Miriam F. Beristain

Polymerization of Diphenylbutadiyne by Gamma Rays Irradiation in the Molten State

Diphenylbutadiyne was irradiated with Gamma ray in the molten state (90°C), and its polymerization process was studied. The amorphous product has a number average molecular weight of around 1300. The yield reached around 20% with a dose of 3000 kGy, which is far greater than that in the case of irradiation in the solid state at room temperature. From the number of spins and molecular weights the product is thought to be mainly composed of cyclic oligomers. The third order nonlinear optical susceptibility of the products was found to be 3–6 × 10−10 esu determined by the Z-scan technique.

Thermal Reactions of Aromatic Diacetylenes: An Insight to Amorphous State Polymerization of Diacetylenes

Several aromatic diacetylenes were heated in molten state, and the formation of diradicals was studied by ESR spectroscopy. Intense ESR signals were observed even at temperatures as high as 180°C. The formation of radical species at such low temperatures was explained by the formation of oligomeric species. The numbers of unpaired electrons in the molten state reached to 1021 electrons per mole of diacetylene, when heated to 180°C, and deep red materials were obtained. Surprisingly the radicals did not disappear when exposed to air showing that the radicals are stable in air.

Diacetylene-containing polymers XII. Synthesis and characterization of dye-containing poly(hexa-2,4-butadiynylenoxydibenzoates)

Abstract - Several novel diacetylene-containing polymers containing diacetylenic groups in the main chains and dyes in the side-chains were synthesized using para- and meta- propargyloxybenzoic acids and four azo dyes. The polymers were synthesized by the oxidative coupling polymerization of dye-containing bisacetylenic monomers, and were characterized and their thermal properties examined. All of the polymers gave thin films with excellent optical quality by casting or spin coating. They showed Tg at around 100°C and the diacetylenic groups cross-linked on heating at above 160°C. The UV-irradiated spin-coated films were no longer soluble in the solvent and did not even swell or come off from the substrate, indicating that the films cross-linked completely.

Diacetylene-containing polymers. XV. Synthesis and characterization of poly(dipropargyloxybenzoates) containing Disperse Red 1

In order to obtain novel polymers having a very high chromophore density, dipropargyloxy benzoic acids converted to benzoates containing an azo dye, Disperse Red 1, were synthesized and characterized. 2,6-Dipropargyloxy benzoic acid could not be obtained. The bisacetylenic monomers were then polymerized by oxidative coupling reaction. Amorphous polymers with an inherent viscosity of around 0.3 in N-methylpyrrolidone (NMP) were obtained. The polymers were soluble in polar solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. The solutions in DMF caused precipitation due to the agglomeration of the dye groups on standing for a few days, but the precipitated polymers became soluble again in NMP. The UV irradiation on the spin-coated films at 80 °C cross-linked the films to convert them to thermoset resin films.

Polymerization of Diphenylbutadiyne Derivatives in Solution by Free Radical Initiator

In order to study free radical reactions of aromatic diacetylenes, the reaction of diphenyldiacetylene with di‐t‐butylperoxide was carried out in 1,2‐dichlorobenzene. The presence of t‐butoxy radicals considerably accelerated product formation, and oligomers with number average molecular weights of 700–2000 were obtained. There is no fragment of the t‐butyl group in the oligomers obtained according with the 1H‐NMR spectrum. Furthermore, it is impossible that the t‐butoxy radicals would have initiated the oligomerization. The intense ESR spectra observed during the reaction at 130°C are due to the diradicals of oligomeric diphenylbutadiyne. It was concluded that the oligomerization proceeds via coupling of diradicals, and not the successive addition of radicals to monomers. The purified product oligomers did not contain carbonyl groups indicating there was no oxidation, and their ESR spectra have revealed that these oligomers contained a substantial amount of living free radicals stable in air at room temperature. The reason why high polymers are not obtained is the steric effect of oligomeric diradicals for coupling, as well as probable cyclization.

Orientational Properties in Nonlinear Optical Polymers of Azo-Containing Poly(dipropargyloxybenzoates)

ABSTRACT We discuss the second harmonic generation (SHG) properties for the newly synthesized ortho- and meta-polymers containing dipropargyloxybenzoates in the main chain and Disperse Red 1 in the side chain with an in-situ SHG measurement. The second harmonic signals for the ortho-polymer gradually increased with time for more than 2 hours and reached to a high signal level, while the ones for the meta-polymer quickly saturated at a low signal level. This result indicates that the ortho-polymer was aligned more easily than the meta-polymer, which leads to the larger order parameter and the larger SHG coefficients for the ortho-polymer.

Synthesis of a diacetylene-containing polyisophthalate and its third-order nonlinear optical susceptibility

Abstract In order to obtain amorphous thin films of a polydiacetylene, a polyisophthalate containing a push–pull diacetylene chromophore was synthesized by the reaction of p-(N,N-diethanolamino)-p’-nitrodiphenylbutadiyne with isophthaloyl chloride in anhydrous 1-methyl-2-pyrrolidone. The polymer was soluble in organic solvents, such as chloroform, tetrahydrofuran, dimethylformamide, etc., and films with good optical quality were obtained by spin coating from its N-methyl-2-pyrrolidone solution. It was characterized by 1H-NMR, IR, DSC, UV–Visible, X-ray, etc. The diacetylene groups underwent polymerization in the film when irradiated with UV light at 120 °C under Ar atmosphere, and it contained free radicals with a radical concentration of 1016 radicals/g. The third-order nonlinear optical susceptibility, χ(3), of the polymer film measured by the Z-scan technique at 1064 nm was not noticeable, but when the film was heated and irradiated with UV light, a χ(3) value of 6.4 × 10−10 esu was obtained due to increase in π-conjugation by the formation of polydiacetylene in the side chain.