Jindan Wu

Self-cleaning pH/thermo-responsive cotton fabric with smart-control and reusable functions for oil/water separation

Nowadays, the environmental problem caused by oily wastewater discharge and crude oil leakage has attracted worldwide attention. Recently developed technologies for oil/water separation have been based mainly on materials with special wettability. In this work, a self-cleaning system with smart-control and reusable functions for oil/water separation has been built on cotton fabric via surface-initiated atom transfer radical polymerization (ATRP) of 2-dimethylaminoethyl methacrylate (DMAEMA). The fabric showed high pH- and thermo-responsibility, which was strongly dependent on the pDMAEMA grafting ratio. And by modulating pH or temperature, the fabric switched from superhydrophilic (WCA ∼ 0°) to highly hydrophobic (WCA ∼ 130°), and therefore, were suitable both for the separation of water-rich or oil-rich oil/water mixtures as a type of adsorbent material. The fabric could adsorb oil over 4 times its own weight, and reversibly release it in acidic water, making the fabric easily recyclable.

Thermo-responsive poly(N-isopropylacrylamide) grafted polyester textiles with switchable surface wettability:

Thermo-responsive textile is newly developed and has wide application potentials in various fields. As the most commonly used textile, polyester has advantages in easy care, great durability and low cost. Since it has no reactive groups in fiber for surface functionalization, amino groups were generated by aminolysis in this study. By applying alkali deweighting during the aminolysis process, more -NH2 was produced. Poly(N-isopropylacrylamide) (PNIPAAm) was then grafted onto the surface via surface-initiated atom transfer radical polymerization. Infrared and X-ray photoelectron scanning measurements confirmed the success of PNIPAAm grafting. The thermo-switchable surface wettability was then explored by the test of surface wettability and fiber swelling–deswelling behavior. When the temperature rose, the surface switched from hydrophilic to hydrophobic as the contact angle transited from 0° to 120° reversely. This work established a feasible way and provided a new insight for preparing thermo-responsive polyester fabrics with smart cleaning and smart comfort properties.

Acidity triggered charge-reversible multilayer for the construction of adaptive surfaces with switchable bactericidal and bacterial repelling functions

The acidity of a microenvironment in infected sites was utilized as the trigger to manipulate the bacterial behavior on the surface. Multilayers composed of dopamine-anchored poly(acrylic acid) (PAA-dopa) and chitosan quaternary ammonium salt (Q-CS) were deposited onto a surface via the layer-by-layer (LBL) assembly technology. The multilayer was crosslinked through the reaction of catechol moieties. The surface charge of the multilayer reversibly shifted from positive to negative as the pH increased without influencing the chemical composition and wettability of the top layer. The precise manipulation of the surface charge, and therefore, the biological function was achieved by varying the acidity. The bactericidal efficiency increased 15 times for E. coli, while almost 90% dead S. aureus and 100% E. coli were released from the surface when the pH increased from 5.0 to 7.4. Therefore, the functional surface was regenerated, which is particularly essential during the long-term treatment of chronic wounds. This study presented a new adaptive material responding to microenvironment acidity of the infected sites for efficient and safe antibacterial therapies.

Study of Different Hueing Dyes Deposition on Fabrics during Home Laundry

Abstract The objective of this research was to study the deposition mechanism of hueing dyes on different fabric surfaces. In this study, two types of fabrics and four types of hueing dyes were used to study the dye accumulation behaviors on fabric samples. The results showed that nylon and cotton treated with hueing dyes had a lower b* value and a higher CIE whiteness. Furthermore, the accumulation level of hueing dyes on nylon was much higher than on cotton fabric. The chemical composition of fabrics and molecular structures of hueing dyes were also investigated to study the interactions between different fibers and dyes. The results showed that the over-deposition of hueing dyes on fabric was mainly driven by the electrostatic forces, which could be weakened by adding salts to neutralize the fabric surface charge during home laundry.