The ring-opening copolymerization (ROCOP) of epoxides
with CO2 or cyclic anhydrides is a versatile route toward
synthesizing
a wide range of polycarbonate and polyester copolymers. ROCOP most
commonly uses binary catalyst systems comprising separate Lewis acid
and nucleophilic cocatalyst components. However, the dependence on
two discrete catalyst components leads to low activities at low loadings,
and binary catalyst systems are prone to numerous side reactions.
It was therefore proposed that covalently tethering the Lewis acid
catalyst and cocatalyst together would increase both catalyst activity
and selectivity in epoxide ROCOP. Since these initial efforts, many
multifunctional catalysts featuring covalently tethered cationic or
Lewis base cocatalyst(s) have been developed for epoxide ROCOP. This
review examines multifunctional catalysts that have been developed
for copolymerization of epoxides with CO2, cyclic anhydrides,
carbonyl sulfide (COS), and cyclic thioanhydrides. In particular,
we will assess how multifunctional catalysts’ mechanisms of
operations lead to improved activity and selectivity in ROCOP.
Reactions between 3,4-propylenedioxythiophenes (ProDOTs) and N-alkyl isatins under ambient conditions result in isomerically pure indophenine materials as confirmed by TLC and 1 H NMR analysis. The resulting low band gap materials exhibit favorable inter-and intramolecular interactions, high thermal stabilities, low energy electronic transitions, and amphoteric redox behavior.
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