Block Copolymers of Macrolactones/Small Lactones by a "Catalyst-Switch" Organocatalytic Strategy. Thermal Properties and Phase Behavior
Abstract
Poly(macrolactones) (PMLs) can be considered as biodegradable alternatives of polyethylene; however, controlling the ring-opening polymerization (ROP) of macrolactone (ML) monomers remains a challenge due to their low ring strain. To overcome this problem, phosphazene (t-BuP_4), a strong superbase, has to be used as catalyst. Unfortunately, the one-pot sequential block copolymerization of MLs with small lactones (SLs) is impossible since the high basicity of t-BuP_4 promotes both intra- and intermolecular transesterification reactions, thus leading to random copolymers. By using ROP and the "catalyst-switch" strategy [benzyl alcohol, t-BuP_4/neutralization with diphenyl phosphate/(t-BuP_2)], we were able to synthesize different well-defined PML-b-PSL block copolymers (MLs: dodecalactone, ω-pentadecalactone, and ω-hexadecalactone; SLs: δ-valerolactone and ε-caprolactone). The thermal properties and the phase behavior of these block copolymers were studied by differential scanning calorimetry and X-ray diffraction spectroscopy. This study shows that the thermal properties and phase behavior of PMLs-b-PSLs are largely influenced by the PMLs block if PMLs components constitute the majority of the block copolymers.
Additional Information
© 2018 American Chemical Society. Received: January 22, 2018; Revised: March 2, 2018; Publication Date (Web): March 16, 2018. Research was supported by King Abdullah University of Science and Technology (KAUST). The authors declare no competing financial interest.Attached Files
Supplemental Material - ma8b00153_si_001.pdf
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Additional details
- Eprint ID
- 85351
- Resolver ID
- CaltechAUTHORS:20180316-160011662
- King Abdullah University of Science and Technology (KAUST)
- Created
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2018-03-26Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field