Jikui Wang

One-step modification of PU sponges for selective absorption of oil–water mixtures

A porous PDMS–PU sponge with excellent wettability was employed in this investigation for the fast absorption of oils and organic solvents. In this study, a robust superhydrophobic sponge was based on a simple dipping–coating method and HCl corrosion. The as-prepared PDMS–PU sponge possesses the advantages of convenient adsorbent collection and good recyclability. By combining the special wettability and high roughness, the sponges exhibited high absorption capacity and selectivity when used as absorptive materials for separate oil–water mixtures. Thus, these sponges show great potential for the large-scale removal of organic contaminants or oil spills from water.

Smart PDMS sponge with switchable pH-responsive wetting surface for oil/water separation

A smart sponge with porous structures and switchable hydrophobic–oleophilic or hydrophilic–underwater–oleophobic properties by varying the medium pH is successfully fabricated. This special sponge with a controllable wetting surface is prepared simply by introducing active hydroxyls on the surface of a fabricated poly(dimethylsiloxane) (PDMS) sponge and then esterifying it with picolinic acid. Under the synergistic action of raw PDMS chains and functionalized chains in different media the water contact angles decrease from 138° (pH = 7.0) to 10° (pH = 2.0), whereas the oil contact angles increase from 0° (pH = 7.0) to 140° (pH = 2.0) from neutral or alkaline to very acidic media underwater. The basic structure, chemical components, element type, contact angle and restorability of the sponge are also investigated. Owing to its stability and great practicability, this functionalized pH-responsive sponge can be directly used for oil/water separation. The switchable oil capture and release in aqueous media by our functionalized sponge can provide a new avenue to avoid secondary pollution in oil/water separation processes.

Preparation of Monomer Casting Nylon-6-b-Polydimethylsiloxane Copolymers with Enhanced Mechanical and Surface Properties

ABSTRACT Nylon-6-b-polydimethylsiloxane copolymer was synthesized with macroinitiator through in situ polymerization. The macroinitiator with two chain-growing centers per molecule is based on hydroxyl terminated polydimethylsiloxane (PDMS) functionalized with diisocyanate. The influence of PDMS contents on the properties of copolymers was studied. Differential scanning calorimetry and X-ray diffraction were used to investigate the melting temperature, crystallization temperature and crystal form of samples, and the results showed that the crystallinity of polymers decreased. The mechanical properties of samples were studied by notched-impact testing and tension test. The notched impact strength was improved by 200% with PDMS concentration up to 4 wt%. The form of scaly was seen by scanning electron microscope proved the improvements of the impact strength of the copolymer. The water contact angles test showed that the surface tension of copolymers decreased with the PDMS content increasing and the surface of copolymer changed from hydrophilic to hydrophobic. GRAPHICAL ABSTRACT

Highly stretchable polymer conductors based on as-prepared PEDOT:PSA/n-PAA hydrogels

Conducting polymers with inherently good flexibility and conductivity are good candidates for stretchable conductor applications, such as wearable electronics and healthcare devices. In this article, the crosslinked PAA (polyacrylic acid, n-PAA) hydrogels were fabricated via the reaction between hydrophilic groups of polymers in the presence of the water-based silicone crosslinking agent. By using the PEDOT:PSA (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate-co-acrylic acid) as a conducting component, the conductive hydrogels prepared by this method are highly conductive with a value of 2.00 S cm−1, highly stretchable with 800% strain and exceedingly stable in ambient air for a long time; also they possess superior properties to similar crosslinking methods. The resistance change with stretching is almost strain-insensitive up to 50% strain after 1000 fatigue cycles.

Significant reinforcement of polypropylene/wood flour composites by high extent of interfacial interaction

Polypropylene (PP)/wood flour/fiber (WF) composites with strong interfacial compatibility were prepared, and properties of the composites were studied. First, the wood fiber was surface modified by alkali treatment—this process is also termed as fibrillation that creates rough surface, cavities, and much interspace between smaller fibrils. Then multi-monomer grafted copolymers of PP (MPP-St) and PP wax (MPPW-St) were synthesized. The so synthesized MPP-St/MPPW-St well compatibilized the interfaces of the PP/alkali-treated WF (TWF) composites. Mechanical property and water resistance results demonstrated that synergistically compatibilized PP/TWF composites had a better performance than composites compatibilized by MPE-St or MPPW-St separately, uncompatibilized composites, and PP/untreated wood flour (UWF) composites. The interfacial structures of all these composites were characterized by scanning electron microscopy. A three-dimensional mold was constructed to reveal that MPP-St affords a strong interfacial interaction between PP and rough surface of treated fiber, while MPPW-St supplements the interfacial interaction by permeating into the interspace between smaller fibrils of alkali-treated fiber. The mold fitted the results very well.