Organofosfonik asit içeren vinil polimerler sentezi

Abstract

Bu çalışmanın ilk kısmında organofosfonik asit-Ce(IV) redoks sistemiyle çeşitli vinil monomerlerinin polimerleşmesi incelenmiştir. Organofosfonik asit bileşikleri olarak; aminotrimetilen fosfonik asit (ATMP), 1-hidroksi etiliden (1,1-difosfonik asit) (HEDP), dietilentriamin penta (metilen fosfonik asit) (DTPMPA), N,N-di(metilen fosfonik asit) etanol amin (DMPEA), siklik fosfonik asit esteri (CPA), N,N-di(metilen fosfonik asit) N-metil amin (DMPAMA), Dequest 2086 kullanılmıştır. Vinil monomeri olarak akrilonitril, vinil asetat, 2-akrilamido-2-metilpropan sülfonik asit (AMPS), stiren, akrilik asit, akrilamid, maleik anhidrit, itakonoik asit, sodyum vinil sülfonat kullanılmıştır. Stiren, vinil asetat, itakonoik asit ve sodyum vinil sülfonatla homopolimerleri elde edilememiştir. Elde edilen polimerlerin zincir uçlarında aminometilen fosfonik asit gruplarının bulunduğu görülmüştür. İkinci bölümde ise; zincir ucunda aminofosfonik asit grubu içeren molekül ağırlığı 10.000'den az olan poliakrilik asit sentezi gerçekleştirilmiştir. Bu amaçla 2- amino etantiol bileşiği kullanarak amin uç gruplu düşük molekül ağırlıklı poliakrilik asit elde edilmiş, daha sonra Mannich reaksiyonu uygulanarak amin uç grupları, amino di(metilen fosfonik asit)' e dönüştürülmüştür. Zincir transfer bileşiği olarak tioglikolik asit alınarak düşük molekül ağırlıklı poliakrilamid, değişik oranlardaki akrilamidle, akrilamid-akrilik asit kopolimerleri elde edilmiştir. Bu polimerlere Hofmann degradasyonu uygulanarak poli (akrilik asit-ko-vinil amin) polimerleri elde edilmiştir. Bu kopolimerlerin amin grupları; Mannich reaksiyonu ile amino di(metilen fosfonik asit) gruplarına dönüştürülmüştür. Bu şekilde sentezlenen; yan grupta ve uç grupta aminometilen fosfonik asit grubu içeren düşük molekül ağırlıklı poliakrilik asitler, endüstriyel olarak kazantaşı oluşumunun engellenmesinde ticari poliakrilik asit ile mukayese edilmiştir. Her iki tür poliakrilik asitin, ticari poliakrilik asitden 3- 4 kat daha etkin olduğu bulunmuştur. Çalışmanın son kısmında ise, aminometilen fosfonik asitler, Ce(III), ışık üçlü sistemiyle vinil monomerlerinin fotopolimerleşmesi çalışılmıştır. Burada ATMP-vinil asetat ve HEDP-akrilik asitle polimer elde edilememiştir. Monomere bağlı olarak kullanılan organofosfonik asit bileşiğinin uygun seçilmesinin gerektiği ortaya çıkmıştır. Ayrıca Ce(III) konsantrasyonu ve HEDP, ATMP konsantrasyonlarının molekül ağırlığına ve verime etkileri çalışılmıştır. Organofosfonik asit konsantrasyonu veya Ce(DI) konsantrasyonu arttıkça molekül ağırlığı düşmektedir.

Redox polymerization of vinyl monomers is one of the most used polymerization method in industry. The polymer produced with this method usually contains corresponding chain ends. For example, persulphate/Fe+2 and bisulphite redox system is used for polymerization of acrylonitrile/vinyl acetate and the product, poly(acrylonitrile-co- vinyl acetate) contains sulphonate/sulphate chain end which is necessary for succesful dying of fibre produced from these polymers. Redox system of Ce+4-organic reducing agent was recently used in our department for the preparation of block/graft copolymers. In this redox system polymer chain contains organic reducing agent chain ends. This method was used for the preparation of desired chain-ended vinyl polymers. The redox polymerization may be represented as follows; L: organic reducing agent. Ce+4 + L- H ? L" + Ce*3 + h + L' + n CH2=CHX »- L-(cH2-CH-)- In this work, Ce+4-organophosphonic acid system was used for polymerization of vinyl monomers in order to produce vinyl polymers with organophosphonic acid chain ends. The results are summarized in the Table 1. The proposed redox initiation and polymer formation can be described as follows: O

