mz8b00353_si_001.pdf (1.39 MB)
Stereoselective Ring-Opening Polymerization of rac-Lactide Using Organocatalytic Cyclic Trimeric Phosphazene Base
journal contribution
posted on 2018-05-16, 11:49 authored by Shaofeng Liu, Huaike Li, Na Zhao, Zhibo LiPhosphazene base
is an important organocatalyst in polymer chemistry
owing to its high activity and versatility. In this contribution,
we demonstrate that cyclic trimeric phosphazene base (CTPB) can catalyze stereoselective ring-opening polymerization (ROP)
of rac-lactide (rac-LA) to produce
isotactic stereoblock PLA (Pi up to 0.93).
The polymerizations are highly controlled, as evidenced by linear
relationship between molecular weights (MW) and monomer conversions
and the narrow dispersity (Đ = Mw/Mn) of the resulted polymers
with high fidelity of end groups. The investigations on polymerization
parameters show that the tacticity of produced PLA depends on the
polymerization temperatures and solvents, while the kinetic studies
reveal a faster rate for ROP of l-LA as compared to rac-LA under same conditions. Based on these results, the
chain end control mechanism is proposed to explain the production
of isotactic stereoblock PLA from rac-LA by an achiral
catalyst.
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chain end control mechanismracpolymerization temperaturesCTPBP ipolymer chemistryMWend groupsROPmonomer conversionsachiral catalystpolymerization parameters showcyclic trimeric phosphazene baseOrganocatalytic Cyclic Trimeric Phosphazene Base Phosphazene basecatalyze stereoselective ring-opening polymerizationStereoselective Ring-Opening Polymerizationisotactic stereoblock PLA
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