Title page for ETD etd-05252009-021808


Type of Document Master's Thesis
Author Li, Yi
URN etd-05252009-021808
Title Studies Related to the Alternating Copolymerization of Substituted Stilbenes
Degree Master of Science
Department Chemistry
Advisory Committee
Advisor Name Title
Turner, S. Richard Committee Chair
Davis, Richey M. Committee Member
Long, Timothy E. Committee Member
Marand, Herv L. Committee Member
Riffle, Judy S. Committee Member
Keywords
  • Polyelectrolytes
  • Homopolymerization
  • Alternating Copolymerization
  • N-Phenyl substituted Maleimides
  • Substituted Stilbenes
Date of Defense 2009-05-07
Availability unrestricted
Abstract
Stilbene containing polymers are a group of interesting and versatile polymers. The pendent phenyl ring along the polymer backbone can impart unusual rigidity to the polymer backbone due to steric repulsion. By functionalizing stilbene, a variety of functional groups and ionic groups can be precisely placed along the polymer chain with tunable charge density. Therefore, stilbene containing polymers are potentially rod-like polyelectrolytes with controllable charges and charge density. They are the basis of a novel group of rigid synthetic polyelectrolytes and can be used for furthering our knowledge of rigid polyelectrolytes.

A novel series of methyl substituted stilbenes were synthesized and copolymerized with maleic anhydride. A conversion-time study was undertaken to understand the methyl substituent effect on copolymerization rates. Methyl substituted stilbene-maleic anhydride copolymer compositions were determined by quantitative 13C 1D NMR. SEC measurements showed the weight average molecular weights of these copolymers vary from 3 000 to over 1 000 000 g/mol. No glass transition temperature or crystalline melting temperature was observed between 0 oC and 250 oC by DSC. TGA showed that these polymers have 5% weight loss around 290 oC.

Precursors to a polycation and a polyanion based on functionalized stilbenes and maleimides have been prepared: poly(di-t-butyl-(E)-4,4’-stilbenedicarboxylate-co- N-(4-(t-butoxycarbonyl)phenyl)maleimide) and poly(N,N,N’,N’-tetraalkyl-4,4’-di- aminostilbenes-co-N-4-(N’,N’-dimethylaminophenyl)-maleimide). These copolymer precursors were characterized by 1H NMR, SEC, TGA, and DSC. The 1H NMR spectrum indicated the rigidity of copolymer backbones. SEC measurements showed the weight average molecular weights of these copolymers vary from 5 000 to 11 700 g/mol. No glass transition temperature or crystalline melting temperature was observed between 0 oC and 175 oC by DSC for poly(di-t-butyl-(E)-4,4’-stilbenedicarboxylate-co-N-(4-(t-butoxy- carbonyl)phenyl)maleimide). TGA showed that this polymer has 5% weight loss around 210 oC and 26% weight loss on the first stage of decomposition which corresponds to elimination of t-butyl functional group in the copolymer.

The homopolymerization of EMS-III via free radical polymerization, anionic polymerization and cationic polymerization was attempted. However, no polymer was obtained from any of these polymerization methods. In anionic polymerization, the solution changed to red upon the addition of the initiator sec-bu-Li, indicating the successful addition of the sec-bu-Li to EMS-III. However, the initiated monomer did not propagate to form homopolymer.

Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  Yili_ThesisFinal1.pdf 1.35 Mb 00:06:15 00:03:13 00:02:49 00:01:24 00:00:07

Browse All Available ETDs by ( Author | Department )

dla home
etds imagebase journals news ereserve special collections
virgnia tech home contact dla university libraries

If you have questions or technical problems, please Contact DLA.