Networks from α,ω-Dihydroxypoly(dimethylsiloxane) and (Tridecafluoro-1,1,2,2-tetrahydrooctyl)triethoxysilane:  Surface Microstructures and Surface Characterization

Abstract

The dibutyltin diacetate-catalyzed reaction of (tridecafluoro-1,1,2,2-tetrahydrooctyl)triethoxysilane (FTEOS) with dihydroxy-terminated poly(dimethylsiloxane), HO(Me2SiO) n H, has been used to prepare surface-modified siloxane networks. Surface characterization of these elastomers was carried out with electron spectroscopy for chemical analysis (ESCA) and optical and atomic force microscopy (AFM). Surface phase separation occurs as a function of FTEOS concentration. For example, FTEOS-6x compositions (where 6x is the initial SiOEt/SiOH ratio) exhibited micron scale “islands” of fluorinated siliceous phase (FSP) surrounded by a siloxane-rich “sea”. In FTEOS-12x, the FSP formed a continuous layer on the elastomeric network. Differing dynamic contact angle (DCA) analysis protocols with water as the interrogating fluid showed that water contamination affects force vs distance curve (fdc) data on samples up to FTEOS-10x. Intrinsic wetting behavior is reproduced only with a protocol where clean water is used for each DCA cycle. For FTEOS-12x, an FSP monodomain exists characterized by high θadv (135−6°) and low θrec (55−56°), similar to previously reported values for fluoroalkyl side chain polymers. Long-term testing showed that the coatings undergo slow chemical degradation by water, with the rate depending on composition. FTEOS-12x is chemically stable in water due to the continuous FSP overlayer.

Non-toxic, non-biocide-release antifouling coatings based on molecular structure design for marine applications

“…The copolymers were able to saturate the surface of PDMS blends even at very low loading (0.3 wt%) and showed a peculiar surface composition with two distinct species: (i) hydrocarbon (-CH 3 ) terminals of siloxane chains and (ii) and fluorinated side chains. 86,87 In comparison, the smooth reference PDMS films cured by the typical tetraethylorthosilicate (TEOS) cross-linker showed an increased roughness with cracks and erosion pits on the surface after immersion in water. 84 This combination resulted in blended-films with extremely good AF properties with a higher performance for the detachment of Ulva sporelings and barnacles than pure PDMS, and reduced settlement of cyprid barnacles.…”

Do blood phobia patients hyperventilate during exposure by breathing faster, deeper, or both?

“…Fluoropolymers1–14 have been the focus of extensive research in the development of minimally adhesive surfaces because of their low surface energy, low wettability, and chemical stability, which have also led to studies of their utility as potential antifouling materials for marine applications,15–20 among other things 21–24. It has been established that fouling by marine organisms upon surfaces such as ship hulls involves a process by which the organism secretes an adhesive protein or glycoprotein, either of a hydrophobic25 or hydrophilic nature,26, 27 depending on the fouling species, that provides for binding to the surface through various modes of interaction, including chemical bonding, electrostatic interaction, diffusion, and mechanical interlocking 28.…”

Superhydrophobic Fluorinated Polyurethane Films

“…Table 1 also indicates that a large water CA hysteresis (CAH) is present for the partially fluorinated films. It is well known that contact angle hysteresis arises from three sources [29]: surface roughness, surface chemical heterogeneity and surface reorganization. To find out what caused the high water CAH on these films, the topography of the films was examined by AFM; typical height and phase AFM images are shown in Fig.…”