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Synthesis of High Molecular Weight Stereo-Di-Block Copolymers Driven by a Co-Initiator Free Catalyst.

ABSTRACT: Stereo-diblock copolymers of high molecular weight polylactide (PLA) were synthetized by the one pot-sequential addition method assisted by a heteroscorpionate catalyst without the need of a co-initiator. The alkyl zinc organometallic heteroscorpionate derivative (Zn(Et)(κ³-bpzteH)] (bpzteH = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-para-tolylethoxide) proved to assist in the mechanism of reaction following a coordination-insertion process. Kinetic studies along with the linear correlation between monomer and number average molecular weight (M_n) conversion, and the narrow polydispersities supported the truly living polymerization character of the initiator, whereas matrix-assisted laser desorption/Ionization-time of flight (MALDI-TOF) studies showed a very low order of transesterification. The high stereo-control attained for the afforded high molecular weight derivatives was revealed by homonuclear decoupled ¹H NMR spectra and polarimetry measurements. The nanostructure of the PLA derivatives was studied by both wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) and the stereocomplex phase of the PLA stereo-diblock copolymers was successfully identified.

SUBMITTER: Moya-Lopez C

PROVIDER: S-EPMC8779727 | biostudies-literature |

REPOSITORIES: biostudies-literature

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