Synthesis and structural characterization of novel, fluorinated poly(phthalazinone ether)s containing perfluorophenylene moieties

Study of the Effects of the Structure of Phthalazinone’s Side-Group on the Properties of the Poly(phthalazinone ether ketone)s Resins

The application of poly(phthalazinone ether ketone)s (PPEKs) resin containing phthalazinone moiety is limited, due to its poor thermoforming processability. To investigate the effects of the phthalazinone’s side-group on the thermal stability and processability of the resin, a series of PPEKs resins with different side-group (–H/–CH₃/–Ph) were prepared by nucleophilic aromatic substitution polymerization. The properties of the obtained resins were investigated by differential scanning calorimetry analysis (DSC), thermogravimetric analysis (TGA), dynamic thermomechanical analysis (DMA), and rheogoniometer. The results show that the introduction of methyl or phenyl into the PPEKs resin, significantly reduced the melting viscosity of the resin, but resulted in a slight decrease in the thermal stability of it. This might be due to the presence of methyl or phenyl, which enhanced the free volume of the molecule and reduced the entanglement between the chains; the results of the computer simulation confirmed it. Moreover, the resin films displayed excellent tensile strength with the introduction of methyl or phenyl. In a word, a novel poly(phthalazinone ether ketone)s resin with thermal resistance, easy processing and excellent mechanical properties could be obtained by introducing appropriate bulk-rigid side-groups into the phthalazinone moiety.

Chemical Alteration of Poly(tetrafluoroethylene) TFE Teflon Induced by Exposure to Electrons and Inert-Gas Ions

In this study the chemical alterations of poly(tetrafluoroethylene) (TFE Teflon) by approximately 1.0-keV electrons and 1.0-keV He and Ar ions have been examined using X-ray photoelectron spectroscopy (XPS). The initial F/C atom ratio of 1.99 decreases to a steady-state value of 1.48 after 48 h of electron exposure. Exposure to either He+ or Ar+ decreases the initial F/C atom ratio from approximately 2 to a steady-state value of 1.12. The high-resolution XPS C 1s data indicate that new chemical states of carbon form as the F is removed and that the relative amounts of these states depend on the F content of the near-surface region. These states are most likely due to C bonded only to one F atom, C bonded only to other C atoms and C that have lost a pair of electrons through emission of F-. Exposures of the electron-damaged and He+- or Ar+-damaged surfaces to research-grade O2 result in chemisorption of very small amounts of O indicating that large quantities of reactive sites are not formed during the chemical erosion. Further exposure to the electron or ion fluxes quickly removes this chemisorbed oxygen. Exposure of the He+-damaged surface to air at room temperature results in the chemisorption of a larger amount of O than the O2 exposure but no N is adsorbed. The chemical alterations due to electrons and ions are compared with those caused by hyperthermal (approximately 5 eV) atomic oxygen (AO) and vacuum ultraviolet (VUV) radiation. The largest amount of damage is caused by AO followed by VUV, inert-gas ions, and then electrons.