Polyelectrolyte complexes (PECs) are ionically crosslinked precipitates obtained by mixing two oppositely charged polyelectrolytes. To further investigate the correlation between chain length and network dynamics of PECs, narrow molecular weight distribution polymers of positive polyelectrolyte poly(methacrylamidopropyltrimethylammonium chloride) (PMAPTAC) and negative polyelectrolyte poly(sodium methacrylate) (PMA-Na) with various molecular weights were synthesized via RAFT polymerization. The linear viscoelastic response for a series of PECs made from pairs of PMA-Na and PMAPTAC was measured in different temperature/salt conditions. Time-temperature superposition, TTS, revealed chain entanglement behaviors for the 3 highest molecular weight coacervate pairs. All characteristic lifetimes were slowed by the "sticky” dynamics of positive, Pol+ and negative, Pol-, pairing. Those results along with detailed compositions of PECs were in agreement with the sticky Rouse model. Time-temperature-salt doping superposition, TTSS, was also achieved by considering the role of salt doping: it can control the overall relaxation behavior of PECs by decreasing the lifetime of Pol+Pol- ionic crosslinks and, by decreasing the number of stickers per chain.

Controlling the network dynamics of polyelectrolyte complexes

2019 Spring National Meeting

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