Selective Ring‐Opening Polymerization of Non‐Strained γ‐Butyrolactone Catalyzed by A Cyclic Trimeric Phosphazene Base

Abstract

An ew superbase,t he cyclic trimeric phosphazene base (CTPB), was prepared with high yield and purity.Int he presence of alcohol, the CTPB serves as ah ighly efficient organocatalyst for ring-opening polymerization of the "nonpolymerizable" g-butyrolactone to offer well-defined poly(gbutyrolactone) with high conversions (up to 98 %) at À60 8 8C. The produced polymers have high molecular weights (up to 22.9 kg mol À1 )and low polydispersity distributions (1.27-1.50). NMR analysis of initiation process and the structural analysis of resulting polymers by MALDI-TOF suggest am echanism involving an activating initiator which leads only to linear polymers with BnO/H chain ends.Scheme 1. Synthesis of acyclic trimeric phosphazene base.

Ring-opening (co)polymerization of γ-butyrolactone: a review

“…Scheme 5: t-BuP4/alcohol system as initiating species for ROP of γBL 19 Cyclic trimeric phosphazene base (CTPB, Scheme 6) was also proposed as an organocatalyst for ROP of γBL. 20 CTPB was said inactive in the absence of any alcohol whereas it serves as a Scheme 6: Cyclic trimeric phosphazene base (CTPB) for ROP/ROCP of γBL 20,25,26 CTPB/ureas binary organocatalysts were also studied for the ROP of γBL 25 . Using 1cyclohexyl-3-(4-methoxyphenyl) urea, a urea bearing unsymmetrical and electron-donating substituents (Scheme 7), PγBL contained linear and cyclic structures with ̅̅̅̅ up to 35 000 g/mol, four times higher than CTPB alone, was prepared.…”

“…Since a couple of years, there is a breakthrough in ROP of γBL, which can now be performed at low temperature (below the ceiling temperature (Tc)) and high monomer concentration, to yield high molar mass PγBL with linear or cyclic structures. [18][19][20][21][22][23][24] Ring-opening copolymerization (ROCP) of γBL and other lactones with high ring strain energy (or cyclic ether) is another pathway to avoid its "non-polymerizability" (Fig. 1).…”

Geminal Dimethyl Substitution Enables Controlled Polymerization of Penicillamine-Derived β-Thiolactones and Reversed Depolymerization

“…[13][14][15][16][17] Along this direction, many biomass and CO2 derived synthetic polymers, mainly polyesters and polycarbonates, have shown their capability of establishing a circular economy of monomer-polymer-monomer. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] Despite the advancement, the development of recyclable polymers under mild condition and at low energy cost have been limited.…”

Chemoselective Ring-Opening Polymerization of Bio-Renewable α-Methylene-γ-Butyrolactone via an Organophosphazene/urea Binary Synergistic Catalytic System Toward a Sustainable Polyester

“…6,7 One emerging frontier in chemical recylable polymers is the design and preparation of polyesters using lactones with five-membered ring as building blocks. [8][9][10][11][12][13][14][15] For example, Hong and Chen realized the ring-opening polymerization (ROP) of γ-butyrolactone (γBL), commonly recognized as a "nonpolymerizable" monomer, under readily accessable conditions by utilizing La or Y based organometallic catalysts. 8 Organophosphazene surperbases, such as tert-Bu-P4 and a new cyclic trimetric phosphazene superbase (CTPB, Scheme 1), were later demonstrated to be effective organocataylsts for the ROP of γBL.…”

“…8 Organophosphazene surperbases, such as tert-Bu-P4 and a new cyclic trimetric phosphazene superbase (CTPB, Scheme 1), were later demonstrated to be effective organocataylsts for the ROP of γBL. 9,10 Significantly, the resultant polyester, PγBL, can be selectively and quantitatively depolymerized to its monomer γBL by simply heating the bulk material or chemolysis with a catalyst. A trans-cyclohexyl-ring-fused γBL (3, 4-T6GBL) at the α and β positions with increased ring strain energy relative to γBL was recently developed, which can be readily polymerized into high molecular weight polymer under room temperature and solvent-free conditions.…”