Recently, an increasing trend has been noticed towards synthesizing superhydrophobic surface with a water contact angle (WCA) higher than 150° due to its many potential applications including water repellency, oil spill recovery, self-cleaning, antifouling, anti-icing-deicing and so on. Unfortunately, most of the cases the superhydrophobic surface was achieved utilizing either fluorinated materials or organic-inorganic nanoparticles as the water–solid contact angle varies with the surface chemistry and roughness of the solid surface. Herein, we presented a novel approach for preparation of superhydrophobic coating without involving any such hazardous chemicals with the oath to create sustainable world. The superhydrophobic coating was prepared using cellulose nanofibers (CNFs) via a new one step surface modification process. The as-synthesized cellulose surface shows water contact angle (WCA) value of 161°(±2°). When used this material to coat other substrates such as tissue paper, sponge and fabrics, etc., to test the water repellent capacity, the WCA values were found to be between 136-150°(±3°) for the above surfaces. Moreover, the excellent durability of the coating made it very promising for efficient oil/water separation process to self-cleaning textile.
The fabrication of cellulose long-fiber (CL) is necessary for eco-friendly and high strength composites development. CL can be made with cellulose nanofiber (CNF) that has high mechanical strength and modulus. However, the mechanical properties of CL in early studies were shown to be lower than those of original CNF. An idea of fabricating strong CL is to align CNFs so as to make strong hydrogen bond between CNFs. To achieve this, alignment of CNF is very important. In this study, high dc magnetic field is introduced to align the CNFs. The CNFs are aligned perpendicular to the direction of dc magnetic field due to its negative diamagnetic anisotropy. CNFs isolated by TEMPO oxidation and aqueous counter collision method are used in this experiment. The CNF emulsion is located in the high dc magnetic field and cured. Alignment of CNF is investigated by using optical microscopy, scanning electron microscopy and mechanical tensile test.
This paper reports an eco-friendly nanocomposite made with bamboo cellulose nanofiber and chitin micronanofibers. Bamboo has antibacterial property and is beneficial for human living environment meanwhile chitin is safe for food packaging, highly toxic resistant and able to absorb heavy metals. Chitin was micro-nano fibrillated (CT-MNF) by using aqueous counter collision (ACC) physical method. Cellulose nanofiber (CNF) was isolated from bamboo by treating it with 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO)-oxidation followed by ACC method. Bamboo cellulose nanofiber (BA-CNF) was blended with CT-MNF to form BA-CNF nanocomposite. The morphology of BA-CNF and CT-MNF was determined by an atomic force microscopy and field emission scanning electron microscopy. CT-BA nanocomposites were made with different ratios of BA-CNF and CT-MNF. Properties of CT-BA nanocomposites were investigated by using thermogravimetric analysis, UV-visible spectra, and tensile test. The UV-Vis visible spectrum shows better transmittance of the CT-BA nanocomposite with high BA-CNF content. CT-BA nanocomposite has better surface smoothness. By blending BA-CNF with CT-MNF, CT-BA nanocomposite shows improved mechanical properties.
Cellulose nanofiber (CNF) isolation from different resources influences the characteristics of the CNF. There are two methods to isolate CNFs, chemical and physical methods. This paper deals with a 2,2,6,6-tetramethylpiperidine- 1-oxylradical (TEMPO-oxidation) chemical method and aqueous counter collision physical method to isolate CNFs. TEMPO-oxidized cellulose nanofiber was isolated using an aqueous counter collision method from two cellulose resource including Softwood bleached kraft pulp (SW) and Hardwood bleached kraft pulp (HW) resources. The CNFs properties were studied by atomic force microscopy, cross-polarize light and UV visible spectrometer. The width of the isolated CNFs is in the range of 15 nm to 20 nm and the length of cellulose nanofibers is around 1000 nm. The HW-CNF offers better transmittance than the SW-CNF. High transmittance of CNF films from both SWCNF and HW-CNF was observed. In addition, the birefringence of CNFs was observed under cross polarized light. The SW-CNF and HW-CNF films showed birefringence phenomenon. More clear iridescence color of HW-CNF sample than that of SW-CNF case.