Bis (allil) amidlere etanditiyol katılma reaksiyonu ile yeni tiyoeteramid polimerlerinin elde edilmesi

Abstract

Bu araştırma çalışmasında oksalik asit, malonik asit ve tereftal asidin N, N' diallil amidleri sentezlenmiş ve bu yeni monomerlerin etanditiyolle katılma polimerleşmeleri incelenmiştir. Kinetik incelemeler 8 saatlik reaksiyon süreleri sonunda molekül ağırlıkları Mn 2000-4000 arasında olan polimerlerin elde edilebildiğini göstermiştir. Ele geçen yeni polimerler poliamidlerin kristal özelliği ile tiyoeterlerin amorf özelliğini biraraya getirmiştir. Oluşan polimerlerde kristal özelliğinin yine yüksek oranlarda var olduğu ancak erime sıcaklıklarının azaldığı görülmüştür. Bu da tiyoeterlerin yapıya girmesiyle poliamidlerin işlenme (proses) sıcaklıklarının azaltabildiğini ortaya koymaktadır.

Poly ( bis ether amide ) 's via addition of ethanedithiol to bis (aiiyl) amides Allyl monomers are difficult to polymerize by radical initiators. Because initiation step involves two competitive fundamental reactions, addition to vinyl group and hydrogen abstraction from allylic carbon which is adjacent to the double bond. R-CH2 -CH - CH2 -X R' + CH2 = CH - CH2 -X " (1) R - H + CH2 = CH - X In general the allyl radical formed in the addition reaction is very reactive and it is capable of increasing kinetic chain length of the reaction by another addition reaction. In contrast, allylic radical formed in the abstraction reaction is stable due to resonance. CH2 = CH - CH - X-- CH2 - CH = CH - X (2) For this reason allylic radical too unreactive to interact with another allyl monomer, Instead, it will often undergo combination reactions with other radicals. The second radical will most probably be either the radical derived from the initator or another allyl monomer, This fact is known as so called "degradative chain transfer". In most cases the rates of the two reactions are almost equal and therefore average degree of polymerization of allyl monomers is between 4-14. Hence, allyl polymerization gives low-molecular weight polymers. On the other hand, diallyl monomers in which two allyl groupsattached to the same carbon or nitrogen atom undergo cylopolymerization yielding non-crosslinked polymer of (Degree of polymerization, DP) between 25-50. One of the first diallyl monomers of this type to be investigated was diethyl-diallylammonium hydroxide. This monomer polymerizes radically to yield water-soluble polymer containing five membered repeating units. Vl \ / CoH 2n5 XOH' C9H 2n5 Radikal polimeıleşme (3) Similarly, diallyl diethyl malonate and N,N-diallyl cynamide monomers also undergo cyclo-polymerization. Recently our research group has prepared tetraallyl piperazinium dichloride by Hoffmann alkylation of piperazine with allylchloride. The resulting product has been demonstrated to be an efficient crosslinker for water soluble polymers such as polyacrylic acid and polyacrylamide. ^ / CH2 I CI HN NH (4) Being water soluble and non-hydrolysable the crosslinker is expected to find a wide variety of applications in gel electrophoresis etc. There are few diallyl monomers found industrial applications. These are diallyl phtalate and ethylenegiycoldiallyl dicarbonate which give crosslinked polymers having some cyclic structures. Another important class of allyl polymerization is the step-growth polymerization reaction involving addition of a thiol to the double bond. The first report of this type of polymerization was self polymerization of 2 - propene-1- thiol reported in 1926. CH2-CH-CH2"SH C H2-C H2-C H2-0 -Ti or CH3 I 1 CH-CH2-S - J n (5) Since then, many polymers have been prepared based on this principle. But most prominent study in obtaining high molecular weight polymer was first succeded by Marvel. He has succeded to obtain high molecular weights as high as 60.000 by radical-catalysed addition of 1,6 hexanedithiol to 1,5 hexadiene. VII The structure of this polymer is expected to be an anti-Markownikoff addition- product. These polymers have been considered as rubber-like non crystalline polymers. In the present study, we have, first time, described polyamide thioethers derived from diallylamides and ethanedithiol. The main goal of this study is to investigate polymerizability of diallylamides with ethanedithiol and the behavior of the polymers combining the crystalline character of amides and amorph character of the thioethers. For this purpose, N.N'-Diallyl oxalamide, N.N'-Diallyl malonamide and N.N'-Diallylterephtalamide monomers have been prepared by aminolysis of the corresponding esters with ally! amine, as outlined in the following scheme. 