One-step rapid co-deposition of oxidant induced mussel-polyphenol coating on PVDF substrate for separating oily water

Enhancing the strength and toughness of polylactic acid-based composites through one-step co-deposition of active coating onto wood fiber

A facial strategy of co-deposition is proposed to enhance the interfacial bonding in wood fiber (WF)/polylactic acid (PLA) composites. Dopamine or tannic acid (TA) was co-deposited with 3-aminopropyltriethoxysilane (APTES) onto the WF surface to create active coatings. These coatings were formed through Michael addition and Schiff base reactions and effectively attached to the WF through a combination of hydrogen and covalent bonding. Such active coatings facilitated the connection between WF and PLA through both covalent bonds and physical entanglements, thereby enhancing the interfacial interactions and compatibility between the two components. The co-deposition of TA with APTES was found to be more effective than with dopamine, leading to a dramatic improvement in the tensile strength and elongation at break of the composites by 33.4 % and 185.9 %, respectively. This work offers a facile method to prepare high performance plant fiber reinforced PLA composites, thereby broadening the potential applications of PLA.

Rapid Construction of Caffeic Acid/p-Phenylenediamine Antifouling Hydrophilic Coating on a PVDF Membrane for Emulsion Separation

The current methods of constructing modification strategies for hydrophilic membranes are time-consuming, complex in operation, and poor in universality, which limit their application on membranes. In this work, inspired by the adhesion properties and versatility of caffeic acid (CA) and p-phenylenediamine (PPDA), a simple, rapid, and universal method was designed for the separation of oil-in-water emulsion by preparing a stable hydrophilic coating separation membrane. The preparation time of the membrane was shortened to 40 min. The developed PVDF-PCA/PPDA membrane showed superhydrophilic and underwater superoleophobic properties. When applied to petroleum ether-in-water emulsion, isooctane-in-water emulsion, and dodecane-in-water emulsion separation, the oil rejection was more than 99.0%. In the circulating separation of 10 g/L soybean oil-in-water emulsion, the oil rejection was more than 99.3%, and the highest flux was 1036 L·m-2·h-1. The prepared PVDF-PCA/PPDA membrane performed well in the separation test of oily wastewater. The proposed strategy is simple and rapid; it may become a universal method for preparing membranes with super strong antifouling properties against viscous oil and accelerate the research progress of membrane separation of oil-in-water emulsions.

Facile Fabrication of Superwetting PVDF Membrane for Highly Efficient Oil/Water Separation

A novel superhydrophilic and underwater superoleophobic modified PVDF membrane for oil/water separation was fabricated through a modified blending approach. Pluronic F127 and amphiphilic copolymer P (MMA-AA) were directly blended with PVDF as a hydrophilic polymeric additive to prepare membranes via phase inversion induced by immersion precipitation. Then, the as-prepared microfiltration membranes were annealed at 160 °C for a short time and quenched to room temperature. The resultant membranes exhibited contact angles of hexane larger than 150° no matter whether in an acidic or basic environment. For 1, 2-dichloroethane droplets, the membrane surface showed a change from superoleophilic to superoleophobic under water with aqueous solutions with pH values from 2 to 13. This as-prepared membrane has good mechanical strength and can then be applied for oil and water mixture separation.