PHOSPHORUS-CONTAINING POLYMERS, THEIR BLENDS, AND HYBRID NANOCOMPOSITES WITH POLY(HYDROXY ETHER), METAL CHLORIDES, AND SILICA COLLOIDS
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Additional research has focused on the influence of these materials on the property characteristics of vinyl ester matrix resins and has shown that the concentration of phosphonyl groups controls the homogeneity of both oligomers and the resulting networks. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fracture toughness measurements further confirmed the qualitative observations.
Metal salts, such as CoCl2 and CuCl2 had earlier been demonstrated to form complexes/nanocomposites with phosphorus-containing poly(arylene ethers). It has been possible to prepare transparent films with 100 mol% of metal chlorides, based upon the phosphonyl groups. The films are transparent, unlike the opaque polysulfone control systems. FTIR results suggested the formation of inorganic salt and polymer complexes at low concentrations. TEM showed homogeneous morphology at low concentrations and excellent dispersion even at high mole % of salts. Cobalt materials reinforce the basic poly(arylene ether)s to provide higher modulus values and influence positively the char yield generated after TGA experiments in air. The cobalt salt/BPADA-DAMPO polyimide composites also yield transparent films, implying very small dimensions.
Silica-polymer nanocomposites were also produced by mixing commercial silica colloid/N,N-dimethylacetamide (DMAc) fine dispersions (~ 12 nm) with bisphenol A poly(arylene ether phenyl phosphine oxide). The dry films produced by solution casting are transparent and silica colloids are evenly dispersed (~ 12 nm) into the polymer matrix as shown by TEM. These nanocomposites increased char yield compared with the polymer control, suggesting their fire retardant character. In comparison, the silica/polysulfone hybrid films prepared by the same methods were opaque and the char yield was not improved. This different phase behavior has been explained to be due to the hydrogen bonding between phosphonyl groups and silanol hydroxyl groups on the surface of the nanosilica.
- Doctoral Dissertations