Qingqing Fan

Facile in-situ fabrication of novel organic nanoparticle hydrogels with excellent mechanical properties

A kind of well-defined organic nanoparticle composite polyacrylamide (PAAm) hydrogels (OC gels) are successfully fabricated using in-situ free-radical polymerization with polystyrene (PS) nanoparticles as the cross-linker. These gels show excellent mechanical properties for the uniform dispersion of the organic cross-linker which is prepared by emulsifier-free emulsion polymerization. In addition, a particular swelling behavior is also revealed due to the introduced hydrophobic PS nanoparticles. Both the mechanical and swelling properties show obvious changes with various contents of PS nanoparticle and acrylamide (AAm) monomer in the initial reaction solution. The mechanism for OC gels formation is proposed, and it is validated that the hydrogen bonding interaction among polymer chains also plays an important role in the network formation in addition to the combination of the mutual termination of the attached radical chains on vicinal particles. Besides, the facile route is feasible to design stabilized and functional hydrogels with excellent mechanical properties without affecting the original properties of hydrogels.

Designable synthesis of nanocomposite hydrogels with excellent mechanical properties based on chemical cross-linked interactions

A new type of nanocomposite hydrogels based on covalent cross-linked interactions with excellent mechanical properties and good stability has been prepared by using in situ free-radical polymerization; polystyrene nanoparticles with photo-activity are used as the cross-linking agent.

Reducing defects on multi-walled carbon nanotube surfaces induced by low-power ultrasonic-assisted hydrochloric acid treatment

A simple method to prepare multi-walled carbon nanotubes (MWCNTs) with high purity, high-aspect ratio and especially minimal defects is presented by low-power ultrasonic-assisted treatment of raw carbon nanotubes in hot concentrated hydrochloric acid under continuous reflux conditions. The evolution of surface morphology of MWCNTs during the treatment is evaluated by transmission electron microscopy, and microstructure is characterised by Fourier transform infrared and micro-Raman spectroscopy. The results show that with increasing the treatment time, the external layers with defects are peeled off piece by piece from the surface of MWCNTs until the inner graphite layers with good chemical resistance are exposed. The MWCNTs treated for less than 15 h by this method have been demonstrated to have minimal microstructural defects and large aspect ratios as compared to those treated in mixed concentrated nitric acid and sulphuric acid, which is further confirmed that almost no manganese dioxide particles can be anchored on the surface of the resulting MWCNTs due to their lack of the reactive defect sites.