- Hyperbranched polyphosphoesters with reactive end groups synthesized via acyclic diene metathesis polymerization and their transformation to crosslinked nanoparticles
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A novel hyperbranched polyphosphoester (HBPPE) was prepared by acyclic diene metathesis (ADMET) polymerization of an AB2 monomer using the second-generation Hoveyda-Grubbs catalyst. IR analysis, gel permeation chromatography with multiangle laser light scattering, and NMR spectroscopy confirmed their controlled synthesis. The effect of the ADMET polymerization time in the thermal properties of HBPPEs was studied and their thermal degradation and flame-retardant properties were evaluated. These reactive HBPPEs were used to synthesize polyphosphoesters nanoparticles by intramolecular crosslinking of the end acrylate groups in dilute solution. The successful preparation of this new type of polymer nanoparticles was proven by NMR spectroscopy and gel permeation chromatography. The morphologies of nanostructures were investigated via dynamic light scattering, atom force microscopy, and transmission electron microscopy. The results revealed that the crosslinked nanoparticles, which have a comparatively uniform size, were stable and reproducible in organic solvents.
- Ding, Liang,Qiu, Jun,Lu, Rong,Zheng, Xueqin,An, Jing
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- Cyclic polyphosphoesters synthesized by acyclic diene metathesis polymerization and ring closing metathesis
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This article describes the synthesis of cyclic polyphosphoester (PPE) by the ring-closing metathesis (RCM) of different difunctional linear PPEs. Linear PPE precursors were prepared through a selective head-to-tail acyclic diene metathesis polymerization of phenyl dienephosphate monomer using 2-hydroxyethyl acrylate as a selective chain terminator, followed by the transformation of the terminal acrylate functional group into a hydroxyl group utilizing a thiol-Michael addition click reaction. These products were then reacted with the corresponding acyl chloride containing a vinyl end group. The subsequent end-to-end intramolecular coupling reaction was performed under highly dilute conditions. The successful transformation of the linear PPE precursors to cyclic PPE was confirmed by NMR spectroscopy and gel permeation chromatography. The thermal and flame retardant properties of linear and cyclic PPEs were investigated, and their thermal degradation and flame retardance were evaluated, as these are important features for future applications.
- Ding, Liang,Lu, Rong,An, Jing,Zheng, Xueqin,Qiu, Jun
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