We have prepared a series of novel gemini surfactants having ester bonds in their structures. These surfactants possess two identical hydrophilic polyethylene glycol moieties, two hydrophobic alkyl group moieties, and an anionic spacer. The structures of these compounds were confirmed through infrared and nuclear magnetic resonance spectroscopic and elemental analyses. The novel gemini surfactants exhibit excellent surface activity in terms of their surface tension, low-foaming, wetting power, and fluorescence properties. The presence of the ester linkages made these structures cleavable surfactants.
The complex process of wound healing depends on the coordinated interaction between various immunological and biological systems, which can be aided by technology. This present review provides a broad overview of the medical applications of piezoelectric and triboelectric nanogenerators, focusing on their role in the development of wound healing technology. Based on the finding that the damaged epithelial layer of the wound generates an endogenous bioelectric field to regulate the wound healing process, development of technological device for providing an exogenous electric field has therefore been paid attention. Authors of this review focus on the design and application of piezoelectric and triboelectric materials to manufacture self-powered nanogenerators, and conclude with an outlook on the current challenges and future potential in meeting medical needs and commercialization.
A family of phosphated alkyl oligoglucoside surfactants was prepared by reacting alkyl oligoglucosides with phosphorus oxychloride. The alkyl oligoglucosides were obtained by an usual method in which the glucose is reacted with a fatty alcohol containing 10-18 carbon atoms. These novel phosphated surfactants have been found to exhibit good surface tension, foaming and wetting power. The critical micelle concentration was found to increase with the length of hydrocarbon chain of the surfactant. The surface excess concentration and the interfacial area per surfactant molecule are reported. These phosphated surfactants also exhibit a good performance to improve the whiteness and wetting of cotton fabrics in a hydrogen oxide bleaching system, and they are also found to be more biodegradable than conventional surfactants.
This study synthesized the water-permeable and hydrophobic property of water-based polyurethane (WPU) and applied it to nylon fiber-based functional textiles. Specifically, poly-stearyl acrylate (PSA) homopolymers with different molecular weights were used as end-capping agents in the WPU to form water-based polyurethane with acrylate terminal (WPUA). In the WPUA process, dimethylacetamide was adopted as a neutralizing agent to form a stable WPUA emulsion. The effects of the design parameters, such as the hydrophilic ionic group dimethylol propionic acid (DMPA), the PSA molecular weight and content, were set as the control factors and are analyzed by the Taguchi method and gray relational analysis (GRA). The water-repellent characteristic, water vapor permeability (WVP) and fabric flexural rigidity were considered as performance parameters as multi-qualities. The Taguchi method was based on the analysis of variance and implemented orthogonal arrays for experimental design. Each performance parameter was optimized independently. Then, the performance parameters were optimized together with GRA. According to the experimental results, the most important factor for the water-repellent characteristic, WVP and fabric flexural rigidity is the DMPA content, followed by the PSA molecular weight and content. The corresponding results showed that in the optimal parameter combination, the content of DMPA was 30.8 phm (parts per hundred monomer by weight), the PSA molecular weight was 3000 g/mol and the PSA content was 4 phm. After WPUA padding, the water contact angle of the water-repellent nylon was 135.3°, the WVP was 2271.7 g/m2/day and the flexural rigidity was 2.7 cm.
This study developed a nano-size filler as a thermally conductive filler for a silicone thermal pad (STP) by exfoliating hexagonal-boron nitride ( h-BN) with the chemical exfoliation-free radical polymerization method to produce boron nitride nanosheets (BNNSs). We used N,N-dimethylacrylamide as the intercalation agent. After polymerization, it became poly( N,N-dimethylacrylamide) to exfoliate the h-BN layer. BNNSs were taken as a single-filler and hybrid-fillers with Al2O3 and then compared with h-BN to investigate their effect on the silicone composite properties. As the free radical polymerization reaction time increased, the interlayer distance of BNNSs lengthened to 0.35 nm, while the thickness of h-BN sheets decreased. The X-ray diffractometer results showed how the h-BN (002) crystal plane was enhanced and displaced. The Fourier transform infrared spectra showed that the characteristic peaks of 1372 and 812 cm−1 were enhanced, and the Raman results showed that the E2 g displacement and full width at half maximum increased, thus validating the successful preparation of BNNSs. Based on the scanning electron microscope-transmission electron microscope results, BNNSs with 24-hour reaction time offered the best results with a thickness of 5 nm. The highest thermal conductivity reached 3.66 W m−1 K−1 with the addition of 50 wt% BNNSs, and tensile strength of up to 11.30 kg/cm2. Hybrid-fillers showed enhancement of thermal conductivity to 5.28 W m−1 K−1 and tensile strength to 7.32 kg cm−2. Finally, the STP showed that the volume resistance (>1010 Ω cm), withstand voltage (>10 kV mm−1), and flame resistance (V-0) of the STP prepared by this study comply with the industrial application specifications.
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