Sequence-Selective Terpolymerization from Monomer Mixtures Using a Simple Organocatalyst

Abstract

One-step synthesis of block copolymer from mixed monomers is of great interest and challenge. Using a simple non-nucleophilic organobase as the catalyst, we have achieved sequence-selective terpolymerization from a mixture of phthalic anhydride (PA), an epoxide, and rac-lactide (LA). Alcohol-initiated alternating copolymerization of PA and epoxide occurs first and exclusively because PA is substantially more active than LA for reacting with base-activated hydroxyl. When PA is fully consumed, LA polymerizes from the termini of the first block while excess epoxide stays intact because of the mild basicity of the catalyst. The two polymerizations thus occur tandemly, both in chemoselective manners, so that an aromatic–aliphatic block copolyester is generated in this one-step synthesis. The effectiveness and versatility of this approach is demonstrated by the use of ethylene oxide and several monosubstituted epoxides as well as mono-, di-, or tetrahydroxy initiators.

Studying the Ring-Opening Polymerization of 1,5-Dioxepan-2-one with Organocatalysts

“…Hedrick and coworkers have prepared polycarbonates, polylactides with excellent controlling and functionality using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the organocatalysts [17,18,19,20,21,22]. Zhao and Zhang’s group have developed a number of poly(ethylene oxide) based copolymers and polymerization methods with phosphazene catalysts [23,24,25,26]. Although organocatalysts have been widely studied for ROP, they have not been used as catalyst for ROP of cyclic 1,5-dioxepan-2-one (DXO) as far as we know.…”

Zinc Amido-Oxazolinate Catalyzed Ring Opening Copolymerization and Terpolymerization of Maleic Anhydride and Epoxides

“…One common strategy for tuning the polymer properties such as glass transition temperature ( T g ) is to incorporate additional monomers to form block or random copolymers [ 51 , 52 , 53 , 54 ]. Given the versatility of the current zinc catalysts for various epoxides and anhydrides, we were interested to see if terpolymerization could be achieved and how it could affect the properties of the resulting terpolymers.…”

A One‐Pot Strategy to Synthesize Block Copolyesters from Monomer Mixtures Using a Hydroxy‐Functionized Ionic Liquid

“…The conversion of PA was determined by 1 H NMR spectroscopy; b) The conversion of LA was determined by 1 H NMR spectroscopy; c) The content of ether was determined by 1 H NMR spectroscopy; d) M n and PDI were determined by GPC analysis in THF calibrated with polystyrene standards. Based on the above experiments and reported works, [13,14] we proposed a self-switchable pathway to illustrate the chemoselective mechanism of one-pot polymerizations from mixed monomers by HEMIMB (Scheme 2). First, the ringopening of PO with HEMIMB can generate alkoxide species for the terpolymerization.…”

“…[13] Meanwhile, Zhao and co-workers also confirmed that t-BuP 1 catalyst is active to produce sequence-controlled polyesters in one-step synthesis from monomer mixtures of PA, LA, and epoxides. [14] Although phosphazene bases catalysts can be employed for the selective copolymerization, [15] it remains a great challenge for the rational design of organocatalysts to operate the metal-free process from mixed monomers for diverse block copolymers. [16] Ionic liquids (ILs) as organic molten salts have been widely investigated for green solvent and catalytic applications.…”