ABSTRACT
This work presents the first fabrication of smart nonwoven fabric (DSR-CZPP) with extraordinary reversible double-stimulus responsive wettability, where carboxyl groups of cellulose nanocrystals/zinc oxide (CNC/ZnO) nanohybrids deposited on fabric surface can bond with hydroxyl group of the PDMAEMA-b-PHEMA-b-PMAAAB triblock polymer brushes that was prepared by using methyl methacrylate (HEMA), dimethylaminoethyl methacrylate (DMAEMA) and methacrylamide-azobenzene monomer (MAAAB) via reversible addition-fragmentation chain transfer (RAFT). The peculiar reversible double-stimulus responsive wettability of the DSR-CZPP can be modulated by triggering hydrophilic/hydrophobic transitions and lipophilic/oleophobic transitions under dual-stimulations of pH and UV light irradiation. The special molecular structure of the triblock polymer brushes enabled DSR-CZPP to intelligent modulation of oil-water separation under the control of "UV & pH double switch", meanwhile CNC/ZnO simultaneously can induce the photocatalytic degradation of organic dyes. Moreover, DSR-CZPP can have high removal ratios of various pollutants, such as metal ion (Cu2+) and toxic organic solvent (silicone oil, acetone and chloroform). This smart and multifunctional fabric shows great potentials for treating complicated polluted water from most industrial fields.
ABSTRACT
Charged nanocellulose (NC) with a high aspect ratio (larger than 100) extracted from animal or bacterial cellulose and chemical cross-linked NC aerogels have great promising applicability in material science, but facile fabrication of such NC aerogels from plant cellulose by physical cross-linking still remains a major challenge. In this work, carboxylated cellulose nanofiber (CNF) with the highest aspect ratio of 144 was extracted from wasted ginger fibers by a simple one-step acid hydrolysis. Our approach could easily make the carboxylated CNF assemble into robust bulk aerogels with tunable densities and desirable shapes on a large scale (3D macropores to mesopores) by hydrogen bonds. Excitingly, these CNF aerogels had better compression mechanical properties (99.5 kPa at 80% strain) and high shape recovery. Moreover, the CNF aerogels had strong coagulation-flocculation ability (87.1%), removal efficiency of MB dye uptake (127.73 mg/g), and moderate Cu2+ absorption capacity (45.053 mg/g), which were due to assistance mechanisms of charge neutralization, network capture effect, and chain bridging of high aspect ratio carboxylated CNF. This provided a novel physical cross-linking method to design robust aerogels with modulated networked structures to be a general substrate material for industrial applications such as superabsorbent, flocculation, oil-water separation, and potential electrical energy storage materials.
ABSTRACT
Cross-linked polyvinyl alcohol (PVA) composite films with high structural stability were prepared by free radical copolymerization between cellulose nanocrystal (CNC) and maleic anhydride (MAH) modified PVA through spraying Fenton free radical as initiator. The influence of chemical cross-linked and physical network structure on mechanical, thermal and water absorption properties of the composite films were investigated. Compared to PVA and PVA/CNC composite film, significant improvements in the mechanical, thermal and water uptake properties of the cross-linked composite film were found. The tensile strength of the cross-linked composite film was enhanced from 23.1MPa (neat PVA film) and 32.6MPa (PVA/CNC-10%) to 42.5MPa, and the maximum thermal degradation temperature was increased from 266.8°C and 281.2°C to 366.7°C (cross-linked composite film). Besides, the water absorption was reduced from 385.9% and 220.6% to 175.7% for cross-linked composite film. It indicates that compared with physical network structure in PVA/CNC composite film, the multiple cross-linked networks showed excellent thermal stability, resistance of water swelling and structural stability at the same CNC loading level. Thus, the PVA/CNC composite film with the multiple cross-linked network shows greater property reinforcements.
Subject(s)
Cellulose/chemistry , Hydrogen Peroxide/chemistry , Iron/chemistry , Nanoparticles/chemistry , Polyvinyl Alcohol/chemistry , Absorption, Physicochemical , Hydrophobic and Hydrophilic Interactions , Nanocomposites/chemistry , Surface Properties , Temperature , Tensile Strength , Water/chemistryABSTRACT
Professor WU Zhongchao thinks that the occiput-nape region is the important pivot between the head and the trunk and is the extension of the function zone of the back-shu points. This zone is named as the occiput-nape function zone. The position includes the occipital area from Baihui (GV 20) to the margo inferior of occipital bone and the muchal region between the margo inferiors of the spinous process C1 to C7. In the paper, the occiput-nape function zone is verified in terms of the distribution characteristics of meridians and acupoints at the occiput-nape region, the anatomic feature, modern research and clinical application so that a new approach to clinical practice is provided.
