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Molecularly defined caprolactone oligomers and polymers: synthesis and characterization
Kenichi Takizawa1, Chuanbing Tang, Craig J Hawker
1Materials Research Laboratory and Department of Materials, University of California, Santa Barbara, California 93106, USA.
Journal of the American Chemical Society
|January 15, 2008
Summary
Researchers synthesized precisely defined epsilon-caprolactone polymers up to the 64-mer using an efficient exponential growth strategy. This method yields well-characterized polymers, revealing a clear link between molecular structure and physical properties.
Area of Science:
- Polymer Chemistry
- Materials Science
Background:
- Controlled synthesis of polymers with defined molecular weights is crucial for understanding structure-property relationships.
- Epsilon-caprolactone polymers are widely used, but precise control over oligomer/polymer length has been challenging.
Purpose of the Study:
- To develop a scalable synthesis for molecularly defined epsilon-caprolactone oligomers and polymers.
- To investigate the structure-property relationships of these precisely defined macromolecules.
Main Methods:
- Utilized an exponential growth strategy with orthogonal protecting groups (TBDMS ether and Bn ester).
- Employed 1,3-dicyclohexylcarbodiimide (DCC) for efficient coupling reactions.
- Characterized synthesized materials using mass spectrometry, SEC, IR, NMR, TGA, DSC, AFM, and SAXS.
Main Results:
- Successfully synthesized monodisperse epsilon-caprolactone oligomers and polymers up to the 64-mer in gram quantities.
- Achieved high yields (>80-95%) in coupling reactions and quantitative yields in deprotection steps.
- Demonstrated a distinct structure-property relationship correlated with the number of repeat units.
Conclusions:
- The developed synthetic strategy allows for the precise control of epsilon-caprolactone polymer chain length.
- The study establishes a clear correlation between the molecular definition of oligomers/polymers and their physical properties.
- Observed significant differences in properties compared to the parent poly(caprolactone) polymer.
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