Reactive polymers bearing styrene pendants through selective anionic polymerization of 4-vinylbenzyl methacrylate
Title | Reactive polymers bearing styrene pendants through selective anionic polymerization of 4-vinylbenzyl methacrylate |
Publication Type | Journal Article |
Year of Publication | 2012 |
Authors | Y. Mohan, M, Raghunadh, V, Sivaram, S, Baskaran, D |
Journal | Macromolecules |
Volume | 45 |
Issue | 8 |
Pagination | 3387-3393 |
Date Published | APR |
ISSN | 0024-9297 |
Abstract | Selective anionic polymerization of 4-vinylbenzyl methacrylate at methacrylate site has been achieved using resonance stabilized anionic initiators such as 1,1-diphenylhexyllithium (DPHLi) and tritylpotassium (TritylK) in tetrahydrofuran (THF) at -78 degrees C. Polymerization proceeded selectively through methacrylate functionality of the monomer in a controlled manner and produced polymers and copolymers with narrow molecular weight distribution at low temperatures (<=-40 degrees C). H-1 NMR of the polymer showed the presence of styrene pendants in every monomeric repeating unit. The polymerization results confirm that the resonance stabilized carbanions with an optimum pK(a) (30 <= pK(a) <= 32) of their conjugate acids such as DPHLi and TritylK do not react with styrene functionality at 78 degrees C. The selective initiation without cross-linking is attributed to the differences in the electronegativity between polar methacrylate and styrene functionalities and an attenuation of initiator reactivity at low temperature. Poly(4-vinylbenzyl methacrylate) and its copolymers with the vinyl pendant in close proximity with ester linkage are very reactive and unstable, readily undergoing cross-linking in solution or in solid state with or without a radical initiator. |
DOI | 10.1021/ma202750b |
Type of Journal (Indian or Foreign) | Foreign |
Impact Factor (IF) | 5.521 |