The structure of submicron polyethylene/silica composite particles

Abstract

A novel method for a one‐step preparation of silica/low‐density polyethylene (LDPE) composite particles has been developed recently, based on performing sol–gel polycondensation within an emulsion of LDPE dissolved in xylene and tetraethyl othosilicate which is stabilized by poly (ethylene‐block‐ethylene glycol) block copolymer surfactant (PBP), all dispersed in a basic ethanolic medium. The particle dimensions are in the sub‐micron range with diameters of 200–500 nm. Small‐angle X‐ray scattering (SAXS) measurements with contrast variation, in conjunction with other characterization methods, provide information on the inner structure of the nanoparticle's composition and inhomogeneity, which has a characteristic dimension of about 7 nm. Increase in the PBP amount and the presence of LDPE result in decrease in volume fraction of voids. The surface of the particles is heavily coated with the organic material. The crystallinity and melting behavior of LDPE is unaffected by its confinement to the particles. Copyright © 2007 John Wiley & Sons, Ltd.

Cross-linked polyethylene@silica: the first full interpenetrating network hybrid particles

“…7 In recent years we have developed a new general methodology for preparation of polymer@silica semi-IPN hybrid particles, which is based on polymerization of the inorganic monomer in the presence of the organic polymer within droplets of an emulsion: the forming silica within the nanoreactors entraps the dissolved polymer. Sub-micron hybrid silica particles representing several important families of linear polymers were prepared in that way, including polystyrene, 8,9 poly(dimethylsiloxane), 10 polyethylene (both of low and high densities), 11,12 polyethyleneblock-poly(ethylene glycol), 11 and the biocompatible silica hybrids of poly(ethylene glycol) (PEG) 13 and poly(L-lactic acid). 14 The emulsion-polymerization procedure for the hydrophobic polymers utilized an O/W emulsion where the oil phase is composed of the precursor for the silica matrix, tetraethoxysilane (TEOS)-which is an excellent solvent of the polymer-along with a co-solvent and the hydrophobic polymer, and where the water phase is an alkaline water-alcohol solution to which a carefully selected surfactant is added.…”