Robust Non-Wetting PTFE Surfaces by Femtosecond  Laser Machining

Fang, Liang; Lehr, Jorge; Danielczak, Lisa; Leask, Richard L.; Kietzig, Anne‐Marie

doi:10.3390/ijms150813681

Cited by 63 publications

(46 citation statements)

References 34 publications

(46 reference statements)

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“…Recently, Liang et al (2014) have demonstrated that homogeneously texturing poly(tetrafluoroethylene) (PTFE) leads to the formation of an air-trapping porous structure that is effectively superhydrophobic [15]. Since then, our recent work has shown that similar structures can form on a wide variety of polymers [16].…”

Section: Introductionmentioning

confidence: 99%

Optical and chemical effects governing femtosecond laser-induced structure formation on polymer surfaces

Assaf¹,

Kietzig²

2018

Materials Today Communications

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With the emergence of femtosecond technology, laser machining has recently led to the creation of novel porous structures on polymers. However, the mechanism behind their formation is yet to be understood. In this study, the dependence of femtosecond laser-induced surface structure on processing parameters is established at two distinct wavelengths (800 nm and 275 nm) for six different polymer films: LDPE, PC, PET, PLA, PMMA, and PTFE. All of the observed structures are then optically and chemically characterized as a first step towards elucidating their formation mechanism. The threshold fluence at operating conditions was determined to be the main parameter affecting porosity formation during machining. Furthermore, for transparent films, a transition from multiphoton to linear absorption is observed to occur at 800 nm but not at 275 nm. This shift in optical properties was determined to be a major contributor to incubation effects.These observations are also in agreement with UV/VIS analysis as measurements show that polymers with a cut-off wavelength lower than that of the laser beam undergo a shift in absorption behavior. Finally, some polymers experience a continuous darkening of their surface with increasing fluence due to an increasing degree of photo-oxidation.

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Section: Introductionmentioning

confidence: 99%

Optical and chemical effects governing femtosecond laser-induced structure formation on polymer surfaces

Assaf¹,

Kietzig²

2018

Materials Today Communications

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“…The understanding of wetting of a surface by a liquid, leading to the spreading of those liquids over the surface, can be seen as a crucial factor that is adopted within surface chemistry and surface engineering including applications such as biomaterials [1][2][3] and coating technologies [4,5]. As demonstrated in current surface engineering literature, wettability characteristics of many materials can be altered by the means of laser-induced surface treatment [1,6,7] and other surface treatments [8][9][10]. Despite increased academic recognition and demand for greater industrial deployment, wetting and the effects of surface modification are still not fully understood within the engineering community.…”

Section: Introductionmentioning

confidence: 99%

Modulating the wettability characteristics and bioactivity of polymeric materials using laser surface treatment

Waugh¹,

Lawrence²,

Shukla³

2016

Journal of Laser Applications

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It has been thoroughly demonstrated previously that lasers hold the ability to modulate surface properties of materials with the result being utilization of such lasers in both research and industry. What is more, these laser surface treatments have been shown to affect the adhesion characteristics and bio-functionality of those materials. This paper details the use of a Synrad CO2 laser marking system to surface treat nylon 6,6 and polytetrafluoroethylene (PTFE). The laser-modified surfaces were analyzed using 3D surface profilometry to ascertain an increase in surface roughness when compared to the as-received samples. The wettability characteristics were determined using the sessile drop method and showed variations in contact angle for both the nylon 6,6 and PTFE. For the PTFE it was shown that the laser surface treatment gave rise to a more hydrophobic surface with contact angles of up to 150° being achieved. For the nylon 6,6, it was observed that the contact angle was modulated approximately ±10° for different samples which could be attributed to a likely mixed state wetting regime. The effects of the laser surface treatment on osteoblast cell and stem cell growth is discussed showing an overall enhancement of biomimetic properties, especially for the nylon 6,6. This work investigates the potential governing parameters which drives the wettability/adhesion characteristics and bioactivity of the laser surface treated polymeric materials.

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“…These laser-induced structures can be used to alter the wettability of a material, resulting in a more hydrophobic or hydrophilic surface [10,11,26]. Other uses of such laser-induced topographies include surface coloration [27,28], surfaceenhanced Raman scattering (SERS) [29], reduced cell growth [30,31], and improved broadband optical absorption [15,32] for applications such as photovoltaics [33]. A comprehensive review of fs-laser surface texturing on metals has been provided by Ahmmed et al [1].…”

Section: Introductionmentioning

confidence: 99%

Investigating and understanding the effects of multiple femtosecond laser scans on the surface topography of stainless steel 304 and titanium

Ling

Saïd

Brodusch

et al. 2015

Applied Surface Science

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The majority of studies performed on the formation of surface features by femtosecond laser radiation focuses on single scan procedures, i.e. solely manipulating the laser beam once over the target area to fabricate different surface topographies. In this work, the effect of scanning stainless steel 304 multiple times with femtosecond laser pulses is thoroughly investigated over a wide range of fluences. The resultant laserinduced surface topographies can be categorized into two different regimes. In the low fluence regime (F Σline,max < 130 J/cm 2 ), ellipsoidal cones (randomly distributed surface protrusions covered by several layers of nanoparticles) are formed. Based on chemical, crystallographic, and topographical analyses, we conclude that these ellipsoidal cones are composed of unablated steel whose conical geometry offers a significant degree of fluence reduction (35-52%). Therefore, the rest of the irradiated area is preferentially ablated at a higher rate than the ellipsoidal cones. The second, or high fluence regime (F Σline,max > 130 J/cm 2 ) consists of laser-induced surface patterns such as columnar and chaotic structures. Here, the surface topography showed little to no change even when the target was scanned repeatedly. This is in stark contrast to the ellipsoidal cones in the first regime, which evolve and grow continuously as more laser passes are applied. Keywords

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Robust Non-Wetting PTFE Surfaces by Femtosecond Laser Machining

Cited by 63 publications

References 34 publications

Optical and chemical effects governing femtosecond laser-induced structure formation on polymer surfaces

Optical and chemical effects governing femtosecond laser-induced structure formation on polymer surfaces

Modulating the wettability characteristics and bioactivity of polymeric materials using laser surface treatment

Investigating and understanding the effects of multiple femtosecond laser scans on the surface topography of stainless steel 304 and titanium

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