The crystallization behavior and thermal properties of the polycarbonates were studied using X-ray diffraction (XRD), Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Surface tension measurements
confirmed that the critical micelles concentration of polymeric micelles were concentration ranges, which varied from about 2-70 mg/L to 5-40 Z-DEVD-FMK mg/L with increasing PEO/PPO composition ratio from 0.8 to 1. Dynamic light scattering (DLS) experiments showed bimodal size distributions, the aggregates size increased with increasing the concentration of the polycarbonates aqueous solutions. The size of the aggregates acquired from TEM was smaller than that from DLS owing to the fact that TEM gave size of the aggregates in dry state rather than the hydrodynamic diameter. The degradation process revealed that the degradation rate of the aggregates could be accelerated with an increase in temperature. Moreover, the more the polycarbonate was hydrophilic, the faster click here was its degradation. Rheological measurements Suggested that these multiblock polycarbonates were thermo-responsive and by regulating the PEO/PPO composition ratio they Could form a gel at 37 degrees C. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 1425-1435, 2009″
this work we investigated the structural and electrical properties of titanium dioxide (TiO(2)) nanotubes (NTs) grown by electrochemical anodization of Ti metal sheets in NH(4)F+H(2)O+glycerol electrolyte at different anodization voltages (V(a)) and electrolyte composition. Our results revealed that TiO(2) NTs can be grown in a wide range of anodization voltages from 10 to 240 V. The maximum NH(4)F acid concentration, at which NTs can be formed, decreases with the anodization voltage, which is 0.7% for V(a)< 60 V, and decreases to 0.1% at V(a)=240 V. Addition of water to the electrolyte results in an increase in NT growth rate and modification of NT film morphology. Glancing angle x-ray diffraction
experiments show that as-grown amorphous TiO(2) transforms to anatase phase after AG-120 cost annealing at 400 degrees C and further transforms to rutile phase at annealing temperatures above 500 degrees C. Samples grown in 30-120 V voltage range have higher crystal quality as seen from anatase (101) peak intensity and reduced linewidth. The electrical resistivity of the NTs varies with V(a) concentration and increases by eight orders of magnitude when V(a) increases from 10 to 240 V. The resistivity is also greatly dependent on H(2)O concentration increasing with its concentration up to nine orders of magnitude. Temperature dependent I-V and photoinduced current transient spectroscopy were employed to analyze electrical properties and defect structure on NT samples.