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A novel approach is presented here to prepare polystyrene/FeO multihollow microspheres with porous walls. Water-in-oil-in water (W/O/W) double emulsion was developed in mini-emulsion system with the help of amphipathic FeO nanoparticles dispersed in oil phase. A γ-ray irradiation from Co source initiated the radical polymerization and controlled the reaction degree. Most of polymerization took place in mini-droplets of monomer developed during mini-emulsification process. Therefore, every mini-droplet of monomer with water inside can act like soft template, and polymerization helps to solidify such soft template and successfully reserve and transfer the morphology of these water-in-oil mini-droplets to solid microspheres. Multihollow structure was developed after drying since water inside of microspheres evaporated. Superparamagnetic property was also confirmed by VSM characterization on nanocomposites. Finally, the mechanism of forming such structure was preliminarily elucidated. [ABSTRACT FROM AUTHOR]

Amino and other functional groups were introduced to a polyethylene substrate starting from the unsaturated pendant and bridge groups (collectively called side chains) of polyethylene, which had been prepared by γ-ray irradiation under an atmosphere of 1,3-butadiene of the polyethylene substrate (the drawn film of ultra-high- molecular-weight polyethylene, M¯v: 5 × 106). 2-Aminoethylamino groups were introduced to the side chains through treatment either with bromine or with peracetic acid vapor followed by immersion in ethylenediamine. Introduction of amino groups were confirmed by Fourier transform IR spectrometry, ninhydrin test, and acid–base titration. Starting from 2-aminoethylaminated polyethylene, modification cycles to grow a dendrimer on the film were applied; these consisted of 2-methoxycarbonylethylation and 2-aminoethylamidation. This technique resulted in hyperbranched modification of the polymer. The product is a kind of dendrimer grown on the surface of polyethylene film with amplified amino ends and has anion-exchange capacity and absorbs acid dye. Its application in practical uses is discussed. [ABSTRACT FROM AUTHOR]

Ultra-high-molecular-weight polyethylene ( M¯v: 5 × 106, 100-times elongated film) was irradiated with γ-rays under a 1,3-butadiene atmosphere at room temperature. Electron paramagnetic resonance (EPR) measurements indicated that the radicals formed on the polyethylene substrate during the irradiation were short-lived. EPR, Fourier transform IR spectroscopy, solid-state NMR, and differential scanning calorimetry of the as-irradiated materials indicated that butadiene molecules were covalently bound to the polyethylene chains as pendant groups bearing trans-vinylene and vinyl functions in a ratio of 3:1. Some crosslinks among the pendants, or between pendants and the main chains were produced. The number of unsaturated pendants introduced (including bridges) per carbon atom of the polyethylene main chain was dependent on the irradiation dose and the butadiene pressure, and was 0.096 butadiene units for 10 kGy irradiation under a 304 kPa butadiene atmosphere. The unsaturated pendants or bridges on the polyethylene chain thus introduced may be good targets to functionalize polyethylene by covalent modification. [ABSTRACT FROM AUTHOR]