New electroluminescent, PPV-like, conjugated polymers containing bipyridylene−vinylene subunits were prepared and characterized with respect to their electrooptical properties. The polymers were found to exhibit reversible and tunable optical properties depending on protonation−deprotonation processes. pH sensitivity and reversible tunability of the polymers were observed by photo- and electroluminescence, optical absorption, photoinduced-absorption, and electroabsorption experiments. A luminescence red-shift of as much as 0.2 eV (∼60 nm) was observed upon full protonation of a free-base film. Films of the free-base form of the new polymers showed, in general, sharper spectra than the corresponding protonated films, probably due to increased disorder and stronger interchain interactions in the latter.

SYNOPSISThin, pinhole-free, highly adhering films for advanced technology applications can be deposited through plasma polymerization, a low temperature, solvent-free process. This research studies the influence of plasma environment (power, pressure, and monomer mass flow rate (F,) ) on the plasma polymerization of hexafluoropropylene (HFP) using a common industrial parallel-plate plasma reactor. The deposition and structure of the transparent, yellow, and highly adhering plasma polymerized H F P (PPHFP) film are investigated. The rate of polymerization (R,) increases with power ( W ) and reaches a plateau when the plasma changes from energy starved to monomer starved while the rate of etching (Re) continues to increase. The rate of deposition (Rd), the difference between R, and Re, increases with W , reaches a maximum, and then decreases. In a monomer starved plasma Rd increases with F,,, or pressure through a more efficient utilization of the energy supplied a t a given W or even a t a given W/F,. The abstraction of F and the preferential scission of the C -CF3 bond can explain the F/C ratio of 1.5, the significant amount of double bonds, and the relative lack of CF3 in a PPHFP that consists of CF3, CF2, and CF groups. A gas phase dominated polymerization produces submicrometer particles some of which agglomerate into spheres. Both the particles and the spheres deposit on the surface and are incorporated into the film with further polymerization. 0 1995 John Wiley & Sons, Inc.

SynopsisEthylene polymerization on chalk surface under the action of TiC1,-organoaluminium compound systems yields filled composites possessing high stress-strain properties and preserving their ductility up to the chalk content of 60-70 wt %. The kinetics of the process and the properties of the composites have been investigated, as well as the interrelation between catalyst fixation technique, polymerization rate, and the ductile properties of composites containing 50 wt % of chalk. The conditions leading to the formation of "homogeneous" composites with a high ductility are examined. The possible causes of the formation of composites with a low value of elongation at break are analyzed. The principal regularities of the mechanical behavior of composites are considered for the case when the process is taking place on the filler surface and leads to " homogeneous" composites. INTRODUCTIONEthylene polymerization in the presence of mineral fillers under the action of organometallic catalysts yields ultrahigh molecular-weight polyethylene (UHMWPE)-chalk composites, combining a high ductility with sufficient stiffness. 2 it has been shown that, in order to obtain composites with high values of elongation at break (c) at high filling levels (cp), the polymerization process must be localized on the filler surface. This can be accomplished, e.g., by using kaolin-fixed one-component catalysts that are active exclusively on the alumina-silica surface.One-component organometallic catalysts are inactive in the presence of chalk,2* whereas two-component TiCl ,-based systems allow obtaining highly ductile PE-chalk Moreover, as we have established,6 the stress-strain properties of the best specimens of such composites are not inferior to those of the "homogenous" composites described in Ref. 2. The E of the former is preserved at a level of 350-450% up to cp = 60-70 wt %, and their ultimate tensile at and yield strength up are sufficiently high (Fig. 1).Presented in this paper are the results of studying the interaction of TiCl, and organoaluminium compounds (A1Et2C1, AlEt,, Ali-Bu,) with the chalk surface, as well as the effect of the way the catalyst has been fixed on the chalk surface upon the kinetics of ethylene polymerization. The interrelation over Na wire. Ethylene of "polymerization purity," after additional purification from oxygen and water in columns with pyrolusite and molecular sieves, contained no more than 20 ppm of H,O and 10 ppm of 0,.TiC1, of "special purity" grade was refluxed over copper chips with subsequent distillation. Organoaluminium compounds were used without any additional purification after analyzing for the Al, R groups, and chloride content.The interaction of TiCl, with organoaluminium compounds was studied in heptane. After the specified reaction time the filler was separated from the solution and dried in u m m a t 60°C.The Ti and Al content in solution and on the filler surface was determined colorimetrically after extraction with 4N H,SO,, and the chloride content, by means of the Folgard ...

No abstract

The preparation and optical characterization of a novel PPV derivative displaying reversible tunable photophysical and electrophysical properties, poly-(5-vinylene-5'-(vinylene-1 ,4-phenylene)-2,2'-bipyridine), p-BVP, (1), is reported and its application in the preparation of tunable organic electroluminescent devices is described. The photophysical properties of the new polymer, such as its absorption, emission and electroluminescence are sensitive to the presence of even minute traces of vapors of different acids and bases such as ammonia, formic acid and haloacids. The acid/base vapor induced optical changes are reversible and can be repeated many times without any significant degradation of the optical and mechanical properties of the films. Intermediate spectra can be generated simply by controlling the exposure time of the films to acidic or basic vapors. Similar effects were observed for two other polymers, poly-(5-vinylene-5'tri-(vinylene-1 ,4-phenylene)-2,2'-bipyridme), p-BTYP, (2), and its random analog p-BRTVP, (3). The tunability of the photo-and electrophysical properties of the polymers originates probably from structural (intra-and mterstrand) changes associated with protonation-deprotonation processes and aggregation phenomena.