title: Poly(thioester) by Organocatalytic Ring-Opening Polymerization.
abstract: Organocatalysts typically used for the ring-opening polymerization (ROP) of cyclic ester monomers are applied to a thiolactone,ε-thiocaprolactone (tCL). In the absence of an H-bond donor, a nucleophilic polymerization mechanism is proposed. Despite the decreased ability of thioesters and thiols (versus esters and alcohols) to H-bond, H-bonding organocatalysts-a thiourea in combination with an H-bond accepting base-are also effective for the ROP of tCL. The increased nucleophilicity of thiols (versus alcohols) is implicated in the increasedMw/Mnof the poly(thiocaprolactone) versus poly(caprolactone), but deleterious transesterification is suppressed in the presence of a thiourea. The thioester monomer, tCL, is shown to be thermodynamically similar toε-caprolactam but kinetically similar toε-caprolactone.
authors.affiliation: Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Bannin
authors.affiliation: Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Kiesewetter