One-Step Approach to Polyester–Polyether Block Copolymers Using Highly Tunable Bicomponent Catalyst

Abstract

Phthalic anhydride and propylene/ethylene oxide are copolymerized at room temperature by a bicomponent metal-free catalyst comprising a mild phosphazene base and triethylborane. Provided with proper loadings of the two catalytic components, block copolymers with strict (AB) n B m type sequence structures and controlled molar mass (up to 60 kg mol −1 ) can be generated in one synthetic step, and the block architecture can be enriched by the use of mono-, di-, or tetrahydroxy initiators. The obtained polyester−polyether block copolymers readily undergo microphase-separation in bulk and nanoaggregation in selective (aqueous and alcoholic) solvents.

Phosphazene/Lewis Acids as Highly Efficient Cooperative Catalyst for Synthesis of High‐Molecular‐Weight Polyesters by Ring‐Opening Alternating Copolymerization of Epoxide and Anhydride

“…Similar results were also observed by Zhang and coworkers using triethylborane (TEB)/quaternary onium salts Lewis pair as catalyst for ROAC of propylene oxide (PO) and maleic anhydride . Recently, Zhao and coworkers reported the one‐step synthesis of polyester–polyether block copolymers by ROAC of PA and PO/EO using a mild phosphazene base with TEB . Chakraborty and coworkers systematically tested various Lewis acids, such as TEB, Al(CH 3 ) 3 , Et 2 Zn, and n ‐Bu 2 Mg, in combination with various Lewis bases, such as PPNCl, 4‐( N,N ‐dimethylamino)pyridine, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene, and TBD, as Lewis pair catalysts for ROAC of anhydrides and epoxides .…”

“…17 Recently, Zhao and coworkers reported the one-step synthesis of polyester-polyether block copolymers by ROAC of PA and PO/EO using a mild phosphazene base with TEB. 18 Chakraborty and coworkers systematically tested various Lewis acids, such as TEB, Al(CH 3 ) 3 , Et 2 Zn, and n-Bu 2 Mg, in combination with various Lewis bases, such as PPNCl, 4-(N,Ndimethylamino)pyridine, 1,8-diazabicyclo [5.4.0]undec-7-ene, and TBD, as Lewis pair catalysts for ROAC of anhydrides and epoxides. 19 It was found that the TEB/PPNCl pair stood out as the most active and effective one for the perfectly alternating and regionselective controlled ROAC of various epoxides with anhydrides.…”

An Investigation of the Organoborane/Lewis Base Pairs on the Copolymerization of Propylene Oxide with Succinic Anhydride

“…We therefore performed the PO/SA copolymerization with the TEB/t-BuP1 molar ratio of 1/1 at 30 °C with prolonged time (84 h, entry 2, Table 2), the conversion of SA was up to 98%, and Mn of the resultant poly(propylene succinate) was high (20.4 kg/mol) ( Figure S2), which is close to the calculated value (31.0 kg/mol). The catalytic mechanism of the LA/LB pair for the copolymerization of epoxide and anhydride has been investigated [26,27,41,42]. For the PO/SA copolymerization, the LB/OB pair firstly reacts with SA, which was determined by MALDI-TOF-MS spectrum (Figure 2).…”

“…When excess OB used, OB not only coordinates with the growing carboxylate (or alkoxide) anions for stabilizing them, but also activates PO (Scheme 3b). Therefore, excess OB addition often leads to the contaminant ether The catalytic mechanism of the LA/LB pair for the copolymerization of epoxide and anhydride has been investigated [26,27,41,42]. For the PO/SA copolymerization, the LB/OB pair firstly reacts with SA, which was determined by MALDI-TOF-MS spectrum (Figure 2).…”

Copolymerize Conventional Vinyl Monomers to Degradable and Water‐Soluble Copolymers with a Fluorescence Property

“…In addition to these two methods, other polymeric methodologies, such as radical ROP of cyclic ketene acetals and copolymerization of epoxide/anhydride, have been developed for the preparation of polyesters. [ 18–25 ] However, these methods often have a limited range owing to either the expense of the monomers or the harsh polymerization conditions. Clearly, a more feasible approach for degradable polymers is needed.…”