Living Polymerization of Chiral O-Carboxyanhydride of Mandelic Acid and Precise Stereoblock Copolymer Syntheses Using Highly Active OOO-Tridentate Bis(phenolate) Zinc Complexes

Abstract

The synthesis of highly stereoregular poly­(mandelic acid) (PMA) via controllable polymerization is a considerable challenge because of the easy racemization of monomers during polymerization; consequently, precise stereoblock copolymers of PMA have not been reported so far. In this work, highly stereoregular PMA was synthesized through a living ring-opening polymerization of O-carboxyanhydrides (OCAs) of mandelic acid using highly active OOO-tridentate bis­(phenolate)/zinc catalysts. In this polymerization system, the side reaction of racemization was suppressed very well via decreasing the basicity of ligands in zinc complexes. The molecular weight increases linearly as the ratio of monomer to initiator increases and can be high up to 32.5 kg/mol with narrow molecular weight distributions. Meanwhile, for the living polymerization feature, stereodiblock and stereotriblock copolymers with controllable molecular weights were obtained upon sequential one-pot monomer addition within 45 min. Thermal and X-ray diffraction characterizations indicated that these stereoblock copolymers crystallized in a stereocomplex phase with a distinct melting temperature (T m) up to 178 °C, and the solubility behaviors of stereoblock PMAs and enantiomeric homopolymers of PMAs are remarkably different.

Fast Hydrolyzable Constitutional Isomer of Poly(butylene terephthalate) and Its Copolyesters with 1,4-Butanediol

“…Comparing the 1 H NMR spectrum of PBDMS and PB 54 BDM 46 S, a peak at 4.54 ppm (10′) occurred in both spectra (Figure ). In addition, two signals at 4.49 and 3.46 ppm (10″ and 3′) could be seen for PB 54 BDM 46 S. These signals show the presence of unavoidable ether linkages in the polymer backbone by self/cross-condensation of diols at high temperatures. , …”

“…In addition, two signals at 4.49 and 3.46 ppm (10″ and 3′) could be seen for PB 54 BDM 46 S. These signals show the presence of unavoidable ether linkages in the polymer backbone by self/crosscondensation of diols at high temperatures. 33,34 The microstructure of the PB x BDM y S copolyesters was determined by 13 C NMR analysis to clarify the distribution of B and BDM units along the polymer chain. Therefore, the signals of the carbonyl carbon atoms of succinic acid in the S2, showing the total randomness of the microstructure in all cases.…”

Stereocomplexation of Stereoregular Aliphatic Polyesters: Change from Amorphous to Semicrystalline Polymers with Single Stereocenter Inversion

“…PLA-related polymers have been studied extensively for stereocomplexation, − and other examples include polymethylmethacrylates, − polycarbonates, ,− polyhydroxyalkanoates, − polysaccharides, and polycarbodiimides . Notwithstanding these advances, the number of polyester stereocomplexes is modest and much remains to be learned about the factors contributing to stereocomplexation. − …”

Advancing the Development of Recyclable Aromatic Polyesters by Functionalization and Stereocomplexation

“…Moreover, stereocomplexation, the interaction between two complementary stereoregular polymers via Van der Waals forces, dipole–dipole interactions, or hydrogen bonding, has emerged as a powerful approach to modulate the thermal and mechanical properties of materials [42] . Currently, the intensive study has focused on polylactide (PLA) and polymethyl methacrylate (PMMA), [42] and only a few examples were found in other polymer systems such as polycarbonates, polyethers, and polyesters [40, 43–54] . Despite growing interests in the development of high‐performance materials through stereocomplexation, the formation of stereocomplex heavily relies on the availability of enantiopure polymers.…”

“…[42] Currently, the intensive study has focused on polylactide (PLA) and polymethyl methacrylate (PMMA), [42] and only a few examples were found in other polymer systems such as polycarbonates, polyethers, and polyesters. [40,[43][44][45][46][47][48][49][50][51][52][53][54] Despite growing interests in the development of high-performance materials through stereocomplexation, the formation of stereocomplex heavily relies on the availability of enantiopure polymers.…”