Synthesis Of Polymer-silica And Carbonaceous Helical Nanomaterials Via A "Silica-assisted" Strategy

Helical nanomaterials have received considerable attention because their unique mechanical,electromagnetic and optical properties.In the previous work,single-handed helical polymer and carbonaceous nanomaterials were prepared using chiral low-molecular-weight gelators as template.Comparing to chiral amphiphilic molecule,relatively cheap achiral amphiphilic molecules unique cost advantage in the preparation of resin-silica and carbonaceous helical nanomaterials.In this work,a series of resin-silica helical nanocomposites and carbonaceous nanomaterials were obtained through introducing of co-structure directing agent.The application of the carbon materials in the anode materials of lithium-ion batteries(LIBs)battery was investigated.The main work is shown as following:Firstly,3-aminophenol-formaldehyde resin-silica helical composite nanorods and resorcinol-formaldehyde resin-silica helical composite nanofibers were obtained via a sol-gel method using cetyltrimethylammonium bromide as template,3-aminophenol,resorcinol,formaldehyde and tetraethyl orthosilicate as precursors.Experimental results show that: The diameters and lengths of the composite nanorods did not increase with the length of the alkyl chain.The co-structure directing agent plays an important role in the assembly behavior of organic and inorganic phase.Secondly,carbonaceous nanorods(CNRs-600),carbonaceous nanotubes(CNTs)and mesoporous helical carbonaceous nanofibers(CNFs)were prepared using the obtained silica-resin as starting materials,and they were used as anode materials for LIBs.The research results show that: The carbonaceous nanomaterials were predominantly amorphous carbon.The specific surface area of CNTs and CNFs are higher than that of CNRs,the specific surface area of three nanoparticles are 551.4,691.4 and 901.2 m2 g-1,respectively.The nitrogen content of CNRs-600 which obtained form 3-aminophenolformaldehyde resin-silica composite nanorods is much higher,the nitrogen content of CNRs-600,CNTs and CNFs are 7.9,1.9 and 1.7 wt%,respectively.The CNRs-600 delivered a reversible capacity of 289.3 m A h g-1 at 300 m A g-1 after 400 cycles.The discharge capacity of 510.7 m A h g-1 for CNTs and 538.0 m A h g-1 for CNFs were obtained after 400 cycles at current intensity of 300 m A g-1,which demonstrated that cycling stability of obtained carbonaceous nanomaterials is better than commercial graphite.Finally,single-handed twisted carbonaceous nanotubes with nitrogen content of 6.0 wt% were prepared via carbonization of chiral organic self-assemblies.Broad signals were observed at 200-604 nm in circular dichroism spectra,the signals were proposed to originate from the electron transfer among the aromatic rings.The carbonaceous nanotubes were formed due to the adsorption of the organic self-assemblies on the inner surfaces of the tantalum pentoxide nanotubes and the shrinkage of organic self-assemblies during the drying process and subsequently carbonization.