Morphological study of chain-extended growth in polyethylene: 3. Annealing of solution-grown lamellae
Abstract Solution-grown lamellae of three commercial polyethylenes of differing molecular weight ranges have been annealed on substrates at high pressures. The polymers transform to the new high-pressure phase before melting but the new lamellar thicknesses reached remain much below those found for the bulk material. Electron diffraction patterns support the identification of the new phase as hexagonal and it is concluded that the effects of annealing polyethylene in an unusual context are close to those which would have been produced by local melting followed by rapid recrystallization.
Abstract Asymmetric total synthesis of small ring macrolide stagonolide-E has been described in this communication. The main highlight of our synthetic strategy is the application of ME-DKR (metal enzyme combo dynamic kinetic resolution) reaction, asymmetric reduction with Noyori’s BINAL-H reagent system, stereoselective cross metathesis, and RCM (ring closing metathesis) reaction at a late stage enables us to achieve the synthesis of the target molecule in an efficient way.