Semiaromatic Poly(thioester) from the Copolymerization of Phthalic Thioanhydride and Epoxide: Synthesis, Structure, and Properties

Abstract

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.

Heterocycle/Heteroallene Ring‐Opening Copolymerization: Selective Catalysis Delivering Alternating Copolymers

“…Very recently the sulphur analogues of anhydride/epoxide ROCOP were reported to deliver poly(thioester) structures inaccessible by conventional routes. [191][192][193] Figure 29: ROCOP of thioanhydride with epoxides or thiiranes.…”

“…Phthalic thioanhydride (PTA)/PO ROCOP using Cr III ‐salen/PPNCl catalysts showed good performance (TOF 30–1420 h −1 , 25–100 °C, 0.1–0.001 mol %, M n =18.2–60.1 kg mol −1 ) [192] . The polymer contained thioester, ester, and thioether linkages, was regio‐random, and lacked long‐range order.…”

Electron rich (salen)AlCl catalysts for lactide polymerisation: Investigation of the influence of regioisomers on the rate and initiation efficiency

“…Yet ring-opening a highly strained epoxide is an easier target than LA, [30][31][32] a phenomenon that has successfully been exploited in various polymerisations. [33][34][35][36][37][38] Thomas, Maron et al demonstrated that the Jacobsen (salen)AlCl complex can initiate LA ROP via epoxide ringopening (Figure 1, left) in the presence of an onium salt (PPNCl) and excess epoxide. [39] We recently showed that external Lewis bases can be avoided by incorporating electron-donating diaminosubstituents into the salen scaffold (Figure 1 right).…”

Heterocycle/Heteroallene Ring‐Opening Copolymerization: Selective Catalysis Delivering Alternating Copolymers

“…Very recently,t he sulfur analogues of anhydride/ epoxide ROCOP were reported to deliver poly(thioester) structures inaccessible by conventional routes. [191][192][193] Lu and co-workers reported ROCOP of thiiranes with stearic (STA) or glutaric thioanhydride (GTA) using Lewis base/PPNX catalysts (Figure 29). [191] Them ost effective was PPNOAc, which delivered polymers quickly with molar masses close to theoretical expectations (TOF 787 h À1 ,2 5 8 8C, 0.4 mol %, M n = 53.6 kg mol À1 ,for STA/PS;F igure 30).…”

“…Phthalic thioanhydride (PTA)/PO ROCOP using Cr IIIsalen/PPNCl catalysts showed good performance (TOF 30-1420 h À1 ,2 5-100 8 8C, 0.1-0.001 mol %, M n = 18.2-60.1 kg mol À1 ). [192] Thep olymer contained thioester,e ster, and thioether linkages,w as regio-random, and lacked longrange order.T he linkage scrambling was attributed to intramolecular and/or intermolecular transesterification reactions akin to CS 2 /epoxide ROCOP.S crambling increased with temperature and influenced the polymersg lass transition temperature (T g = 62 8 8Cf rom reactions at 100 8 8C, T g = 70 8 8C from reactions at 25 8 8C, both with M n % 18 kg mol À1 ). A tethered Lewis base/Cr III -salen catalyst showed fewer transesterifications (TOF 94-567 h À1 ,0 .1-0.01 mol %, 25-70 8 8C, M n = 15.9-49.7 kg mol À1 ).…”