Ordered arrays of polymeric nanopores by using inverse nanostructured PTFE surfaces

Abstract

Abstract. We present a simple, efficient, and high-throughput methodology for the fabrication of ordered nanoporouses polymeric surfaces with areas in the range of cm 2 . The procedure is based on a two-stage replication of a master nanostructured pattern. The process starts with the preparation of an ordered array of PTFE (poly(tetrafluorethylene)), PTFE) free-standing nanopillars by wetting self-ordered porous Anodic Aluminum Oxide (AAO) templates with molten PTFE. The nanopillars are 120 nm in diameter and approximately 350 nm in length, while the array extends over cm 2 . The PTFE nanostructuration process induces a surface hydrocarbonation of the nanopillars, as revealed by confocal Raman microscopy/spectroscopy, which enhances the wettability of the originally hydrophobic material and facilitates its subsequent use as an inverse pattern. Thus, the PTFE nanostructure is then used as a negative master for the fabrication of macroscopic hexagonal arrays of nanopores composed of biocompatible poly(vinylalcohol) (PVA). In this particular case, the nanopores are 130-140 nm in diameter and the interpore distance is around 430 nm. Features of such characteristic dimensions are known to be well recognizable by the living cells. Moreover, the inverse mold is not destroyed in the pore array demoulding process and can be reused again for a new pore array fabrication. Therefore, the developed method allows the high throughput production of cm 2 -scale biocompatible nanopores surfaces that could be interesting as two-dimensional scaffolds for tissue repairing or wound healing. Moreover, our approach can be extrapolated to almost any polymer and biopolymer ordered pore array fabrication.

Microphase separation of poly(tert-butyl methacrylate)-block-polystyrene diblock copolymers to form perforated lamellae

“…Block copolymers consisting of incompatible polymer segments linked by covalent bonding may undergo microphase separation in the bulk to form a variety of novel materials with ordered periodic nanostructures [1][2][3]. This property endows microphase-separated block copolymer materials with a great potential application for developing advanced materials and technology in application like lithography, catalysis and filtration [4][5][6][7]. It is well-known that bulk microphase separation behaviors of block copolymers are affected mainly by polymerization degree (N), composition (f), and Flory-Huggins interaction parameter (χ), etc.…”

Robust Fabrication of Polymeric Nanowire with Anodic Aluminum Oxide Templates

“…Once an AAO template is made, nanowires can be fabricated by filling nano-pores with desired material such as metal [41][42][43][44][45][46][47], metal oxide [44,[48][49][50][51][52][53] and polymeric materials [2][3][4][5][6][7][8][9][11][12][13]. To deposit Sample topological features include: (a) thin wall nano-pores with large aspect ratio (e.g., pore depth: diameter >100:1), which is anodized at 1 • C and 60 V for 4 h. (b) thick wall pores with a small pore diameter (e.g.,~50 nm), which is anodized at −3 • C and 140 V for 2 mins.…”

“…To effectively replicate polymeric nanowires within AAO templates, the polymers must first infiltrate nano-pores completely. By exploring precursor films of low surface energy liquids in wetting high surface energy solids, several groups have successfully fabricated nanotubes and nanowires with polymer melts and solutions [4,23,[26][27][28][29][30]. Although these wetting based techniques are highly successfully, the infiltration processes (e.g., infiltration time, depth and wire geometry) rely on maintaining the local disparity between the lower surface energy of polymer liquids and the higher surface energy of AAO templates (i.e., precursor wetting film is a microscopic mechanism) [10], which inevitably results in highly inhomogeneous nanowires over a large AAO template since variations in polymer liquids and nanopores in templates are unavoidable.…”

“…In literature, several groups have successfully used anodized aluminum oxide (AAO) that under proper anodizing conditions contains very well structured nanopores as templates to fabricate nanoscale roughness [2][3][4][5][6][7][8][9]. With advances in polymer sciences and discovery of precursor wetting films [10], nanotubes and nanofibers have been successfully fabricated with several polymers [2][3][4][5][6][7][8][9][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] using methods often termed as "template synthesis" [31,32]. Detailed reviews can be found in [4,26,[28][29][30].…”

“…With advances in polymer sciences and discovery of precursor wetting films [10], nanotubes and nanofibers have been successfully fabricated with several polymers [2][3][4][5][6][7][8][9][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] using methods often termed as "template synthesis" [31,32]. Detailed reviews can be found in [4,26,[28][29][30]. Due to the methods being highly dependent on wetting properties of polymers and templates, they have often been applied to acrylate polymers such as poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF), polyethylene oxide (PEO), polystyrene (PS), and polytetrafluoroethylene (PTFE), summarize key formation mechanisms of these nanopores in the AAO before discussing our protocol used in this work to fabricate AAO templates over a large area (e.g.…”