Bio-Inspired Fluorine-Free Self-Cleaning Polymer Coatings

Abstract

Bio-inspired fluorine-free and self-cleaning polymer coatings were developed using a combination of self-assembly and UV-printing processes. Nasturtium and lotus leaves were selected as natural template surfaces. A UV-curable acrylate oligomer and three acrylated siloxane comonomers with different molecular weights were used. The spontaneous migration of the comonomers towards the polymer–air interface was found to be faster for comonomers with higher molecular weight, and enabled to create hydrophobic surfaces with a water contact angle (WCA) of 105°. The replication fidelity was limited for the nasturtium surface, due to a lack of replication of the sub-micron features. It was accurate for the lotus leaf surface whose hierarchical texture, comprising micropapillae and sub-micron crystalloids, was well reproduced in the acrylate/comonomer material. The WCA of synthetic replica of lotus increased from 144° to 152° with increasing creep time under pressure to 5 min prior to polymerization. In spite of a water sliding angle above 10°, the synthetic lotus surface was self-cleaning with water droplets when contaminated with hydrophobic pepper particles, provided that the droplets had some kinetic energy.

Photoinduced Processes as a Way to Sustainable Polymers and Innovation in Polymeric Materials

“…Patterning techniques based on photopolymerization can also be used to prepare functional polymer surfaces, which can be applied in the field of coatings. An example is reported in another collaborative work [ 43 ] of our group, where a hierarchical patterned polymer surface was fabricated by light-induced nanoimprinting ( Figure 4 ). The pattern of Figure 4 is a bio-inspired fluorine-free and self-cleaning polymer coating, developed using a combination of self-assembly and low-pressure UV nanoimprint lithography (UVNIL) process.…”

“…The process and the material adopted in the work represent an efficient alternative to most self-cleaning polymers developed: in fact, neither fluorinated compounds nor nanoparticles, which create concerns for their biopersistency and for uncontrolled release issues, respectively, were used. Moreover, the process can be easily scalable to cost-effective, large area surfaces [ 43 ].…”

Perfluoropolyalkylether Maleimides for Protection From Oxygen Inhibition and Surface Modification of Photoinitiator-Free UV-Cured Polymers

“…As previously mentioned, polymers obtained by photopolymerization often come in the form of film and are used as coatings, adhesives, inks where performance depends most importantly on surface properties (i.e., adhesion, wettability, self-cleaning, printability etc.). Tailoring the surface of UV-cured polymers while keeping the bulk properties unchanged is possible by introducing a small amount of a surface-active comonomer in the reactive formulation (Vitale et al, 2018;Wasser et al, 2018). This approach has been widely applied to acrylic, vinyl ether, epoxy systems using fluorinated comonomers (Vitale et al, 2015;Wasser et al, 2018).…”

“…Tailoring the surface of UV-cured polymers while keeping the bulk properties unchanged is possible by introducing a small amount of a surface-active comonomer in the reactive formulation (Vitale et al, 2018;Wasser et al, 2018). This approach has been widely applied to acrylic, vinyl ether, epoxy systems using fluorinated comonomers (Vitale et al, 2015;Wasser et al, 2018). In this work, we describe the influence of fluorinated maleimides for the modification of photoinitiator-free maleimides-based coatings.…”

Preparation of Hierarchically Structured Polystyrene Surfaces with Superhydrophobic Properties by Plasma-Assisted Fluorination

“…Hierarchically structured surfaces with well-defined textures play very significant roles in sophisticated applications in sensors [1], photonics [2], tissue engineering [3], and superhydrophobic materials [4][5][6][7][8][9][10][11][12]. Generally, these surfaces are prepared in several steps combining mechanical, laser machining, physicochemical, and plasma technologies [13][14][15][16].…”