Molecular structure and photosensitivity of polyesters with conjugated double bonds

Photocrosslinkable polyesters of m- and p-phenylenebis(α-cyanoacrylic acids) ( I-a and I-b ), m- and p-phenylenebis(α-cyanobutadiene carboxylic acids) ( I-d and I-e ), p-phenylenebis(acrylic acid) ( I-c ), and p-phenylenebis(butadiene carboxylic acid) ( I-f ) were prepared, and their photosensitivities were investigated. The spectral sensitivities of I-a , I-c , I-d , and I-e ranged up to 365, 385, 510, and 560 nm, respectively. This order corresponds to that of λ_max due to the π-π^* transition in their absorption spectra. I-e was sensitive to the visible part of argon ion laser even in the absence of photosensitizer. The highest sensitivity observed with I-e was estimated to be 1.5 mJ/cm². In contrast, the sensitivity of I-c was low (> 10⁵ mJ/cm²) and that of I ′- d , a modified I-d , was 1300 mJ/cm², respectively. Addition of 2,6-di(4′-methoxyphenyl)-4-(4′-n-amyloxyphenyl)thiapyrylium perchlorate to them extended their sensitivity range, improving their sensitivity values to 35 and 110 mJ/cm², respectively.     

Synthesis and properties of two new series of isomeric liquid crystalline polyesters with conjugated double bonds

Two homologous series of flexible main chain liquid crystalline polyesters with isomeric mesogenic groups containing conjugated double bonds, were synthesized and studied by differential scanning calorimetry and optical microscopy. One series (S1) has the p-phenylene-diacryloyloxydibenzoyl moiety as a mesogenic unit. The other (S2) has the terephtaloyl dioxydicinnamoyl moiety as a mesogenic unit. The reactivity of the conjugated double bonds of the p-phenylenediacryloxy unit, at the temperature of mesophase formation, impedes the stability of liquid crystalline mesophases of polymers of series (S1). Two low molecular weight analogues of polymers were also prepared and their properties compared with those of polymers of similar structure. The two model compounds form stable smectic mesophases over a wide range of temperatures, which shows the high mesomorphogenic ability of both mesogenic units.     

New magnetic properties of macromolecular compounds containing conjugated double bonds

Summary It has been shown that macromolecular compounds possessing conjugated double bonds reveal new magnetic properties. In the first place, the presence of a sufficiently developed system of conjugate double bonds produces the phenomenon of unpairedness in the basic state of the system, which is manifested in pure spin paramagnetism. It may be suggested that this effect occurs for all molecules possessing conjugated double bonds, but may only be observed experimentally with the experimental techniques at present available for sufficiently large molecules. In the second place, the macromolecular systems which have been studied are characterized by properties closely similar to the antiferromagnetic properties revealed by substances with incompletely compensated antiferromagnetic interaction. This effect depends essentially on a regularized structure within the organization of all the specimens. The authors believe that further investigation involving the synthesis of polymers of this class may lead to the creation of polymeric materials with magnetic properties which, not only qualitatively but also quantitatively, will approximate to the magnetic properties of the ferrites.Translated from Zhurnal Strukturnoi Khimii, Vol. 1, No. 1, pp. 103–108, May–June, 1960     

Resonance in compounds with multiple conjugated bonds

The resonance of the compounds buta-1,3-diyne (1), buta-1,3-diene (2), hexa-1,3,5-triyne (3), hexa-1,3,5-triene (4), hexa-3-en-1,5-diyne (5), and hexa-1,5-dien-3-yne (6) was analyzed. The molecular geometry, π molecular orbitals, and the electron density of these compounds were analyzed. The NBO, AIM, and NRT methods were used. By comparing the electronic structures of compounds 1 and 2 and by considering that the latter is a classic example of a π-conjugated compound (Org Lett 5:2373–2375, 2003; Org Lett 5:2373–2375, 2004), it was possible to conclude that the conjugation of compound 1 is larger than that of 2. Compounds 3 and 4 were also studied, in order to understand the effect of a longer conjugated chain, and it was found that the resonance also increases in the case of 3. In addition, the effect of changing the order of the central bond was investigated by comparison of compounds 5 and 6 with 3 and 4, respectively. The results indicated that changes produce small alterations in the properties of compounds 3 and 4.     