^OH CHjPOaH, /CH2_P\0H H\ /CH2\ I /*K /°H HPaPCHj-N +Ce(iv) =^: 0=P N P=0 ? Cr^-p^ O- Ce O II >3H Complex CH2P03H2 CH2P03H2 H<\ /CH2N | HQ XhU | O^p N- CH- PO,H,+ H+ nCH^CHX n±/ nn_ CH-f CI-U-CH^ O ce3 o Ce3 P03H2 n X vu Organophosphonic acid groups are expected to impart water absorption and inflammability to the polymers. As seen in the Table 1, a number of organophosphorous compounds acted as reducing agent and reasonable yields were obtained. This system was used for the polymerization and copolymerization of other monomers such as acrylic acids and acrylamide. The results are summarized in the Table 2. Table 1. Polymerization of acrylonitrile with the redox system of Ce(IV)- organophosphorous acids. [Acrylonitrile]: 0.67 mol/l, T: 20°C, t: 4 h. * Monomer was acrylic acid Water soluble polyacrylic with molecular weight of lower than 5000 is used industrially in the boilers for scale inhibition together with organophosphorous compounds such as ATMP. Polyacrylic acid with ATMP chain-ends may show a good scale inhibition effect. Ce+4-ATMP redox system was used for polymerization of acrylic acid in order to produce polyacrylic acid with ATMP chain ends. However, with this system the molecular weight of the polymer could not be reduced to 1 0.000 range. Low molecular weight polyacrylic acid was produced with radical initiators in the presence of chain transfer agents. The chain transfer agent was 2-amino mercaptoethanethiol. Resulting polyacrylic acid with molecular weight of 10.000 contained chain end of amine group which was transformed into amino di(methylene phosphonic acid) by applying Mannich reaction. vui .İs? Another approach is to produce the low molecular weight polyacrylic acid containing amino di(methylene) phosphonic acid from vinyl amine copolymers. This was achieved by Hofrnann transformation of polyacrylamide with low molecular weight polyacrylamide and poly(acrylamide-co-acrylic acid) into poly(acrylicacid-co-vinylamine). ^_ç^ch2^çh)- I c=o I NH, COOH NH2 COOH Mannich der.HCI ? CHjO, HgPO; Hpf +y COOH CH, P03H Amine groups of poly(acrylic acid-co-vinyl amine) were converted into amino di(methylene phosphonic acid). The results are summarized in Table 3. Table 3. Charachteristics of PAA and copolymers before and after Hofrnann and Mannich reaction. * The conversion of amide to amine was assumed to be about 50%. ** The conversion of amine to amino di(methylene) phosphonic acid was assumed to be about 100%. Low molecular weight polyacrylic acids containing amino(dimethylene phosphonic acid) groups as side groups or as chain ends were used for scale inhibition. The results are shown in the Table 4. The mentioned polymers showed better scale inhibition effect than commercial polymer and amino tri(methylene phosphonic acid) (ATMP). This results is very promising. XI Table 4. The scale inhibition effect of low molecular weight polyacrylic acid which contains amino di(methylene) phosphonic acid groups. A unique combination of Ce(HI), ATMP and light, initiated the polymerization of vinyl monomers. This work was extended by changing the time and the type of amino di(methylene) phosphonic acid and monomers. CH2=CH + organophosphonic +Ce (m) JÜiiîl | acid compounds X X Organophosphonic acids containing aminomethylene phosphonic acid groups were effective.Ih this system homopolymerization of vinyl acetate was not successful with ATMP. Molecular weight of polyacrylic acid could be controlled by the concentration of Ce(m) and organophosphorous compounds (Table 5 and 6). 1 -hydroxy ethylidene 1,1- diphosphonic acid (HEDP) was used as chain transfer compound to reduce molecular weight. xu Table 5. Photopolymerization in the presence of Ce(m) and the effect concentration of organophosphorous compounds on molecular weight and yield. [ Ce(HQ]: 20 ramoW, [Acrylic acid]: 0.66 mol//, T: 25°C, t: 4 h. * T=40°C Table 6.The effect of CeQS) salts on photopolymerization of acrylic acid.