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Metallic organophosphates catalyzed bulk ring-opening polymerizations


Aliphatic polyesters are broadly used in biomedical materials, food packaging and drug delivery. Catalytic ring-opening polymerizations (ROP) by dual catalysis associating organocatalysis and metal complex catalysis are powerful strategies toward these valuable polyesters. In an endeavor to combine metal catalysis and organocatalysis in polymerization, we suggested metal salts of organophosphoric acid as bifunctional catalysts in ROPs of cyclic esters and cyclic carbonates. Four metal organophosphates, viz. lithium, sodium, magnesium, and calcium diphenyl phosphates, were evaluated as catalysts for ROPs of trimethylene carbonate (TMC), δ-valerolactone, and lactide with 3-phenyl-1-propanol (PPA) as initiator for obtaining aliphatic polyesters. Magnesium diphenyl phosphate (MgDP) showed relatively high catalytic activity and ideal in control. The molecular weights of PTMCs measured by 1H NMR matched well with the theoretical ones. 1H NMR, 13C NMR, and MALDI-ToF MS measurements demonstrated the initiator and monomer polymerized quantitatively. Bulk polymerizations with various [TMC]0/[PPA]0/[MgDP]0 ratios afforded PTMCs with expected molecular weights (Mn,NMR = 3.21–11.7 kg mol–1) and relatively narrow dispersities (Mw/Mn = 1.16–1.19). Kinetic studies, chain extension experiments and diblock copolymer synthesis were carried out to identify the MgDP-catalyzed ROP proceeded in a controlled/living manner. A bifunctional catalytic mechanism for the MgDP catalyzed ROP was suggested by 1H NMR, 13C NMR and 31P NMR titration experiments. For evaluating the biosafety of PTMC produced in bulk ROP under MgDP catalysis, untreated PTMC samples were tested by MTT assay using L929 cell line. More than 90% relatively cell viabilities exhibited excellent cell compatibility of the PTMCs for potential biomedical applications.

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Publication details

The article was received on 17 Dec 2017, accepted on 08 Jan 2018 and first published on 09 Jan 2018

Article type: Paper
DOI: 10.1039/C7PY02086D
Citation: Polym. Chem., 2018, Accepted Manuscript
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    Metallic organophosphates catalyzed bulk ring-opening polymerizations

    S. Chen, H. Wang, Z. Li, F. Wei, H. Zhu, S. Xu, J. Xu, J. Liu, H. Gebru and K. Guo, Polym. Chem., 2018, Accepted Manuscript , DOI: 10.1039/C7PY02086D

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