End Group Functionality of 95-99%: Epoxide Functionalization of Polystyryl-Lithium Evaluated via Solvent Gradient
Philip Dreier1, Junyoung Ahn2, Taihyun Chang2
1Department of Chemistry, Johannes Gutenberg University Mainz, 55099, Mainz, Germany.
Macromolecular Rapid Communications
|August 9, 2022
Summary
Anionic polymerization achieves high end-capping efficiency (>95%) for functional polymers using epoxides. This method yields polymers with controlled molar mass and dispersity, demonstrating exceptional terminal functionalization.
Area of Science:
- Polymer Chemistry
- Organic Synthesis
- Analytical Chemistry
Background:
- End group functionality is critical for designing functional polymers.
- Anionic polymerization offers precise control over polymer architecture.
- Epoxides are versatile reagents for introducing end-group functionality.
Purpose of the Study:
- To investigate the end-capping efficiency of living polystyryl lithium with various epoxides.
- To synthesize hydroxy-functional polystyrene with controlled molar mass and low dispersity.
- To evaluate the deprotection and esterification of functionalized polystyrene chains.
Main Methods:
- Living anionic polymerization of styrene.
- End-capping with ethylene oxide, ethoxy ethyl glycidyl ether, and isopropylidene glyceryl glycidyl ether.
- Solvent Gradient Interaction Chromatography (SGIC) for analysis of end-capping efficiency, deprotection, and esterification.
- Characterization of molar mass and dispersity.
Main Results:
- End-capping efficiencies generally exceeded 95% for all epoxides studied.
- Hydroxy-functional polystyrene (PS-OH) with molar masses of 13.8-15.0 kg/mol and dispersities of 1.05-1.06 were obtained.
- Nearly quantitative deprotection (>99%) of acetal and ketal groups yielded multihydroxy functional polystyrene.
- Esterification of PS-OH with succinic anhydride showed 98% conversion.
- SGIC demonstrated high terminal functionality (95-99%) and revealed elution orders based on end-group polarity.
Conclusions:
- Anionic polymerization provides exceptionally high terminal functionalization efficiency for polymer chains.
- SGIC is a powerful analytical tool for characterizing end-group functionality and side reactions.
- The studied epoxides are effective for synthesizing well-defined functional polystyrene with high end-group fidelity.
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