Diacetylene Polymerizations

Olmsted JI, Strand M (1983) Fluorescence of polymerized diacetylene bilayer films. J Phys Chem 87 4790 1792... 

Diacetylene monolayer photopolymerization was found to be topochemical it only occurred in the two-dimensional solid state of the surfactants. Polymerized diacetylenes, both in monolayers and in LB films, were found to be rather rigid and prone to cracking [160]. This undesirable property somewhat limits the exploitation of polymerized diacetylene LB films for potential electronic applications. 

Due to the topochemical restrictions of diacetylene polymerization, diacetylenic lipids are solely polymerizable in the solid—analogous phase. During the polyreaction an area contraction occurs leading to a denser packing of the alkyl chains. In addition to surface pressure/area isotherms the polymerization behavior of diacetylenic lipids containing mixed films give information about the miscibility of the components forming the monolayer ... 

The latter effect can be explained by taking into account that a partially polymerized diacetylene crystal is a molecular crystal containing dopant molecules with lower lying optical transition acting as traps for monomer excitations . Take k as the rate constant for non-radiative energy transfer from a donor to a trap, Tq as the intrinsic donor lifetime, and c, as the relative trap concentration, then the lifetime of a donor in presence of traps would be T = -I- k cj Since the probability that an excited... 

Another potential application of fully converted polydiacetylenes is based upon their unusual non-linear optical properties. Sauteret et al. found that the third order susceptibilities of TCDU and TS increases by about a factor of 600 upon polymerization and become comparable to those of inorganic semiconductors like GaAs or germanium. This is a consequence of the increase of n-electron delocalization upon polymerization. Polymeric diacetylenes can therefore be used as efficient elements for third harmonic generation. In Ref. this effect has been employed for tripling the frequencies of 1.89 pm and 2.62 pm radiation. 

A polymerizing diacetylene crystal can be considered as a composite material with large differences in the mechanical properties of both components. In such a material the mechanical properties will not only depend on the relative amount of the components but also very strongly on the geometrical arrangements of the structural elements Two limiting cases can be considered The first model consists... 

Langmuir-Blodgett films may have value in many applied areas of traditional interest to the industrial chemist, such as adhesion, encapsulation, and catalysis. The permeability characteristics of monolayer assemblies may also find application as synthetic membranes for ultrafine filtration, gas separation, and reverse osmosis. For example, Albrecht et al. (44) proved the eflSciency of polymeric diacetylene monolayers on semipermeable supports in reducing the flow of CH4. One interesting possibility lies in using LB monolayers as lubricants in magnetic tape technology. Unpublished reports have indicated that frictional coeflScients can be reduced markedly when the tape is coated with a few monolayers. In applications such as those listed previously, difiSculties may well be encountered with the mechanical stability of the films. To date, relatively little research has been carried out in this area. 

Molecular interactions between D-glucolipids and multilayered vesicles were also demonstrated with partially polymerized diacetylene units. Red vesicles constructed by sonication and subsequent UV irradiation formed a red precipitate with Con A which was redissolved by methyl-D-mannopyranoside to regenerate a red solution . ... 

The transient absorption is also shown in Figure 8 for a partially polymerized (broad line) and fully polymerized diacetylene crystal (narrow line). 

The storage and reactivity of electroactive molecules in polymerized diacetylene vesicles was the subject of studies reported by Stanish, Singh, and coworkers [109, 110], They entrapped ferricyanide in large unilamellar vesicles of photopolymerized PCg PC (1 - palmitoyl - 2 - (tricosa - 10,12-diynoyl)-OT-glycero-3-phosphocholine). Cyclic voltammetry was used to demonstrate that the ferricyanide was electrochem-ically isolated by the poly(lipid) bilayer [110]. At pH7 and 25°C, an anomalously long half-life of 2.4 weeks was calculated for Fe (CN)g- retention in polymerized vesicles. In a subsequent study [109], vesicles with entrapped ferricyanide were prepared from 2-bis(10,12-tricosadiynoyl)-OT-glycero-3-phosphatidylcholine (DCs.gPC) doped with a disulfide-capped lipid (Af-3-(pyridyl-2-dithio)propionyl-2-... 

Another example of cross-linked monolayers is that of polymerized diacetylenic thiols. Well-packed monolayers of such thiols, HS(CH2)ioC=CC=C(CH2)ioCOOH, can be polymerized in situ by UV irradiation. The polymeric structures obtained are extremely robust and durable compared to similar monomeric layers. They can be repeatedly (more than 30 times) scanned between potentials —0.5 to —1.4 V in 0.5 M KOH without any appreciable signs of desorption. Heating of the films to 200 °C for 1 h showed only ca 15% decrease in the IR intensities of the CH2 peaks, and exposure to 1 M KOH at 100 °C did not affect the integrity of the monolayer306. 

Polymerized diacetylenes show remarkably improved stability as compared to monomeric gold-thiol monolayers (see Section VI). 

That this is, in principle, possible was shown for polymerized diacetylene monolayers, the red-orange color of which was visible with the naked eye Day, D. and Ringsdorf H. (1978) J. Potym. Sci. Polym. Lett. Ed., 16, 205. 

Photoactive polymers poly(phenylene vinylene) (15), poly-p-phenylenes and polyacenes (16), photo-oxidation of electroluminescent polymers (17), and uv-polymerized diacetylene (8)... 

Figure 8 Light-induced intrafilm polymerization diacetylene-containing thiolate self-assanbled monolayers.

As an example of the use of a supramolecular synthon in materials design, we consider solid state diacetylene polymerization (see to the right). Single crystals of some diacetylene derivatives can be photopolymerized to produce long conjugated chains within the crystal. Because of their extensive conjugation, such polymerized diacetylenes have novel optical and electrical properties. For polymerization to occur, the diacetlyene must crystallize in a specific geometry that is conducive to polymerization—the potential reactive centers must be near each... 

The incorporation of the ATPase into monomeric and polymeric diacetylene liposomes is achieved by simple incubation. However, there is a remarkable difference in the ATPase activity depending on the proteoliposome preparation technique (fig. 19). If ATPase is incorporated into already... 

Fig. lO Folymer chain absorption energy for a nunber of partially polymerized diacetylenes over the ten rature range 2 to 400 K. 

POLYMERIZED DIACETYLENE MONOMERS IN MONOLAYER AND MULTILAYER FILMS, CHARACTERIZATION and POSSIBLE APPLICATIONS... 

Figwc8.9 Full Raman spectrum for the cross-polymerized diacetylene-urethane copolymer (after [67,68])... 

Figve 8.11 The effects of stress concentrations on the peak position of the C=C Raman band for a 3 mm thick cross-polymerized diacetylene-urethane plate deformed in tension. The data were obtained from spectra obtained at the different positions indicated (after [69])... 

Figure IQ, Temperature dependence of the optical absorption in partially polymerized diacetylene monomer crystals the level of conversion was generally less than 1%, after (129).

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