Star-Shaped Poly(2-methyl-2-oxazoline) Using by Reactive Bromoethyl Group Modified Calix[4]resorcinarene as a Macrocyclic Initiator

Summary Star-shaped poly(2-methyl-2-oxazoline) (POZO) was prepared by ring-opening polymerization of 2-methyl-2-oxazoline from a novel calix[4]resorcinarene with reactive bromoethyl groups (8Br-CX4) as an initiator. The core-first method, which uses an active multifunctional core to initiate growth of polymer chains, was applied for synthesis of star-shaped POZO based on 8Br-CX4. The obtained star-shaped POZOs were characterized by ¹H NMR, ¹³C NMR, FT-IR and DSC. From ¹H NMR, DLS and fluorescence measurements, the star-shaped POZOs formed nanometer scale micelles in aqueous media composed of hydrophobic calix[4]resorcinarene moieties and hydrophilic POZO groups.     

Enhanced nanoparticle formation by indentation and annealing on 2 MeV Cu ion-implanted SiO2

Enhancement of surface plasmon resonance (SPR) in optical absorption has been found on Cu ion-implanted SiO₂ substrate modified by micro-indentation and post-annealing. Micro-indentation effects on surface plasmon resonance (SPR) in optical absorption have been studied to control nanoparticle formation in Cu ion-implanted SiO₂ substrate. The SiO₂ was firstly implanted with 2 MeV Cu²⁺ ions at an ion flux of 4 μA/cm², up to a fluence of 6 × 10¹⁶ ions/cm². After the ion implantation, dot-array patterns of micro-indents were made by a micro-Vickers hardness tester, and followed by annealing at 600 °C in vacuum for 1 h. The optical absorption spectra of the indented region and the non-indented flat region were measured and compared with each other. After post-annealing at 600 °C, the indented area showed higher absorbance of SPR at 2.2 eV than that of the flat region annealed under the same annealing conditions. The TEM study shows larger and denser Cu precipitates inside the indentation than those in the flat area. The results indicate that the defects produced by indentation enhance the atomic migration in the plastic zone during thermal relaxation process, resulting in promoting the enhanced precipitation of Cu nanoparticles.