Self-Controlled Synthesis of Hyperbranched Polyetherketones From A3 + B2 Approach Via Different Solubilities of Monomers in the Reaction Medium (Preprint)
CHUNGBUK NATIONAL UNIV (KOREA) SCHOOL OF CHEMICAL ENGINEERING
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Hyperbranched polyetherketones PEKs were synthesized via A3 B2 polymerization approach without forming cross-linked networks, because the polymer-forming process based on Friedel-Crafts reaction was kinetically controlled by the solubility difference of monomers in the viscous hydrophilic reaction medium, polyphosphoric acid PPAphosphorous pentoxide P2O5. The hydrophilic trimesic acid as an A3 monomer is soluble in the reaction medium, while hydrophobic diphenyl ether and 1,4-diphenoxybenzene as B2 monomers are marginally soluble. It is hypothesized that the gelation was avoided because of the following two factors i self-regulated feeding of the arylether monomers into the system driven by their poor solubility and phase separation from PPA P2O5 medium ii reaction-medium-induced isolation of growing macromolecules promoted by the high bulk viscosity. Both polymerization experiments based on equimolar or equifunctional stoichiometry A3 B2 resulted in completely soluble hyperbranched PEKs in polar aprotic solvents when these polymers contained a little amount of solvent residues and only in strong acids if they were rigorously dried. The structural analysis by using MALDI-TOF mass spectroscopy in the low molar mass region provided further confirmation that there was no trace of networks various sizes of cyclics were detected instead.
- Polymer Chemistry
- Physical Chemistry