We report a new semiaromatic poly­(thioester) obtained through the copolymerization of phthalic thioanhydride and propylene oxide. The reaction was catalyzed by a chromium-based complex in conjunction with [PPN]­Cl, where PPN = bis­(triphenyl­phosphine)­iminium. The reaction temperature exerted a critical influence over catalytic activity as well as the structure of the resulting polymer chain. NMR spectroscopy revealed that the resultant copolymers contained multiple repeating units, including thioester, ester, and thioether–ester linkages, in their main chains due to transesterification, particularly when they were produced at elevated reaction temperatures. The thioester linkage content affected the thermal properties of the polymers. A relatively high glass transition temperature of 69.5 °C was observed in the copolymer containing a large number of thioester linkages obtained at 25 °C. In addition, this sulfur-containing polymer exhibited desirable optical properties, with a refractive index of 1.60.

The copolymerization of epoxides and cyclic thioanhydrides provides a promising method to produce polythioesters and represents an alternative route to the step-growth condensation of dithiols and diacyl chlorides. However, typical binary metal–salen complex/ionic salt systems suffer from an unavoidable transesterification reaction, which degrades the polymer backbone and changes the polymer properties. We herein describe the precise synthesis of polythioesters from the copolymerization of cyclic thioanhydrides and epoxides by an intramolecular acid–base cooperative catalysis strategy, which can significantly suppress side reactions. The bifunctional catalyst composed of Lewis acidic Cr–salen complex with a covalently tethered 1,5,7-triazabicyclo­[4,4,0]­dec-5-ene (TBD, a sterically hindered strong Lewis base) successfully suppressed the transesterification reaction even at low concentrations, yielding polythioesters with completely alternating structures, controlled molecular weights, and low dispersities. Mechanistic studies revealed that polymer chain propagation was predominantly proceeded by intramolecular alternating enchainment between the Lewis acid-activated epoxide and the Lewis base-mediated cyclic thioanhydride.

The precise synthesis of poly(thioester)s with diverse structures is still a significant challenge in the polymeric materials field. Herein, we report a novel approach to the synthesis of well‐defined poly(thioester)s by the controlled alternating copolymerization of cyclic thioanhydrides and episulfides induced by simple organic ammonium salts. Both the cation and anion have strong effects on the copolymerization. [PPN]OAc ([PPN]=bis(triphenylphosphine)iminium) with a bulky cation was proven to be efficient in initiating this polymerization, yielding poly(thioester)s with a completely alternating structure, controlled molecular weight, and narrow polydispersity. The poly(thioester) obtained from succinic thioanhydride and propylene sulfide is a typical semicrystalline material, possessing a high refractive index of up to 1.78. Because it uses readily available monomers, this method is expected to open up a new route to poly(thioester)s with diverse structures and properties.

Synthesis of chiral sulfur-containing polymers was realized for the first time by the asymmetric alternating copolymerization of achiral meso-epoxides with carbonyl sulfide (COS) using catalyst systems based on enantiopure binaphthol-linked dinuclear Co complexes under mild reaction conditions. The resultant poly(monothiocarbonate)s have main-chain chirality and more than 99 % isotacticity. Notably, the stereoregular copolymers are typical semicrystalline thermoplastics with high melting temperatures up to 232 °C. Additionally, these sulfur-containing polymers have good optical properties with refractive indices of up to 1.56 and Abbe's numbers of up to 43.

No abstract

The usage of elemental sulfur (S 8 ) for constructing sulfur-containing polymers is of great significance in terms of sulfur resource utilization or fabrication of high-performance polymers. Currently, the random disassembly of S 8 hinders its direct use in the precise synthesis of sulfur-containing polymers. Herein, we provide an effective strategy for controlling the dismantlement of S 8 to synthesize polydisulfides, a promising category of dynamic bonds containing polymers. In this strategy, the completely alternating copolymerization of one sulfur atom, which is orderly derived from S 8 , with episulfides is achieved with 5,.0]dec-5-ene) as catalyst and[PPN]SbF 6 ([PPN] + is bis(triphenylphosphine)iminium) as cocatalyst. Delightedly, the living-polymerization feature, and the good monomer compatibility allows for the access to diverse polydisulfides. Furthermore, the density functional theory (DFT) was employed to elaborate the copolymerization process.

Various well-defined diblock copolymers with poly(α-methylene−β-butyrolactone) (PM β BL) segment were prepared by salen−aluminum complexes or aminoalkoxybis(phenolate)yttrium amido complex mediated living ring-opening polymerization of racemic α-methylene-β-butyrolactone (rac-M β BL) and different lactones via one-pot, two-step method. These diblock copolymers all consist of semicrystalline and amorphous segments, possessing both a melting point and a glass transition temperature. With the use of simple salenAlMe with bulky (tert-butyldimethylsilyl) groups on the phenolate ortho position as catalyst in conjunction with equivalent benzyl alcohol, M β BL and β-butyrolactone (BL) have nearly identical reactivity in their copolymerization, affording the copolymers P(M β BL-ran-BL) with random distributions of the two monomers. Notably, these copolymers exhibited tunable degradability in the presence of Lewis base, dependent on the M β BL unit content in the random copolymers. Moreover, the vinylidene groups in P(M β BL-ran-BL) copolymers could be further functionalized through radicalinitiated cross-linking reactions and thiol−ene click chemistry, producing functionalized and cross-linking polymers with enhanced thermal property. These strategies will provide enormous possibilities to synthesize diverse well-defined block and random copolymers with designable segments or functional groups.

An aliphatic polyester has been prepared from ethylene oxide and maleic anhydride that undergoes reversible transformation between amorphous (T g = 18 8 8C) and crystalline (T m = 124 8 8C) states through cis-trans isomerization of the C=Cb onds in the polymer backbone without any change in either the molecular weight or dispersity of the polymer.A similar transformation was also observed in chiral unsaturated polyesters formed from enantiopure terminal epoxides,such as epichlorohydrin, phenyl glycidyl ether,and (2,3-epoxypropyl)benzene. These unsaturated polyesters with 100 %E -configuration in the crystalline state were prepared by quantitative isomerization of their Z-configuration analogues in the presence of ac atalytic amount of diethylamine,w hile in the presence of benzophenone,i rradiation with 365 nm UV light resulted in the transformation of about 30 %t rans-alkene to cis-maleate form, thereby affording amorphous polyesters.