title: The Quest for Converting Biorenewable Bifunctional α-Methylene-γ-butyrolactone into Degradable and Recyclable Polyester: Controlling Vinyl-Addition/Ring-Opening/Cross-Linking Pathways.
abstract: α-Methylene-γ-butyrolactone (MBL), a naturally occurring and biomass-sourced bifunctional monomer, contains both a highly reactive exocyclic C═C bond and a highly stable five-membered γ-butyrolactone ring. Thus, all previous work led to exclusive vinyl-addition polymerization (VAP) product P(MBL)VAP. Now, this work reverses this conventional chemoselectivity to enable the first ring-opening polymerization (ROP) of MBL, thereby producing exclusively unsaturated polyester P(MBL)ROPwith Mnup to 21.0 kg/mol. This elusive goal was achieved through uncovering the thermodynamic, catalytic, and processing conditions. A third reaction pathway has also been discovered, which is a crossover propagation between VAP and ROP processes, thus affording cross-linked polymer P(MBL)CLP. The formation of the three types of polymers, P(MBL)VAP, P(MBL)CLP, and P(MBL)ROP, can be readily controlled by adjusting the catalyst (La)/initiator (ROH) ratio, which is determined by the unique chemoselectivity of the La-X (X = OR, NR2, R) group. The resulting P(MBL)ROPis degradable and can be readily postfunctionalized into cross-linked or thiolated materials but, more remarkably, can also be fully recycled back to its monomer thermochemically. Computational studies provided the theoretical basis for, and a mechanistic understanding of, the three different polymerization processes and the origin of the chemoselectivity.
authors.affiliation: Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Tang
authors.affiliation: Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States.
authors.forename: Miao
authors.initials: M
authors.lastname: Hong
authors.affiliation: Physical Sciences and Engineering Division, Kaust Catalysis Center, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
authors.forename: Laura
authors.initials: L
authors.lastname: Falivene
authors.affiliation: Dipartimento di Chimica e Biologia, Università di Salerno , Via Papa Paolo Giovanni II, I-84084, Fisciano, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Caporaso
authors.affiliation: Physical Sciences and Engineering Division, Kaust Catalysis Center, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.|Dipartimento di Chimica e Biologia, Università di Salerno , Via Papa Paolo Giovanni II, I-84084, Fisciano, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Cavallo
authors.affiliation: Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523-1872, United States.
authors.forename: Eugene Y-X
authors.initials: EY
authors.lastname: Chen
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000737:chemistry; D000475:Alkenes / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011091:Polyesters / Q000737:chemistry*; D058105:Polymerization; D013816:Thermodynamics
chemical_list: D000475:Alkenes; D011091:Polyesters; C014096:alpha-methylene gamma-butyrolactone; D015107:4-Butyrolactone