Zhichao Xu

Superhydrophobic nanocomposite coatings with photoinitiated three-dimensional networks based on reactive graphene nanosheet-induced self-wrinkling patterned surfaces

HYPOTHESISnBionic superhydrophobicity including high contact angle, low sliding angle and nonstick property, combined with both strong pH and ultraviolet (UV) resistance, is difficult to simultaneously achieve for large-scale preparation of superhydrophobic surfaces by blending polymer with a nonreactive inorganic nanofiller.nnnEXPERIMENTSnA series of high pH and UV-irradiation-resistant superhydrophobic nanocomposite films were prepared through UV-light-assisted chemical cross-linking among ternary components under nitrogen protection. Ethoxylated bisphenol A diacrylate, 2-(perfluorooctyl) ethyl acrylate, reactive thiol-coupled graphene nanosheets and photoinitiator were evenly mixed, followed by UV-irradiation curing.nnnFINDINGSnAbundant 3D networks could be formed. A robust self-wrinkling surface morphology was formed due to a UV-curing-induced inner tension in the composites, 2D morphology-induced flexibility for graphene nanosheets and fluorine-bearing component-induced phase separation at the wetted surfaces. High roughness and use of the fluorine element endows the surfaces with superhydrophobicity and oleophobicity. A favorable nonstick performance was obtained. Superhydrophobicity could be maintained despite changing the film-forming substrate, pH of soaking solutions from 1 to 12, or use of a prolonged UV-irradiation time reaching 120u202fh. Therefore, both superhydrophobicity/oleophobicity and strong pH/UV resistance are finely balanced. This work might open up the way for large-scale fabrication of promising superhydrophobic surfaces.

Robust wear and pH endurance achieved on snake-shaped silica hybrid nanowire self-woven superamphiphobic membranes with layer-stacked porous 3D networks

Bio-inspired superamphiphobicity, including high contact angles, low sliding angles and non-stick traits, in combination with high durability, such as strong wear resistance, pH endurance and mechanical properties, are difficult to simultaneously obtain in the large-scale fabrication of amphiphobic materials with the presently used blends of polymers and surface-modified hard inorganic nanoparticles. In the current work, a series of highly abrasion-resistant superamphiphobic membranes applicable in a wide pH range were fabricated by a facile vacuum filtration process from suspensions containing snake-shaped silica hybrid nanowires. Tetraethyl orthosilicate, trimethoxyoctadecylsilane and 2-perfluorooctylethyltrimethoxysilane monomers were hydrolyzed and condensed to yield silica nanowires through finely regulated anisotropic sol–gel growth in a water/oil emulsion. The snake-shaped morphology, aspect ratio and elemental distribution of the nanowires were tailored to endow them with strong self-assembly capacity due to capillary force action. As a result, a porous 3D network morphology and hierarchical structure were achieved across the entire membrane thickness based on the self-weaving behavior of the nanowires. Superamphiphobicity was acquired, including a maximum water contact angle (WCA) of ca. 162° and an oil contact angle (OCA) of ca. 155°. The water sliding angle (WSA) and oil sliding angle (OSA) were less than 5°. Desirable non-stick, anti-fouling, flexible and self-standing traits were obtained. Well-maintained superamphiphobicity was observed in a wide pH range (1 to 12). After 300 abrasion cycles, the superamphiphobicity was retained due to the porous 3D network morphology and hierarchical structure across the whole membrane thickness. Therefore, excellent superamphiphobicity and damage tolerance were finely balanced on the surfaces of these nanowire membranes. This work may enable large-scale preparation of promising superamphiphobic surfaces.

Study on affecting factors of curing rate in ultraviolet curing adhesives containing modified acrylic ester prepolymers

Ultraviolet (UV) curing adhesives have been extensively utilized in fields of health care and electronic components due to low energy consumption and solvent pollution. The most used system is modi...

Highly Retained Electric and Mechanical Traits in Micron-Sized Glass Fibers Filled Epoxy Composite Based on Heat-Oxygen Ageing

The epoxy based composite materials with a high ageing resistance property have attracted a wide attention in the field of high-electric-insulation electronic packaging. However, both of the highly retained electrical and mechanical performances are difficult to simultaneously achieve in composite materials once a longer heat-oxygen ageing at a high temperature is applied onto the materials. In order to realize the ageing-resistant high mechanical, electric breakdown and dielectric properties simultaneously in composite, in this work, an epoxy based composite filled with the high-insulation micron-sized glass fiber filler has been prepared, and its shock resistance strength, electric breakdown strength, dielectric constant, dielectric loss and conductivity after a severe heat-oxygen ageing have been investigated in detail, compared with that before the ageing. Although the ageing was operated at 150xa0°C for 25xa0days, the electric and mechanical properties of the composite were still finely retained, including 60% retention for shock resistance strength, 70% for breakdown strength, 80% for dielectric constant, dielectric loss below 0.1 and conductivity below 2u2009×u200910−9xa0Sxa0cm−1. The epoxy matrix and glass fiber filler were responsible for the small decline and high retention for the properties in composite, respectively. This work might open the way for the large-scale preparation of the promising epoxy based composites with the highly retained ageing-resistant electric and mechanical properties based on incorporating the high-insulation fiber fillers.

Study on gel weight fraction of ultraviolet-cured acrylic adhesives

Ultraviolet (UV)-cured adhesives have attracted plenty of attention in the fields of health care and electronic components thanks to low energy loss and environment pollution. UV-cured adhesives bearing epoxy acrylate prepolymers have been extensively utilized, ascribed to low cost and high stability. However, the gel content of UV-cured adhesives has hardly been investigated in detail. The gel content has been found to strongly affect the mechanical properties and serving life of adhesives. We have found the strong composition dependence of adhesive performances of UV-cured adhesives before. To clarify the influencing factors of gel content in UV-cured adhesives containing epoxy acrylate prepolymers, in this work, a family of UV-cured adhesives with epoxy acrylate constituents have been elaborately designed and further fabricated. The influences of prepolymer kind, UV photoinitiator kind, UV photoinitiator concentration, reactive diluent concentration, feed style during preparing prepolymers and film thickness on gel weight fraction of cured adhesive films were deeply researched. This work might open the door to the large-scale preparation of promising high-performance UV-cured adhesives with a higher gel weight fraction based on regulating the formula.Graphical Abstract