Organocatalytic Ring-Opening Polymerization of Trimethylene Carbonate To Yield a Biodegradable Polycarbonate

Abstract

In this laboratory experiment, students work in pairs to synthesize a simple aliphatic polycarbonate via ring-opening polymerization of trimethylene carbonate using 1,8-diazabicyclo[5.4.0]undec-7-ene and thiourea as organocatalysts. Following polymer isolation, students cool the material in a dry ice/acetone bath to observe its glasstransition behavior. This experiment is convenient to perform under teaching laboratory conditions and reinforces key concepts learned in second-year undergraduate organic chemistry, for example, nucleophilic acyl substitution, transesterification reactions, and Lewis acidity−basicity. Additionally, the experiment introduces students to polymer chemistry, heterocycles, materials science, and green chemistry. It also covers interesting concepts that are less frequently encountered at the undergraduate level such as biomimetic chemistry, bifunctional catalysis, and polymer−glass transitions.

Liquid Degradable Poly(trimethylene-carbonate-co-5-hydroxy-trimethylene carbonate): An Injectable Drug Delivery Vehicle for Acid-Sensitive Drugs

“…HCl·Et 2 O activates the monomer making it more susceptible to nucleophilic attack by the hydroxyl group on the initiator or the growing chain end . In contrast, DBU is believed to activate the hydroxyl group on the chain end, increasing its nucleophilicity . Finally, Sn­(Oct) 2 is generally considered to act in a coordination-insertion manner, in which the Sn group becomes attached to the growing end of the polymer chain and coordinates with the carbonyl of a carbonate monomer, ultimately causing it to be inserted between the Sn group and the rest of the polymer chain …”

“…35 In contrast, DBU is believed to activate the hydroxyl group on the chain end, increasing its nucleophilicity. 36 Finally, Sn(Oct) 2 is generally considered to act in a coordination-insertion manner, in which the Sn group becomes attached to the growing end of the polymer chain and coordinates with the carbonyl of a carbonate monomer, ultimately causing it to be inserted between the Sn group and the rest of the polymer chain. 37 The polymerization kinetics were followed by monitoring monomer conversion with time for each catalyst via 1 H NMR spectroscopy.…”

From Impossible to Possible: Atom‐Economic Polymerization of Low Strain Five‐Membered Carbonates

“…Ring‐opening polymerization (ROP) of cyclic monomers has been demonstrated as a valid way to synthesize valuable polymer materials [1–21] . The five‐membered propylene carbonate (PC) would be a desirable candidate, benefited from its wide sources (renewable CO 2 ), easy accessibility, low toxicity and broad application [22, 23] .…”

Influence of Chemical Structures on Isodimorphic Behavior of Three Different Copolycarbonate Random Copolymer Series

“…Nevertheless, in this century, studies on aliphatic polycarbonates have shown the importance of this class of materials as versatile biodegradable polymers in the biomedical field, not only due to their high susceptibility to hydrolysis but also because of their biocompatibility and lack of toxicity. [1][2][3][4][5] Historically, polycarbonates have been synthesized by three different methods: ring-opening polymerization (ROP), [6][7][8][9] copolymerization between epoxy and CO2, [10][11][12] and by polycondensation between diols and dimethyl or diphenyl carbonate. 13 The polycondensation route is the most appropriate for large scale production and allows tuning the chemical nature of the aliphatic polycarbonates starting from a wide variety of commercially available diols.…”