Novel tectocapsules were prepared by interfacial assembly and covalent cross-linking of poly-(divinylbenzene-alt-maleic anhydride) microspheres at the oil-water interface. Dispersions of the anhydride-functional microspheres in a range of organic core solvents, including xylene and propyl acetate and their mixtures, were in turn suspended in a continuous aqueous phase. Addition of polyethylenimines with number average molecular weights ranging from about 200 to about 100 000 to the aqueous phase led to the formation of up to 200 µm diameter tectocapsules, having walls comprised of cross-linked microspheres. The effects of microsphere loading, composition and solubility parameter of the core solvents, type of amine, and rate of amine addition on wall morphology are discussed.
Porous and amphiphilic polymer microspheres were incorporated into polyurea capsules
in order to control the release of the core solvents independently of wall formation. While nonpolar poly(divinylbenzene-55) microspheres were simply encapsulated along with the xylene core solvent, the
amphiphilic poly(divinylbenzene-55-alt-maleic anhydride) microspheres, as well as maleic acid functionalized poly(divinylbenzene-55) microspheres, became embedded at the polyurea−water interface. Release
of xylene from these microcapsules into air was monitored at room temperature and 50 °C. Release profiles
change significantly upon addition of amphiphilic porous microspheres, with the release rates scaling
with microsphere loading. Scanning transmission X-ray spectromicroscopy (STXM) indicates that the
polyurea is largely excluded from the pores of the microspheres.
A ternary library of 64 ZnO/CuO/CuCl(2) impregnated activated carbon samples was synthesized and screened automatically using a combinatorial (combi) method. The ability of the samples to adsorb toxic gases was screened gravimetrically. The stoichiometric ratio of reaction (SRR) between the moles of toxicant and the total moles of impregnant was obtained from the calculated mass increase of the samples after chemisorption, with a high SRR indicating high efficiency of toxicant removal. The combi samples that exhibited good dry SO(2) and NH(3) adsorption were prepared in bulk using the incipient wetness method and were evaluated for multigas respirator function by dynamic adsorption studies of SO(2), NH(3), HCN, and C(6)H(12) gases in either dry or humid conditions at ambient temperature. The bulk samples showed equivalent gas adsorption capacities when exposed to the different challenge gases indicating the value of the combi method for initial screening. Cu(2)Cl(OH)(3) was identified to be a potential multigas adsorbent.
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