Monomers diacetylene substituted

It should be noted that functionalised diacetylene monomers have also been used for coupling reactions with haloarenes. By reacting diacetylene-substituted p-aminoanilines [135] and diethynyl(methyl)( -octyl)silane [136] with diiodoarenes, polyamides and polysilanes have been prepared, respectively. 

The two-step process of epitaxial polymerization has been applied to symmetrically substituted diacetylenes First, the monomers have been crystallized epitaxially on alkali halides substrates from solution and the vapor phase. The oriented monomer crystals are then polymerized under the substrate s influence by gamma-irradiation. The diacetylenes in this study are 2,4-hexadiyn-l,6-diol (HD) and the bis-phenylurethane of 5,7-dodecadiyn-l,12-diol (TCDU). The polydiacetylene crystal structures and morphologies have been examined with the electron microscope. Reactivity and polymorphism are found to be controlled by the substrate. 

Mono- and bis(pentafluorosulfur)diacetylenes, F6SC=C—C=CH and F5SC=C—C==CSF5, are obtained by the addition of F5SBr to diacetylene followed by dehydrobromination. These monomers yield interesting polymers (140). A variety of uses are proposed for several of these pentafluorosulfur-containing alkanes and alkenes, e.g., as dielectric insulators (122, 141), elastomer precursors (142), blood substitutes (143), fumigants (144), and insecticides (145). 

An example of the possiblities in this respect is the polymerization of acetylene and diacetylene derivatives, i. e. of multifunctional monomers, with several degrees of freedom in the addition to the active centre. Generally a poorly defined mixture of mostly insoluble products is formed. On the other hand, polymerization of many substituted diacetylenes in the solid phase is easy. By short-wave irradiation (UV, j>) or simple tempering below the melting... 

The outline of this article is as follows. After general remarks tUsout the solid-state polymerization process, adopting the view that it is important to develop new types of solid-state polymerization, the polymerization of the following classes of monomers will be discussed diacetylenes, monoacetylenes, vinyl and diene monomers, cyclic systems which ring open, and transition metal systems. It is implicit in the discussion that appropriately substituted forms of the above monomers may be polymerized as mono-layers and multilayers (11-13) as well as in the form of inclusion complexes (14). Emphasis will be placed on topics of current interest. 

Diacetylene monomers with aromatic groups directly bonded to the triple bonds typically do not undergo extensive conversion to polymer (64). More extensive conversions appear to take place in fluorine-substituted diphenyl diacetylenes (65), and this may be an important new vector in PDA research. 

The addition of bulky substituent groups produces large changes in conformation but the overall effect is to increase both substituted conjugated rings should not be incorporated in the substituent groups of diacetylene monomers. 

Brief reviews of the structure-reactivity relationship of dlacetylene monomers and the evolution of solution spectra after changes in solvent composition have been presented. Much remains to be done to formulate a precise set of guidelines for the production of reactive diacetylenes. The presence of multiple substitution of conjugated rings in the end groups of monomers has been shown to be unfavourable. The presence of intermediate partially ordered PDA chains in solution has been shown to occur for several nBCMU substituted polymers. A simple model consistent with the spectroscopic data is introduced. 

FTIR spectroscopy and near-infrared-FT-Raman spectroscopy were used to study the molecular stmctural transformations which occurred during thermal treatment of several nitroxyl substituted diacetylene monomers. These spectroscopic techniques were also used to investigate the solid state polymerisation reactions of the nitroxyl-substituted monomers, classic diacetylenes and of polydiacetylenes. The results were discussed. 7 refs. RUSSIA... 

If the crystal structures of the initial monomer and the polymer produced are crystallographically related, the polymerization is described as being topochemical or topotactic. Suitably substituted diacetylenes are so arranged in the crystal lattice that the conjugated triple bonds represent the steps of a ladder. Substituents linked by hydrogen bonding represent the runners of the ladder. A suitable substituent is, for example, —CH2—O—CO—NH—C6H5. A kind of shear takes place on polymerization, since the density difference between monomer and polymer crystals is small ... 

A theoretical model for predicting which diacetylene monomers will undergo topochemical polymerization has been developed. The semiempirical SCF-MO methods NfrroO, AMI, and PM3 have been used to carry out calculations based on this model. These methods were used to minimize the monomer geometries and the intermolecular distances and angles (R and a) between the monomer pairs. They have been applied to reactive and unreactive derivatives as well as some unknown derivatives. The results from these calculations suggest that this method may be applicable to a large variety of substituted diacetylene monomers. Specific examples of cases which show both the utility and the limitations of the model are discussed. 

In order for this model to be useful, programs must exist which can provide reasonable geometries for substituted diacetylenes and must properly model intermolecular interactions between monomer pairs. Ab initio programs are unsuitable for this project due to the size of the molecules involved. Since we are also interested in electronic properties as well as geometric properties, it was decided that the most suitable candidates available were the semiempirical SCF-MO methods MNDO, AMl, and PM3 . These methods are all found in the program MOP AC. It has been determined that these methods do indeed provide reasonable geometries for substituted diacetylenes 2 only... 

Finally, it was found that assumption (V) was needed to adequately model systems where the substituents are bulkier in one direction than another, i.e. rings. In many of the crystal structures of substituted diacetylenes, this assumption is valid. Certainly it should be for the reactive diacetylenes because if the rings were parallel to the stacking axis, the monomers would be pushed farther apart, leading to large d values. 

The j Aiotochemistry of Langmuir-Blodgett multilayers has been discussed (83,84) as has that of phenazine-diacetylene caid nic acid con lezes (85). y-ray polymerization of the coraplesces and pure acids have also been studied The complexes are iinusual in that the initiation can occur via a fhotochemical reaction beti een the phenazinc and acid Thermal polymerization has been reported for bis( 1,3-penta-diynl mercury (88) and a nuniber of nitrophenoxy substituted monomers (8e-91) The thermal polymerization of hexadiynediol has also been reported (92) With the exception of the LB multilayers the kinetics were not analysed in detail ... 

Striking differences of their reactivities were reported before by Ch. Krohnke [54]. The limited amount of samples available was sufficient for the permittivity analysis. Figure 9.35 shows the behaviour of different topospecifically deuterated derivatives of TS at T = 60 °C [73]. It should be stressed that the induction periods of single crystals with nominally the same history did not differ by more than 10% at the same polymerization temperature. The toposelective modification of these substituted diacetylenes by the deu-teration of the methylene groups close to the triple bonds of the diacetylene monomer (that are engaged in the crankshaft-type motion of the monomer molecule around its center of mass during solid state polymerization) evidently has a drastic influence on the sohd state polymerization. 

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