Enantiopure Isotactic PCHC Synthesized by Ring-Opening Polymerization of Cyclohexene Carbonate

Abstract

International audienceThe ring-opening polymerization (ROP) of racemic trans-cyclohexene carbonate (rac-CHC) and enantiopure trans-(R,R)-CHC is successfully carried out with various catalyst systems. Poly(cyclohexene carbonate) (PCHC) with a slight isotactic bias (Pm = ca. 60–76%) is obtained by ROP of rac-CHC catalyzed by zinc diaminophenolate, zinc β-diketiminate, yttrium bis(phenolate), or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) in combination with an alcohol as a co-initiator. Purely isotactic PCHC is synthesized for the first time via ROP of enantiopure (R,R)-CHC with a zinc/benzyl alcohol catalyst system. All reactions proceed without decarboxylation, affording well-defined PCHCs with Mn,NMR up to 17 000 g mol–1 and ĐM = ca. 1.2. Purely isotactic PCHC is semicrystalline, with Tg = 130 °C, Tc = 162 °C, and Tm = 248 °C. DFT computations further highlight the significant favorable impact of the trans-cyclohexane ring-strain to enable the ROP of CHC, as opposed to meso-CHC which is unreactive

Effect of supercritical CO2 on the copolymerization behavior of cyclohexene oxide/CO2 and copolymer properties with DMC/Salen‐Co(III) catalyst system

“…Through assignment of the sole contribution of r‐centered tetrads ([rrr], [rrm], [mrm]) were at δ = 153.9 ppm, conversely the peaks at δ = 153.7 ppm were assigned to the central carbonyl carbons of m‐centered tetrads ([mmm]), with a series of lower intensity resonances at δ = 153.3–153.1 ppm. The nonequivalent methylene carbons in the PCHC backbone at δ = 29.8 and 23.2 ppm, corresponding to the mm triad, as reported in the literature . The chain structure from the scCO 2 synthesized PCHC shows us that the combined DMC/salen‐Co(III) catalyst system has poor stereo‐control over CHO insertion into the main polymer chain, comparing to the obtained PCHC with 81% r‐centered tetrads was obtained in Coates' work …”

Dinuclear Metal Complex-Mediated Formation of CO2-Based Polycarbonates

“…29) [162]. The complex was thermally robust and showed high activity (3,500 h À1 ), at 90 C whilst retaining good polymer selectivity (~90%). Under the same conditions, an analogous catalyst/cocatalyst combination showed low activity and poor selectivity for polymer.…”

“…It should be noted that the five-membered-ring cyclic carbonates generally cannot re-enter into polymerisation cycles as their ringopening polymerisation is thermodynamically unfavourable. This year, the first example of the polymerisation of five-membered cyclic carbonate was reported by Carpentier and Guillaume and co-workers [90]. In that case, the polymerisation is thermodynamically possible because a highly strained trans-cyclohexene carbonate was applied as the monomer.…”

Research Progress of Biodegradable Polyester Polyols Based on Ring-Opening Polymerization of Cyclohexene Carbonate

“…4. Coordination-insertion mechanisms in ROP of lactide [77] The ring-opening polymerization (ROP) of racemic trans-cyclohexene carbonate (rac-CHC) and enantiopure trans-(R, R)-CHC is successfully obtained by William et al [54]. Poly(cyclohexene carbonate) (PCHC) (Fig.…”

“…5) is obtained by ROP of rac-CHC catalyzed by zinc diaminophenolate, zinc β-diketiminate, yttrium bis(phenolate), or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) in combination with an alcohol as a coinitiator. [54] And the reaction proceeds without decarboxylation, affording PCHC with the molecular weight up to 17000 g/mol and ĐM = ca. 1.2, realizing the first synthesis of a purely isotactic PCHC, which is a semicrystalline polycarbonate featuring a high T g of 130 °C.…”