Polyphosphazene

Abstract: : The phosphazene polymer (NP(OC2H40C2H4OCH3)n, MEEP, was synthesized and amorphous solvent-free salt complexes were performed with LiSo3CF3, NaSO3CF3, Sr(SO3CF3)2, and AgSO3CF3. A material with the composition (LiSO3CF3)0.25. MEEP has a conductivity of .00008 ohm/cm at 30 C, which is much higher than corresponding poly (ethylene oxide) complexes. The phosphazene electrolytes are promising materials for ambient-temperature high energy density batteries.

Abstract: A method for encapsulating biologically-labile materials such as proteins, liposomes, bacteria and eucaryotic cells within a synthetic polymeric capsule, and the product thereof, are disclosed. The method is based on the use of a water-soluble polymer with charged side chains that are crosslinked with multivalent ions of the opposite charge to form a gel encapsulating biological material, that is optionally further stabilized by interactions with multivalent polyions of the same charge as those used to form the gel. In the preferred embodiment, hydrolytically stable polyphosphazenes are formed of monomers having carboxylic acid side groups that are crosslinked by divalent or trivalent cations such as Ca?2+? or Al?3+?, then stabilized with a polycation such as poly-L-lysine. A variety of different compositions can be formed from the crosslinked polymer. In a preferred embodiment, microcapsules are made by spraying an aqueous solution of polyphosphazene and material to be encapsulated into a calcium chloride solution. A semi-permeable membrane is formed on the microspheres by complexation of the surface carboxylate groups with poly(L-lysine).

Abstract: Current methods for the replacement of skeletal tissue in general involve the use of autografts or allografts. There are considerable drawbacks in the use of either of these tissues. In an effort to provide an alternative to traditional graft materials, a degradable 3-dimensional (3-D) osteoblast cell–polymer matrix was designed as a construct for skeletal tissue regeneration. A degradable amino acid containing polymer, poly[(methylphenoxy)(ethyl glycinato) phosphazene], was synthesized and a 3-D matrix system was prepared using a salt leaching technique. This 3-D polyphosphazene polymer matrix system, 3-D-PHOS, was then seeded with osteoblast cells for the creation of a cell–polymer matrix material. The 3-D-PHOS matrix possessed an average pore diameter of 165 μm. Environmental scanning electron microscopy revealed a reconnecting porous network throughout the polymer with an even distribution of pores over the surface of the matrix. Osteoblast cells were found attached and grew on the 3-D-PHOS at a steady rate throughout the 21-day period studied in vitro, in contrast to osteoblast growth kinetics on similar, but 2-D polyphosphazene matrices, that showed a decline in cell growth after 7 days. Characterization of 3-D-PHOS osteoblast-polymer matrices by light microscopy revealed cells growing within the pores as well as on surface of the polymer as early as day 1. This novel porous 3-D-PHOS matrix may be suitable for use as a bioerodible scaffold for regeneration of skeletal tissue. © 1996 John Wiley & Sons, Inc.