An Investigation on the Production of Random Copolymer with Monothiocarbonate and Trithiocarbonate Units over Cyclic Thiocarbonate via Metal‐free Catalysis

Abstract

Summary of main observation and conclusion Synthesis of poly(thiocarbonate)s from the copolymerization of epoxides and carbon disulfide (CS2) remains a tough challenge, due to inevitable oxygen‐sulfur atom scrambling process. In this work, we utilized the oxygen‐sulfur exchange reaction (O‐S ER) to synthesize a random copolymer with monothiocarbonate and trithiocarbonate units from CS2 and phenyl glycidyl ether (PGE) via metal‐free Lewis pairs. The copolymers contained monothiocarbonate and trithiocarbonate units of which the molar fraction could be tuned by varying either the types of Lewis pairs or the reaction temperature. Keeping track on the intermediate provided an insight in the process of O‐S ER and thus gave a hint to control the product structure. Production and consumption of phenyl thioglycidyl ether was the key process to regulate the chain structure. Remarkably, the oxygen atoms of PGE could be excluded out of the chain, resulting in the nearly complete production of poly(trithiocarbonate)s. Correspondingly, the refractive index of this kind of copolymer could be regulated in a wide range of 1.73—1.79 (at 590 nm).

Lithium achieves sequence selective ring-opening terpolymerisation (ROTERP) of ternary monomer mixtures

“…15–17 Sulfur analogous are also accessible such as polythiocarbonate from CS 2 /(epoxide or thiirane) and polythioesters from thioanhydride/(epoxide or thiirane) ROCOP. 18–31 Such sulfur rich polymers are attractive high-refractive index materials that can show improved crystallinity and degradability over their all-oxygen analogues and in some cases enable chemical polymer to monomer recycling. 32–39…”

Borane catalysis for epoxide (co)polymerization

“…In 2020, Zhang and co-workers have studied this, focusing on PGE as epoxide component. 96 PGE was specifically selected because its reactivity with COS was found to be somewhat sluggish. 92 This feature was hoped to simplify the array of different linkage motifs which can occur when copolymerizing cyclic ethers with CS 2 under the excessive O/S scrambling (COS is an important intermediate).…”

Cooperative taming of CS2/oxetane copolymerisation: Consequences of main-chain sulfuration on polymer properties and catalysis

“…as well as all-oxygen carbonate (-O-C(=O)-O-OOO) and thioether links are always obtained in addition to small molecule by-products, such as different cyclic (thio)carbonates, thiiranes and COS instead of the expected poly(dithiocarbonates) from alternating ROCOP as demonstrated, assigned and rationalised by the groups of Wan, Zhang and Darensbourg. [30][31][32][33][34][35][36][37][38] Polymer selectivities versus cyclic heterocarbonates range from 30 to 80% in which dithiocarbonate links from alternating copolymerisation make up the minor (typically 0 -30 %) fraction. Product distribution and polymer composition strongly depend on the exact reaction conditions making material properties unpredictable and necessitating time-consuming purification steps.…”