web because the solution‐based treatments must be accompanied with stirring the solution, and second, the process can limit some material diversity—for instance, to successfully accomplish the solution‐based process, selective solvent should be provided to dissolve only the reactants.…”

“…It is also possible to confirm the chemical conjugation of the CN of PAN nanofiber with amine of EDA molecule via fluorescence of E.PAN under UV light . To investigate the fluorescence properties of PAN nanofibers, optical images of PAN nanofibers under white light and UV light were collected ( Figure ).…”

“…To obtain the CVD‐treated electrospun PAN nanofiber, the as‐spun PAN nanofiber mat was cut into 8 cm × 3 cm, and then, it was put into the properly designed apparatus. After that, the inside of the apparatus was made as a vacuum state, and 0.1 mL of EDA was injected into the apparatus without contacting with the nanofiber . To vaporize the EDA molecule and to promote the chemical reaction between the molecule and nanofiber web, the reaction temperature was controlled as 80 and 100 °C for 2 h. After the CVD process, the EDA‐treated PAN nanofiber sheet (E.PAN) was dried to remove the residual EDA in the 80 °C oven for 1 h. In order to investigate the stability of the EDA layer on the E.PAN nanofibers, the E.PAN nanofibers were stored in ethanol and water, respectively, with shaking for 24 h. After that, the nanofibers were dried in an 80 °C drying oven for 24 h to remove the residual ethanol and water.…”

“…Meanwhile, although the increase of production rate provides great chance to produce nanofiber structures in large quantity, it is still difficult to produce the nanofiber webs using polymers having high amounts of useful functional groups and the high mechanical strength because, in general, the solubility of highly functionalized polymer and engineering polymers, which have high mechanical strength, are quite low. Here, we tried to produce nanofiber webs containing large amounts of functional groups and high mechanical properties with large quantity using syringeless electrospinning and sequential chemical vapor deposition (CVD) methods . Initially, PAN nanofibers were produced by the syringeless electrospinning with systematic investigation for optimized processing, and sequentially CVD with multiamine compounds was carried out to evaluate the useful functional groups on the surface and to enhance the mechanical properties.…”