Chain Extension of Polyamide 6 Using Bisoxazoline Coupling Agents

The chain extension behaviors of 2,2′-(1,3-phenylene)bis(2-oxazoline) (MPBO) and 2,2′-bis(2-oxazoline) (BOZ) were studied to evaluate the coupling effect on polyamide 6 (PA6) in a Haake Rheocord mixer and an extruder. The coupling results showed that there existed an optimal dosage of chain extender, lack of which caused deficiency of chain extension and excess of which led to more blocking reaction. The effect of chain extension with MPBO was shown to be inferior to BOZ. When the optimum amount of chain extenders was added in PA6, the intrinsic viscosity of the polyamide 6 increased from 1.632dl/g to 1.787dl/g(MPBO) and 2.031dl/g(BOZ), respectively. The reaction time decreased very fast with an increase in the temperature. The chain-extended products dissociated at high temperature; the degradation is suggested to proceed from the onset of the chain extension reaction, as do the coupling and blocking reactions. Furthermore, the effects of MPBO and BOZ on the thermal and mechanical properties of chain-extended PA6 were also investigated.     

Novel redox-active ionic thermotropic liquid crystalline complexes of polyelectrolyte and ferrocenyl surfactants

Redox-active polyelectrolyte-surfactant complexes(PSC) were prepared via the ionic self-assembly of sodium poly(styrenesulfonate) (PSS) and ferrocenyl surfactant,(11-ferrocenylundecyl)trimethylammonium bromide(FTMA) in aqueous solution. The PSS-FTMA complex exhibited an ordered interdigitated monolayer mesomorphous structure with the long period of d = 3.13 nm,and was in the ionic thermotropic liquid crystal SmA state at room temperature.Interestingly,in the solid complex, the ferrocenyl moieties formed H-aggregation showing an increase in theπ-π~* energy transfer of cyclopentadienes in the ferrocene moieties as known from the blue-shift in the UV spectrum.The complexes showed higher thermal stability compared with their components due to the ionic interaction.The PSS-FTMA film had a good redox reversibility,which promised to be used in electrochemical sensors.     

Theoretical study on behaviors of 1s22s-1s2 np transition for Co24+ ion in the whole energy region

Science China Physics, Mechanics & Astronomy - Non-relativistic energies of 1s22s and 1s2 np (n?9) states for Co24+ ion are calculated by using the full-core plus correlation method. Our...     

Segmented circular LD arrays side-pumped a Nd:YAG laser rod

We design a Nd:YAG module with symmetrical LD side-pumped structure in a periodical arrangement between circular LD arrays and holders. This novel design has great potential to be used in compact and miniature laser systems. Design optimization and simulation on thermal effects have been performed. An experiment has also been carried out. The experiment results indicate the all-solid-state laser with the-Nd:YAG module can stably operate in the range of 10–30 Hz with no controlling temperature by TE cooler. The laser beam had a divergence angle less than 3.8 mrad and a maximum output pulse of 174 mJ has been obtained at the pump current of 50 A and working frequency of 23 Hz, corresponding to optical-optical conversion efficiency of 40.2%.     

Adsorptive removal of Eu(III) from simulated groundwater by GMZ bentonite on the repository conditions

Journal of Radioanalytical and Nuclear Chemistry - This study investigated the adsorption of Eu(III) from simulated Beishan groundwater onto Gaomiaozi bentontie. The effects of shaking time,...     

An efficient and scalable process to produce morpholine-d8

Incorporation of isotopes has long been used as a research tool to label carbons and elucidate biochemical pathways. More recently, H→D exchange has led to analogs of therapeutic agents with improved metabolic stability and properties. Such compounds also have the potential for an improved drug/drug interaction profile and may even avoid the formation of toxic metabolites. Hence, a clear need for an efficient access to deuterated intermediates on large scale has emerged. In the context of an ongoing drug discovery program, we required large quantities of morpholine-d₈. We herein report the successful optimization of a one-pot process allowing a near complete exchange of all methylene hydrogens in morpholine to deuterium atoms using D₂O as the sole source of deuterium and Raney Nickel as catalyst. This facile and safe protocol will be used to scale up the synthesis of morpholine-d₈ in due course.     

Long pulse duration of the UV laser with a multi-reflected cavity: Experiment and modeling

The long pulse operation of ultraviolet (UV) laser attributed to multi-reflection is presented on an acousto-optic (AO) Q-switched ultraviolet laser system blocking green light inside a cavity. The ultraviolet laser with the highest average power of 456 mW is obtained with 20 kHz repetition-rate. The numerical simulation of UV pulse broadening was studied using Gaussian curve approximation. The conclusion suggests that the short multi-reflected cavity and high incident pump power will be beneficial to alleviate the width broadening effect. The results, for the first time, would provide the technology for controlling the pulse width of an AO Q-switched DUV laser.     

Influence of the Acetamide from Acetonitrile Hydrolysis in Acid-Contained Mobile Phase on the Ultraviolet Detection in High Performance Liquid Chromatography

The paper presents the influence of acetamide on ultraviolet detection after generation of acetonitrile by hydrolysis in the presence of trifluoroacetic acid in the HPLC mobile phase. The acetonitrile, with added varying contents of trifluoroacetic acid and water, was determined by GC–MS at various times. The results showed that the concentration of acetamide increased approximately linearly with time. Using a mixed standard sample solution and a model mobile phase of acetonitrile-water-tri-fluoroacetic acid (25:75:0.3, v/v) after 0, 24 and 48 h, the influence of the hydrolyzate acetamide on HPLC detection was investigated at the wavelength of 205–220 nm. The results showed that the limit of detection (LOD) of standard sample lost about 30 % after the mobile phase was placed 48 h. It is suggested that the acid-containing mobile phase was placed no more than 24 h for HPLC trace analysis at the wavelength of 205–220 nm.