Siklohekzenoksit'in katyonik polimerizasyonunda tetrametil tiouramdisülfit'in etkisi
Effect of tetramethylthiuramdisulfide on the cationic polymerization of cyclohexeneoxide
- Tez No: 66798
- Danışmanlar: DOÇ. DR. METİN H. ACAR
- Tez Türü: Yüksek Lisans
- Konular: Kimya, Chemistry
- Anahtar Kelimeler: Polimerleşme, Siklohekzanoksit, Tetrametiltiouramdisülfit, Polymerization, Cyclohexane oxide, Tetramethylthiuramdisulfine
- Yıl: 1997
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Kimya Ana Bilim Dalı
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: Belirtilmemiş.
Özet
ÖZET Bu çalışmada, radikal kaynağı ve elektron transfer bileşiği kullanılarak katyonik ısısal polimerizasyonla fonksiyonel uç gruplu (telechilic) polimer ve bu polimerden de initer sistemle (radikalik polimerizasyon) blok kopolimer sentez edilmiştir. Bu amaçla, radikal kaynağı olarak tetrametiltiouramdisülfit (TMTD) ve elektron transfer bileşiği olarak N-etoksi-2-metil-piridinyum hegzafloro fosfat (EMP) kullamlarak siklohekzenoksit'in (CHO) katyonik polimerizasyonu gerçekleştirilmiştir. Elde edilen polimerin (T-PCHO) tiouram uç grubunun initer özelliğinden faydalanılarak, radikalik polimerleşen bir monomer olan metilmetakrilat varlığında fotokimyasal olarak blok kopolimer sentezi gerçekleştirilmiştir. T-PCHO ve blok kopolimerler ER, UV, GPC kullanılarak karakterize edilmiştir. T-PCHO varlığında MMA'tan fotokimyasal yolla elde edilen polimerlerin, dönüşüm ile molekül ağırlıklarının lineer değişimi, tiouram gubunun varlığını ve initer özellik gösterdiğini kanıtlamaktadır. O s s ^^ ^/ a Me2-N-^-S-S-C-N-Me2 + (Ql *? Me^-N-^-S Ş PF6 l + 6 OEt S ^wwwwwwiwwuw» ^ l^S^ - M - O- S. +. *********************** MMA ~B?_N_£_S. +. Blok kopolimer iv
Özet (Çeviri)
SUMMARY There have been several classical methods for the preparation of block copolymer which generally involve the successive polymerization of two ör more monomers by the same mechanism. Transformation reactions extend the range of possible monomer combinations in block copolymer. This approach allows to be terminally functionalized by groups capable of initiating a different mode of polymerization The iniferter method, for the preparation of block copolymers, has been extensively explored during the last decade, primarly by Otsu et al. in this concept, iniferters (initiator - transfer agent -terminator) were used to design the structure of polymer chain ends in radical polymerization. Several organic disulfides and phenyl azotriphenylmethane were found to serve asphoto and thermal iniferters,respectively. Polymers obtained by using iniferters,still have iniferter function capable of initiating the polymerization of another monomer yielding block copolymers. İniter (initiator-terminator) compounds have the ability to initiate the polymerization and take part termination reactions. The cationic polymerization of cyclohexeneoxide was studied in the presence of tetramethylthiuram disulfide (TMTD) and N-etoxy-2-methyl-pyridine hexaflouro phosphate (EMP) as radical source and electron transfer agent, respectively. The polymers obtained this way shovved initer functionality as was evidenced by block copolymerization reactions according to the following reaction. O 5S^<^^S Me2-N-C-S-S-C-N-Me2 +(O^*. Me2-N-C-S ~~«»~»»~*~»*~>»~» PFe l+t 6 OEt î MMAu»^^^^“MMAMer-N-C-5 - +. ~*~*~~~~~«~~«~»~ Block copolymer vThe polymerization of CHO was carried out in the presence of TMTD and EMP. Poly cyclohexeneoxide with thiuram end groups (T-PCHO) was used to initiate the radical photo polymerization of methylmethacrylate (MMA) via initer (initiator-transfer) mechanism. The UV spectrum of T-PCHO possesses an absorbtion band at around X=278 nm region (figure 1) indication attachement of thiuram end groups + 1.09A 0.200 < A/DIU + 0.00A 200.0 50.0<NM/DIU. ) NM 400.0 Figure l.a- UV VIS spectrum of methyldiethyldithiocarbamate in CH2C12 (8.65x10.5 M) b- UV VIS spectrum of T-PCHO in CH2C12 ( 0.5 g./ 1). The plots of %conversion change against the reaction time (RT),and molecular weight (Mw) change against the RT, and the Mw change of polymers ( AMn = Mrii - Mno ) against the conversation is shown in figure 2, figure 3 and figure 4 respectively. Here, Mn! and Mno denote Mw of the polymer recorded after various polymerization times respectively. VI0s- TîrrErtri Figure 2. Conversion versus the reaction time of polymerization of MMA with T-PCHO ( MMA: 2 ml, T-PCHO: 0.2 g., CH2C12 ) Ttrrefrrt Figure 3. Molecular weight versus the reaction time of polymerization of MMA with T-PCHO ( MMA: 2 ml, T-PCHO: 0.2 g., CH2C12 ) vuGonveisicn% Figure 4. Molecular weight versus the conversion of polymerization of MMA with T-PCHO ( MMA: 2 ml, T-PCHO: 0.2 g., CH2C12 ) As can be seen, Mn of the polymers increased linearly with conversion, which indicates that this polymerization proceeds via a quaisa-living radical mechanism in a manner propoced by Otsu et al. Figure 5. shows the GPC traces recorded with polymer isolated at various reaction times in polymerization of MMA with T-PCHO. The GPC trace of T-PCHO showed unimodal molecular weight distribution, that is a new peak due to higher molecular weight side with time. İn relation to this, the peak for lower molecular weight polymer decreased and that of higher molecular weight polymer increased. IR spectra of T-PCHO, crude polymer of T-PCHO initiated PMMA and block fraction of T-PCHO initiated PMMA were illustrated in figure 6, figure 7 and figure 8. VUl50.00- 45.00-^ 40.41 35.00- 30.00-^ 25.00^ |20.00-: 15.00-^ 10.00-^ 5.00 0.00 - -5.00-^ n ' T”5.00 10.00 Figure 5. GPC traces for MMA polymerization with T-PCHO at various reaction times. IXı J...a.s _c U o O ON 6 IS CD ' CD O X u x CD CU I. CD CD CO CO CD T CD 10 CO 1 o 6 X <0 Q H 1- _l O u Pu o NO 2P-T - If) O If) © © © 'S' O Ol K U _c an es ö II O u o- I H“B II < S 2 <f Oh T3 O U o- ı © © © 03 E _>> ”S o. 3 ı- O <*- O S o © 0£ r- s- 3 2P xı"T.3 00.... er. >3 -T© h -t IV. B OJ in fe XII
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