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| Content Provider | PubMed Central |
|---|---|
| Author | Matson, John B. Virgil, Scott C. Grubbs, Robert H. |
| Abstract | Poly(tert-butyl ester norbornene imide) homopolymers and poly(tert-butyl ester norbornene imide-b-N-methyl oxanorbornene imide) copolymers were prepared by pulsed-addition ring-opening metathesis polymerization (PA-ROMP). PA-ROMP is a unique polymerization method that employs a symmetrical cis-olefin chain transfer agent (CTA) to simultaneously cap a living polymer chain and regenerate the ROMP initiator with high fidelity. Unlike traditional ROMP with chain transfer, the CTA reacts only with the living chain end, resulting in narrowly dispersed products. The regenerated initiator can then initiate polymerization of a subsequent batch of monomer, allowing for multiple polymer chains with controlled molecular weight and low polydispersity to be generated from one metal initiator. Using the fast-initiating ruthenium metathesis catalyst (H2IMes)(Cl)2(pyr)2RuCHPh and cis-4-octene as a CTA, the capabilities of PA-ROMP were investigated with a Symyx robotic system, which allowed for increased control and precision of injection volumes. The results from a detailed study of the time required to carry out the end-capping/initiator-regeneration step were used to design several experiments in which PA-ROMP was performed from one to ten cycles. After determining the rate of catalyst death, a single, low polydispersity polymer was prepared by adjusting the amount of monomer injected in each cycle, maintaining a constant monomer/catalyst ratio. Additionally, PA-ROMP was used to prepare nearly perfect block copolymers by quickly injecting a second monomer at a specific time interval after the first monomer injection, such that chain transfer had not yet occurred. Polymers were characterized by gel permeation chromatography with multi-angle laser light scattering. |
| Related Links | http://dx.doi.org/10.1021/ja809081h |
| Ending Page | 3362 |
| Page Count | 8 |
| Starting Page | 3355 |
| File Format | |
| ISSN | 00027863 |
| e-ISSN | 15205126 |
| Journal | Journal of the American Chemical Society |
| Issue Number | 9 |
| Volume Number | 131 |
| Language | English |
| Publisher Date | 2009-03-11 |
| Access Restriction | Open |
| Subject Keyword | Colloid and Surface Chemistry Biochemistry Chemistry(all) Catalysis Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Chemistry Colloid and Surface Chemistry Biochemistry Catalysis |
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