Effect of silane coupling agents with different non-hydrolytic groups on tensile modulus of composite PDMS crosslinked membranes

Insights into the Mechanical Properties of Ultrathin Perfluoropolyether-Silane Coatings

Ultrathin perfluoropolyether-silane (PFPE-silane) films offer excellent functionality as antifingerprint coatings for display touchscreens due to their oleophobic, hydrophobic, and good adhesion properties. During smartphone use, PFPE-silane coatings undergo many abrasion cycles which limit the coating lifetime, so a better understanding of how to optimize the film structure for improved mechanical durability is desired. However, the hydrophobic and ultrathin (1-10 nm) nature of PFPE-silane films renders them very difficult to experimentally characterize. In this study, the cohesive fracture energy and elastic modulus, which are directly correlated with hardness and better wear resistance of 3.5 nm-thick PFPE-silane films were, respectively, measured by double cantilever beam testing and atomic force microscopy indentation. Both the cohesive fracture energy and modulus are shown to be highly dependent on the underlying film structure. Both values increase with optimal substrate conditions and a higher number of silane groups in the PFPE-silane precursor. The higher cohesive fracture energy and modulus values are suggested to be the result of the changes in the film chemistry and structure, leading to higher cross-linking density. Therefore, future work on optimizing PFPE-silane film wear resistance should focus on pathways to improve the cross-linking density. Subcritical fracture testing in humid environments reveals that humidity negatively affects the fracture properties of PFPE-silane films.

Effect of N-(2-Aminoethyl)-3-Aminopropyltrimethoxysilane on the Adhesion of the Modified Silicone Tie-Coating to Epoxy Primer

In this work, modified silicone tie-paints were prepared in a simple way for securing adhesion between the epoxy anticorrosive primer and silicone fouling release coating. Hydroxy-terminated polydimethylsiloxane (PDMS) mixture containing fillers and accessory ingredient was prepared as base component. N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane (DAMO) was mechanically mixed with other functional additives as curing component. ATR-FTIR, XPS, SEM and tensile tests were used to investigate the chemical structure, morphology and mechanical properties of the tie-coatings. It was focused on the effect of the DAMO content on the adhesion of the tie-coating to epoxy primer. Peel off and shear tests were carried out to evaluate the adhesion. The results showed that introducing DAMO can significantly improve the properties of the tie-coating. The adhesion between the tie-coating and the epoxy primer increases with the increase of DAMO content, but the excessive DAMO content will decrease the fracture strength of the tie-coating and decrease the quality of the coating. When the DAMO content in tie-coating is 1.97 wt.%, the tie-coating performs excellent in the interlaminar adhesion, shear strength and mechanical properties.

Highly Dual Antifouling and Antibacterial Ultrafiltration Membranes Modified with Silane Coupling Agent and Capsaicin-Mimic Moieties

Dual antifouling and antibacterial polysulfone(PSf)/polyethersulfone(PES) hybrid membranes were developed by the synergy of capsaicin-mimic N-(5-methyl acrylamide-2,3,4 hydroxy benzyl) acrylamide (AMTHBA) and vinyl triethylene (b-methoxy ethoxy) silane (VTMES). First, AMTHBA as a natural antimicrobial agent was incorporated into a casting solution via "microwave-assistance (MWA) in situ polymerization-blending" process to construct a hydroxyl-rich environment. Then, VTMES crosslinked to a hydroxyl-rich polymer matrix via hydrolytic condensation, and the influence of VTMES content on the hybrid membrane properties was systematically investigated. When the VTMES added amount was 1.0 wt %, the hybrid membrane achieved an optimal separation performance including a steady-state humic acid (HA) (5 mg/L) permeation flux of 326 L·m-2·h-1 and a rejection percentage of 97%. The antibacterial tests revealed that the hybrid membranes exhibited sustained bactericidal activity and effective inhibition of bacterial adhesion. Besides, the dual-functional membranes were clean as new after two-cycles filtration (with a cleaning efficiency of ~90%), indicating that the network silicone film on the surface benefits the foulant repellence. Hopefully, the dual-functional membranes constructed in this study can be applicable to the pretreatment stage of water treatment.

The effect of organosilicon modifier structure on the efficiency of the polybutadiene hydrosilylation process

Real-time FT-IR spectroscopy permitted us to determine the influence of steoelectronic properties of functional groups on hydrosilylation. This allowed the synthesis of polybutadienes equipped with attractive silicon-based functional groups.

Effect of different silane coupling agents on cryogenic properties of silica-reinforced epoxy composites

Epoxy-based composites containing silica modified by various silane coupling agents (SCAs) were prepared. The effect of the SCAs and the silica content on the thermal, mechanical properties, and fracture toughness of the nanocomposites was investigated. The particle size and dispersion state of the modified silica particles in the matrix were determined by transmission electron microscopy. The modification of silica with SCAs was verified by Fourier transform infrared spectroscopy. The specific tensile properties at ambient temperature (AT, 298 K) were compared with those at cryogenic (LT, 77 K) condition for silica content of 1−5 wt%. The effect of certain types of coupling agents on the thermal properties of the composites was also investigated. The Tg of all amino-silane-modified composites tended to be improved at low silica contents, while that of epoxy-silane-modified composites seemed to be enhanced further at high silica content. The tensile properties of the nanocomposites both at AT and LT tended to be enhanced at lower silica content, especially the failure strain. The fracture toughness ( KIC) turned out to be better enhanced by coupling agents at LT. The difference of the toughening mechanism at AT and LT was examined according to the morphology of the fracture surfaces using the scanning electron microscopy.