锂在共轭双键高分子中的电化学嵌入反应3: 锂在聚萘中的电 化学嵌入反应

研究了锂在导电高聚物---聚萘中的嵌入反应。聚萘样品经650℃处理,作为锂电池的正极,组装成Li/(C~1~0H~6)~n电池。X射线衍射分析、ESR实验、X射线光电子能谱分析等一系列实验证实上述电池的正板反应是锂在聚萘中的电化学嵌入反应。通过XPS实验对嵌入聚萘的锂进行了价态分析,认为嵌进去的锂是以原子态及离子态两种状态存在,其结合能分别为55.7eV和57.4eV。采用电化学暂态测量技术研究了锂在导电高聚物---聚萘中的扩散,计算了锂在嵌合物中的离子电导率及淌度。用Hebb-Wagner直流极化法测量了嵌合物的电子电导。     

Electronic structure of long molecules with conjugated bonds

The -electron system in a long molecule of the polyene type was calculated according to the Hartree-Fock self-consistent field method in which electrons with different spins are located on different molecular orbitals. The ground state of the -electron system in a long molecule is found to be antiferromagnetic and possesses a gap in the one-particle excitation spectrum. The calculated value of the first -electron transition as a function of the number of atoms in the polyene chain is in good agreement with experiment.     

Photoinitiators with double and triple bonds

In continuation of our research on new chromophores for photoinitiators (PIs) we investigated a series of double and triple bond containing PIs based on benzophenone (BP), thioxanthone, benzil (BZ), benzildimethylketal (BDK), and hydroxyalkylphenone. UV‐Vis spectroscopy revealed an absorption shifted up to 50 nm to the visible range of the spectrum. With steady state photolysis experiments, the rates of decomposition (R_d) were determined. Compared to the commercially available reference PIs the R_d of the new PIs were nearly identical. By quenching reactions with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO), α‐cleavage was identified for Type I initiators. Generally, all new compounds are suitable as PI especially for longer wavelengths. Nevertheless it has to be noted that the PI concentration has to be selected carefully to achieve optimum reactivity. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 289–301, 2008     

Synthesis of polyesters containing acetylenic bonds in the chain

Summary By joint oxidative dehydropolycondensation of p-diethynylbenzene and dipropargyl esters, polymers have been obtained that contain triple bonds alternating with ester groups.     

Interaction of polyesters with epoxy polymers: Insertion of oxirane rings into ester bonds

Epoxy oligomers readily interact (hardening) with polyesters of different structures (heterochain, carbochain, aliphatic, aromatic), as indicated by the change of properties and infrared spectra of an epoxy polymer–polyester composition on heating. The curing is caused by the reaction of the oxirane ring with ester groups and proceeds by the mechanism of “insertion” of the fragment of the oxirane cycle into the ester bond without scission of the molecular chain of polyesters. This mechanism of interaction is confirmed by study of a model reaction of phenyl benzoate with phenylglycide ether to lead to the formation of 1,3-diphenyl ether of 2-benzoyl glycerine. The latter was also produced by another way. The reaction of polyarylate with phenylglycide ether confirmed also that interaction of the ester group with the oxirane ring proceeds by the mechanism of “insertion.” This interaction proceeds with a high conversion and without rupture of the macromolecules (molecular weight does not decrease). The reaction of the oxirane ring with the ester group is accelerated in the presence of sodium salts of carboxylic acids, carbonic acid, and sodium phenolates.     

Reactions of diazomethane with sulfonyl-activated double bonds

The cyclo-addition reaction of diazomethane with α,β-unsaturated sulfones is described. Divinyl sulfone and phenyl vinyl sulfone give 1- or 2-pyrazolines depending on the reaction conditions. cis- and trans-1,2-Bis(methylsulfonyl)ethene form pyrazolines, which on reaction with either triethylamine or excess of diazomethane lead to substituted pyrazoles.     

Photocrosslinkable polymers having p-phenylenediacrylate group in the side chain: Argon laser photoresist

Preparative methods and photosensitivity characteristics of polymers bearing the p-phenylene-diacrylate (PDA) group are described. Condensation of a copolymer of methyl methacrylate and glycidyl methacrylate with p-phenylenediacrylic acid monoester gave highly photosensitive polymers. An alternative method to introduce PDA group is the substitution of chloromethyl-styrene polymer with p-phenylenediacrylic acid monoester monoalkali salt. The latter method was found to be more favorable for preparing soluble photosensitive polymers. The polymers thus prepared showed high sensitivity to light of 488 nm from an Argon laser when sensitizers are used, and the photocrosslinking quantum efficiency was 0.44. Preliminary results on holographic recording with this polymer is also mentioned.