A series of poly(L-glutamate)s grafted with oligo(ethylene glycol)(OEG) side-chains through the thioether linkages(PALG n-g-EG x, x = 2, 3 and 4) were prepared by ring-opening polymerization(ROP) of γ-allylL-glutamate N-carboxyanhydride(ALG-NCA) and thiol-ene photoaddition. The chemical structures and physical properties were characterized by 1H-NMR, Fourier transform infrared(FTIR), circular dichroism(CD), etc. The PALG n-g-EG x samples with x = 3 and 4 displayed lower critical solution temperature(LCST) in water due to the presence of OEG units. The clouding point(CP) of polypeptides can be finely tuned by changing the side chain structures, molecular weights and sample concentrations. In addition, the thioether linkages in the side chains offer additional redox-responsive properties. The influence of both OEG units and thioether linkages on the LCST behavior was systematically investigated. This work provides an efficient way to prepare multi-stimuli responsive materials with highly tunable properties.
A newly natural fine template,kapok fiber,for microtube preparation was reported.Large scale microtubes with high length/diameter ratio and controllable wall thickness and morphology have been successfully fabricated with this template.It is a wildly available,low-cost,environmental friendly and fine structured natural template for microtubes.Its thin wall thickness is only about 1-2μm that means the whole template material is tiny and easy for removing.Even there is any residue the amount can be ignored.When the template is covered with a shell component,hollow structured microtube could be obtained by removing the thin inner template,and its shape could be the same as that of the original template (positive copy of the template's shape).The products have high length/diameter ratio and uniform tubular structure.By further modifying the fabricating methods,facile fabrication not only exists for polypyrrole(PPy) in electrochemical deposition,but also for many other organic and inorganic materials.The surface morphology and wall thickness of the resultant microtubes can be easily modulated by controlling the processing conditions.This natural fiber is predicted to be a fine template for fabricating large scale microtubes with large cavity and high length/diameter ratio.
