In situ poly(melamine-formaldehyde) microencapsulation of diglycidyl ether of bisphenol-A epoxy and pentaerythritol tetrakis(3-mercaptopropionate) for self-healing applications

In this study, microcapsules as potential candidates for self-healing agents were prepared by in situ polymerisation, taking place in oil-in-water emulsion. Poly(melamine-formaldehyde) is employed as shell material and diglycidyl ether of bisphenol A as polymerisable core materials and Pentaerythritol Tetrakis(3-Mercaptopropionate) as its hardener. The geometry, shell features, size distributions, core content, and the reactivity of the microcapsules were studied by scanning electron microscopy (SEM), optical microscopy (OM), Soxhlet extraction method and differential scanning calorimetry (DSC). Microcapsules with different sizes and distributions were obtained by adjusting the stirring speeds during the preparation stage. From the results, it was established that the spherical microcapsules fabricated using this technique, resulted in satisfactory size and shell structure with shell thickness of less than 2 μm. The microcapsules possess high core content at about 90 wt.% for each size range of microcapsules and it was also observed that the viscosity of the core content decreased at an elevated temperature. The results obtained in this work indicate that these microcapsules possess the characteristics that can be potentially used for self-healing applications.

Modulating the surface and mechanical properties of textile by oil-in-water emulsion design

The synergistic effect of oil viscosity and oil droplet size on the deposition profile of oil on cotton fabric was studied using polydimethylsiloxane (PDMS) as a model oil-in-water emulsion system.

Performance of Strobilanthes crispus Leaves Extract as Potential Antioxidant Compound in Oil-in-water Emulsion

Excess of free radicals accelerates the degradation of oil-in-water (O/W) emulsion due to oxidative damage resulting in low emulsion quality such as in lotion formulation. The blend of antioxidants in O/W emulsion could reduce the damage caused by the radical compounds. The crude extract of Strobilanthes crispus (S. crispus) leaves was screened for assessing bioactive phytochemical constituents. By using various chemical assays, the extract of S. crispus leaves revealed the presence of tannins, steroids, flavonoids, terpenoids and glycosides. Besides that, the antioxidant activity of the leaf extract, spray-dried extract, a lotion containing extract and other local and abroad commercial lotions were determined as references using standard methods such as total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and reducing power assay. In terms of TFC, the highest, 10.591±0.01 mg QE/g was recorded in crude extract along with the highest reducing power and percentage inhibition, 25.40±0.02 mg GAE/g and 88.89 % respectively. The result from TPC value can be a good indicator for a longer shelf life of the O/W emulsion if compared to other results from TPF, reducing power and DPPH value. From this study, it can be concluded that S. crispus has potential as a good natural antioxidant ingredient for the emulsion of O/W formulation.

Mussel-Inspired Fabrication of PDA@PAN Electrospun Nanofibrous Membrane for Oil-in-Water Emulsion Separation

Emulsified oily wastewater threatens human health seriously, and traditional technologies are unable to separate emulsion containing small sized oil droplets. Currently, oil–water emulsions are usually separated by special wettability membranes, and researchers are devoted to developing membranes with excellent antifouling performance and high permeability. Herein, a novel, simple and low-cost method has been proposed for the separation of emulsion containing surfactants. Polyacrylonitrile (PAN) nanofibers were prepared via electrospinning and then coated by polydopamine (PDA) by using self-polymerization reactions in aqueous solutions. The morphology, structure and oil-in-water emulsion separation properties of the as-prepared PDA@PAN nanofibrous membrane were tested. The results show that PDA@PAN nanofibrous membrane has superhydrophilicity and almost no adhesion to crude oil in water, which exhibits excellent oil–water separation ability. The permeability and separation efficiency of n-hexane/water emulsion are up to 1570 Lm−2 h−1 bar−1 and 96.1%, respectively. Furthermore, after 10 cycles of separation, the permeability and separation efficiency values do not decrease significantly, indicating its good recycling performance. This research develops a new method for preparing oil–water separation membrane, which can be used for efficient oil-in-water emulsion separation.