Polymer Tubes with Longitudinal Composition Gradient by Face-to-Face Wetting

Abstract

Nanoporous and macroporous templates were simultaneously infiltrated from both of their opposite surfaces using model polymers labeled with fluorescent probes or bearing probe molecules detectable by energy-dispersive X-ray spectroscopy by precursor wetting. Face-to-face wetting with polymeric solutions resulted in partial mixing of both components, leading to tubular nanostructures characterized by a longitudinal composition gradient. Mixing of the components infiltrated from the opposite surfaces could be prevented by face-to-face wetting with polymeric melts, leading to the formation of tubular components predominantly consisting of the pure components that were separated by sharp interfaces.

Gradient nanowires and nanotubes

“…Based on the concept of the WASTE process 17 the concept was extended for the preparation of nanotubes from the solution state and melt state with longitudinal gradients and segmented nanotubes 18 and a combination of longitudinal gradient and cross‐sectional gradient 19 by face‐to‐face wetting. According to the concept of bidirectional wetting nanoporous discs with pores open at both ends were simultaneously exposed to different polymeric solutions.…”

“… (online colour at: http://www.pss-b.com/) SEM of PVC/PSBr gradient nanotubes showing tubular openings (a), different morphologies along tube main axis (b), two‐dimensional mapping of the intensity of the Kα peak of Cl (c) and Br (d) – the color intensity encodes intensities of the elements 18. …”

“…The infiltration of the fluorescent PMMA/9‐vinylanthracen melt occurs at a much higher rate than the infiltration of the second component PMMA with significantly higher molecular weight. All tubes are fluorescent over their entire length 18.…”

“… (online colour at: http://www.pss-b.com/) (a and b) Fluorescent microscopy images of non‐fluorescent PMMA tube segments and fluorescent PMMA/9‐vinylanthracen tube segments obtained by face‐to‐face melt infiltration of PMMA and PMMA/9‐vinylanthracen having similar molecular weights. The red circle in (b) indicates the interface between a non‐luminescent and a luminescent part of the tube 18. …”

Segmented polymer nanowires and nanorods by one-step template wetting with a hyperbranched polymer and linear polymer blend

“…16 Room-temperature face-to-face wetting with polymeric solutions of poly(4-chlorostyrene) (PClS), poly(4-bromostyrene) (PBrS), and poly-(vinylchloride) (PVC) was also introduced to fabricate segmented PVC/PBrS and PClS/PBrS nanotubes with sharp interfaces. 17 Although progresses have been made to extend the range of processable polymers, most of the reported procedures require multi-steps and/or are time-consuming.…”