ia poly-, FRG SUMMARYHeck reactions with anthracenecontaining compounds are investigated. Some oligomeric model compounds as well as polymers were synthesized. The reason for the failure of 9.10-divinylanthracene to undergo the Heck reaction are described. The solution of the synthetic problem was achieved by using the yet unknown 9,iO-bis(i,3-butadienyl)anthracene. 1 CHCIZ 3 CHZCl 2 L a) Part 3: cf. 10). @ 1990, Hiithig & Wepf Verlag, Basel CCC 0025-1 16X/90/$03.00 Scheme 1: 2 Br 5 Br C H LI/J2 4 9 Br 6 063 Br 6 J 7To our surprise we could not observe any reaction between 9,lO-divinylanthracene (8) and any dihalogenated anthracene. This outcome cannot be due to the lack of reactivity of the dihalogen component, since the monomer 8 is obtained from

Some reactions for the synthesis of poly(phenylenevinylene), PPV, are examined for their capability to form poly(9,lO-anthrylenevinylene). The reasons for the failure of these reactions are described. Soluble oligomers with up to seven anthracene units are synthesized. The properties of the oligomers are studied and conclusions for the properties of poly(9,lO-anthrylenevinylene), PAV, are drawn. +Ar-CH=CH+, 1Our interest in the title compound, poly(9,lO-anthrylenevinylene), is based on the fact that anthracene, acting as an electrophoric subunit, is able to accept two charges in a reduction process to form a stable dianion4). Thus, poly(9,lO-anthryleneviny-1ene)s should possess exceptional charge-storage properties and electrical conductivity in the doped state. In this paper, we describe the synthesis of soluble oligo(9,lO-anthry-1enevinylene)s. Their characterization allows prediction of the physical properties of the yet unknown poly(9,lO-anthrylenevinylene). Furthermore, the synthetic methods for the synthesis of poly(p-phenylenevinylene) are examined for their applicability on the anthrylene analoga. a) Part 2 A. Results and discussion Attempted polymerizationOur primary interest lay in the direct synthesis of the polymer. Scheme I shows all of the polymerization attempts that were conducted.Of all the reactions listed in Scheme I, merely the Horner-Emmons modification of the Wittig reaction (Scheme I, a) results in structurally uniform, but very low molecular weight products (Fn = 3-4)

The high solids semicontinuous emulsion polymerization of VAc and VeoVa10 using poly­(vinyl alcohol) (PVOH) as polymeric stabilizer is investigated. It is shown that (i) PVOH strongly affects the kinetics of the process and (ii) the formation of PVOH-graft-poly­(VAc–co-VeoVa10) leads to an overestimation of the gel content and an underestimation of the sol molecular weight when the standard characterization techniques are directly applied. A new method to properly characterize the MWD of these copolymers is presented. A mathematical model is used to analyze the effects of surfactant and initiator on the kinetics and polymer microstructure.

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The temperature dependent redox decomposition rate constants of ascorbic acid (AsAc) in aqueous solutions were quantified in the presence of ammonium iron(III) sulfate dodecahydrate (Fe-cat) and tert-butylhydroperoxide (TBHP). Decomposition rates were determined in a temperature range from 35−75 °C with respect to the component ratios. First-order kinetics were observed up to specific conversions (∼20−80%) for AsAc decomposition. The application of a flexible Weibull model provided a good and comparable description (R 2 ≥ 0.992) of decomposition processes up to high AsAc conversions (96%) at all studied reaction conditions. The activation energy was determined as a function of AsAc and Fe-cat ratios (38−79 kJ mol −1 ). Statistical modeling facilitated the prediction of rate constants. Thus, it was possible to adjust the reaction rate of emulsion copolymerizations of vinyl acetate and Versa10 in a broad temperature range (10−70 °C) by variation of the Fe-cat content.

Photosensitive cholesteric polysiloxanes, which contain an azo dye, were irradiated with linearly polarized light. The cholesteric samples were oriented in the Grandjean texture. Before irradiation they reflected circularly polarized light in the near infrared region. For perpendicular incidence, only one order of reflection was observed. Upon irradiation with linearly polarized light, which is absorbed by the azo dye, additional reflection bands appeared in the visible part of the spectrum. It turned out that the additional reflection is caused by a new Bragg type grating which shows higher reflection orders. The formation of the grating is based on the periodic deformation of the helical ordering of the molecules. The deformation is periodic, as due to photoselection, only dye molecules in equidistant layers with a suitable orientation absorb radiation. For low exposure, the grating reflects linearly polarized light. After continued irradiation, the reflection bands disappear almost completely. High birefringence, strongly dichroic dye absorption and the loss of the reflecting properties prove that a planar nematic texture has developed. The formation of this texture from the Grandjean texture is a new example for photoinduced rotational diffusion.

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Much research has been done toward efficient nonlinear optical materials and their application in second harmonic generation (SHG) and in electro-optical devices." -31 Organic polymers have been of special interest because of their improved processability, their potentially large nonlinear susceptibility, their good mechanical and thermal properties and the low cost of production. Therefore, these materials are most promising for potential technical applications.Since nonlinear optical properties like SHG only appear in materials with a noncentrosymmetric structure, poling of the polymeric films in an external field is necessary. Poling can be done in a DC electrical field or by the more efficient corona poling." -41 For the poling in the DC field, the polymer has to be heated above the glass-transition temperature T, in order to enable the dipolar chromophores to orient parallel with respect to each other and to the external field. On cooling of the samples with the electrical field still on, the polar structure is frozen-in in the glassy material. The longterm stability of the resulting structure is a critical factor in view of possible technical applications.In early experiments, the NLO chromophores were only physically mixed with the polymer to form guest-host systems." -61 Doped polymers are easily produced, but generally the concentration of the chromophore is limited to rather low values and the poled, noncentrosymmetric structures suffer from relaxation phenomena which destroy the polar alignment of the chromophores. However, only recently a guest-host system showed excellent thermal stability due to an increase of T, above 200 "C. ['] A higher density of the chromophoric group and samples with improved thermal stability also result when the NLO chroniophore is chemically linked to the polymeric backbone, thus forming a copolymer.[" '* ' . '] The long-term thermal stability of some copolymers was increased via chemical cross-linking during the poling in an electric field. ["-12] Compared to organic crystals and to Langmuir-Blodgett [**I Financial support from the BMFT, pmject no. 03M4059. and from the films,", 21 the polar ordering is principally reduced in copolymers and polymeric guest-host systems due to the amorphous structure of polymeric materials. Liquid-crystalline side-chain polymers and main-chain polymers, however, combine the advantages of polymers with the favorable properties of anisotropic crystals and seem to be well suited as matrices for the polar orientation of chromophores. Both in anisotropic guest-host systems['-3. 'I and in copolym e r~[ '~. more efficient SHG was possible, which proved the advantages of anisotropic matrices.A different way to reorient the side chains was discovered when azo-dye-containing liquid-crystalline side-chain polymers were investigated with regard to their potential in optical information storage." ', 16] In this new method, continued photochemical trans-cis isomerization of the azo dye results in a reorientation of the dye molecules and the surround...