title: Precision Aliphatic Polyesters with Alternating Microstructures via Cross-Metathesis Polymerization: An Event of Sequence Control.
abstract: Sequence-regulated polymerization is realized upon sequential cross-metathesis polymerization (CMP) and exhaustive hydrogenation to afford precision aliphatic polyesters with alternating sequences. This strategy is particularly suitable for the arrangement of well-known monomer units including glycolic acid, lactic acid, and caprolactic acid on polymer chain in a predetermined sequence. First of all, structurally asymmetric monomers bearing acrylate and α-olefin terminuses are generated in an efficient and straightforward fashion. Subsequently, cross-metathesis (co)polymerization of M1 and M2 using the Hoveyda-Grubbs second-generation catalyst (HG-II) furnishes P1-P3, respectively. Finally, hydrogenation yields the desired saturated polyesters HP1-HP3. It is noteworthy that the ε-caprolactone-derived unit is generated in situ rather than introduced to tailor-made monomers prior to CMP. NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) results verify the microstructural periodicity of these precision polyesters. Differential scanning calorimetry (DSC) results reflect that polyesters without methyl side groups exhibit crystallinity, and unsaturated polyester samples show higher glass transition temperatures than their hydrogenated counterparts owing to structural rigidity.
authors.affiliation: Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
authors.forename: Zi-Long
authors.initials: ZL
authors.lastname: Li
authors.affiliation: Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
authors.forename: Fu-Rong
authors.initials: FR
authors.lastname: Zeng
authors.affiliation: Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
authors.forename: Ji-Mei
authors.initials: JM
authors.lastname: Ma
authors.affiliation: Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
authors.forename: Lin-Hao
authors.initials: LH
authors.lastname: Sun
authors.affiliation: Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
mesh_terms: D002152:Calorimetry, Differential Scanning; D002208:Caproates; D007783:Lactones; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry; D058105:Polymerization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D002208:Caproates; D007783:Lactones; D011091:Polyesters; C121056:caprolactone
keywords: alternation; metathesis; microstructures; polyesters; structure-property relations