00 C2H5-0-C-C-0-C2H5 + 2 H2N-CH2-CH=CH2 00 C H2=C H-C H2-NH-C-C-NH-C H2-C H=C H2 O O C2H5-0-C-CH2-C-0-C2H5 + 2 H2N-CH2-CH=Cri O O C H2=C H-G H2-NH-C-C H2-C-NH-C H2-C H=C H2 C-O-CHrCHrO- + 2 H2N-CH2-CH=CH2 n PET CH2=CH-CH2-NH-G C-NH-CH2-CH=CH2 (6) viii The structure of these monomers have been elucidated by elemantary microanalysis, 'H-NMR and IR spectroscopic techniques. Polymerizability of these allyl monomers by addition of ethanedithiol investigated. Addition of ethanedithiol in dioxane solution is resonably fast and polymerization is completed in about ffch The resulting polymers are insoluble in common organic solvents and soluble m-cresoi / Dimetilsulfoxide (1/1, v/v) mixtures. Polymerizations have also been carried out in presence of dibenzoyl peroxide as catalyst for anti-Markownikoff addition. Kinetics of polymerizations have also been studied and the effect of illumination has been investigated. o 0 C H2=C H-C H2-NH-C-R-C-NH-C H2-CH=CH2. HS-CH-rCH^SH o 0 ~[-S-CH2-CH2-S-CH2-CH2-CH2-NH-C-R-C-NH-CH2-CH2-CH2-]- O O -fs-CH2-CH2-S-CH-CH2-NH-C-R-C-NH-CH2-CH^- L I I Jn CH3 CH3 (7) An interesting aspect of these polymers is that, crystalline behavior of amides and noncrystalline behavior of polysulfides are being combined in these polymers. We have investigated their crystallinities and thermal behaviors by DSC and TGA. Thermal analysis results indicate that, polymers obtained under irradiation show lower melting temperatures than those of the direct addition polymers. This is because of destructive effect of light. Generaly polymer melting temperatures increase with increasing molecular weight. The phenomenon has been established by the melting points of the samples in kinetic measurements. While the glass transitions were not detectable on DSC termograms of polymers. The resultant polymer exhibited melting and decompositions temperatures, interestingly. The decomposition temperature of the polymer obtained after 20 h reaction was significantly higher than that of the one obtained after 8h. This increase may be attributed to the interaction of thiyl radicals with the already formed chains, i.e. branching and crosslinking since, probability of the reaction on end groups diminished as the chains grow. This was further evidenced by the inspection of the IR spectra of related polymers. At present it is not possible to confirm the exact nature of polymers obtained under in presence UV. light. Conversion-time plots (Fig.DI) of solution polymerization indicate that, polymerizations obey second order kinetics, similar to many bimolecular condensation polymerizations. An interesting aspect of the polimerizations is that, IX the effect of irradiation on polymerization result in decreasing the yields, for long term of periods. In those cases, conversion- time plots pass through a maximum. Where a inital concentrations of the monomers, l0 radiaton density of UV. light under irradition, k rate constant for polymerization and k' rate constant of depolymerization reaction. On the other hand the effect of peroxide catalyst is dramatic. At the begining under illumination, peroxide catalyst accelerates the polymerization. Convertion curves rise to a maximum than reduces sharply to lower yields. Hence, the effect of U.V. light is not only the acceleration but also depolymerization. These two effects are competitive. At higher convertions the accelaration becomes much favour to depolymerization. So kinetic equation of polymer formation can be written as, dx - =k(a-x)2-k'l0x (8) dt However, it is difficult to predict if this is a depolymerization or decomposition. Most probably the effect of UV. light cause to homolytic chain scission yielding diradicals. Thereafter these radicals attact on preformed polymers and result in formation of new combination products by hydrogen abstraction. Indeed, comparision of the IR spectra of polymer formed at the begining with those of the one obtained after 20h indicates that these two product are not the same (FigA1,A2,A3). On the other hand X-ray difraction paterns exhibite high crystallinities for all polymers. There are small differences between the polymers obtained in the presence or absence of UV-light. The polymers obtained by direct interaction show somewhat higher crystallinities in comparision with the polymers obtained under illumination.