Polymeric micro‐sequential concentric transcrystalline morphology self‐assembly,with intermittent self‐shear‐oriented amorphous layers

The investigation and understanding of polymer crystallization processes, the resulting crystalline morphologies, and the mechanism of their formation is crucial in creating materials with desired properties for specific applications. The present research introduces and investigates a new polymeric crystalline morphology, observed for the first time in this research. This newly observed morphology, is a sequentially micro‐multi‐layered concentric morphology that self‐assembles throughout the bulk polymer matrix, with intermittent self‐shear‐oriented amorphous layers. The research analyses the structure and mechanism of its formation. Polarized light microscopy studies have shown a drastic and sudden morphology change that occurred during crystalline growth. Crystalline‐growth kinetics studies performed, showed a distinct pulsatile repeating growth pattern of approximately two growth pulses per second. Thermal analysis indicated the presence of two different populations of crystalline strength. Crystalline structure was analyzed by XRD pattern measurements. It was demonstrated here, that the sequential concentric transcrystalline morphology is nucleated on a shear‐oriented amorphous molecular layer in the adjacent melt formed during and as a consequence of crystalline growth, which occurs in a micro‐periodic sequences, with intermittent self‐sheared amorphous layers. The structure was confirmed by both scanning electron microscope and reflectance microscopy. Small angle X‐ray scattering measurements of the same materials reported in literature are consistent with the melt shear‐orientation theory described earlier. The discovery of this new crystalline morphology in this research, potentially opens a new door in the vast field of material properties and applications. Copyright © 2017 John Wiley & Sons, Ltd.     

Frequency comb Vernier spectroscopy for broadband, high-resolution, high-sensitivity absorption and dispersion spectra

A femtosecond frequency comb provides a vast number of equidistantly spaced narrow band laser modes that can be simultaneously tuned and frequency calibrated with 15 digit accuracy. Our Vernier spectrometer utilizes all of theses modes in a massively parallel manner to rapidly record both absorption and dispersion spectra with a sensitivity that is provided by a high finesse broadband optical resonator and a resolution that is only limited by the frequency comb line width while keeping the required setup simple.     

Trinuclear first row transition metal complexes of a hexapyridyl, trialkoxy 1,3,5-triarylbenzene ligand

Trinuclear complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) were synthesized using a ligand architecture based upon a 1,3,5-triarylbenzene core decorated with six pyridines and three alkoxide moieties. Characterization via X-ray diffraction, NMR, and magnetism studies is discussed.     

Bimetallic effects on ethylene polymerization in the presence of amines: inhibition of the deactivation by Lewis bases

Dinickel complexes supported by terphenyl ligands appended with phenoxy and imine donors were synthesized. Full substitution of the central arene blocks rotation around the aryl-aryl bond and allows for the isolation of atropisomers. The reported complexes perform ethylene polymerization in the presence of amines. The inhibiting effect of polar additives is up to 250 times lower for the syn isomer than the anti isomer. Comparisons with mononuclear systems indicate that the proximity of the metal centers leads to the observed inhibitory effect on the deactivation of the catalysts.     

The Chiral Glycine Enolate Derivative from 1-Benzoyl-2-(tert-butyl)-3-methyl-1,3-imidazolidin-4-one is Alkylated in the 5-Position with Relative Topicity lk. Preliminary Communication

An overall enantioselective substitution of the R-group of an α-hydroxy- or α-amino acid 1 [R? CH(XH)COOH] by another R-group is possible through heterocycles 2 obtained from 1 with pivaladehyde ( 1 → 7 ). The rac- and the (S)-(+)-heterocycles 8 (title compounds of type 5 ) are prepared from glycine and O-benzyl-(S)-serine, respectively. Their enolates (cf. 9 , type 6 ) are alkylated with iodomethane, iodobutane, 2-iodopropane, benzyl bromide, and acetone to give the trans-disubstituted imidazolidinones 10 with ≥ 95% diastereoselectivity. The configuration of the products is established by chemical correlation with alanine, phenylalanine, and valine.