To modify the surface of polymethysiloxane (PMS) -coated titanium dioxide which was modified with alcoholic hydroxyl groups (Ti/Si-R-OH), we investigated the grafting of hydrophilic polymers by the radical graft polymerization initiated by the system consisting of ceric ion and alcoholic hydroxyl groups on the surface. The radical polymerizations of acrylamide (AAm), N, N-diethylacrylamide (DEAM), and N-isopropylacrylamide (NIPAM) are successfully initiated by the surface radicals formed by the redox reaction of ceric ions with alcoholic hydroxyl groups of the surface and the corresponding polymers were grafted onto Ti/Si-R-OH : The percentage of PAAm grafting reached to 24. 9% after 90 min at 30°C. By the grafting of these hydrophilic polymers onto Ti/Si-R-OH surface, the surface wettability turned from hydrophobic to hydrophilic and the dispersibility in water was remarkably improved. In addition, the dispersibility of PDEAM- and PNIPAM-grafted Ti/Si-R-OH in water was readily controlled by the temperature of dispersant. These polymer-grafted Ti/Si-R-OH gave a stable dispersion in water at below LCST (lower critical solution temperature) of the polymers, i. e., 32°C, but immediately precipitated above the temperature.
Ester groups and hydroxyl groups of a polyester composed of 1, 4-cyclohexanedicarboxylic acid (CHDA), isophthalic acid (iPA), 1, 4 -cyclohexanedimethanol (CHDM) and 1, 5 -pentanediol (PD) have been characterized by 1H NMR quantitatively and PD centerd triad of the polyester has been characterized by 13C NMR qualitatively. The process in the polycondensation and the transesferification without catalyst was pursued with 1 H NMR and13C NMR and following results were obtained. 1) The hydroxyl groups of CHDM and PD are consumed at the almost same rate, while the carboxyl groups of CHDA and iPA are consumed at different rates at the initial stage of the polycondensation. 2) The polycondensation gives the polyester with almost randam monomer sequence. 3) Transesterification dose not occure at this condition. Consequently, alcoholysis, acidolysis and hydrolysis during the polycondensation lead to the p olyester with an almost randam monomer sequence at this condition.
Ultrahydrophobic composite films containing nickel and tetrafluoroethylene oligomers (TFEO) were formed on nickel plates by a composite electroplating method. The H2O contact angle increased with increasing electrical charge passed (Q), reaching a plateau of 142±2°once Q exceeded 2.4 C cm-2. From weight measurements and diffuse reflectance infrared spectra of films of varying thickness (d), the ratio of the surface amount of TFEO to that of nickel is revealed to increase gradually with increasing Q, when d<1.4 μm. The compositional gradient at the interface can be explained by the large difference between TFEO particles and Ni2+ ions regarding the time each species attains a constant electrophoretic velocity. The time-lag mechanism further predicts that there is generally present such a compositional gradient at the interface between metal-nonmetal composite electro-plating films and substrates. Electron probe microanalysis and Auger electron spectroscopy indicated that the surface consists of a TFEO protrusive area (-60%) and a nickel-rich hollow area (-40%). The ultrahydrophobic character of the composite film is discussed on the basis of a two component heterogeneous surface model in which the incorporation of air into the Ni-rich hollow region is taken into account.