A novel reactive phosphonium-containing polyelectrolyte with multiple reactivities: monomer synthesis, RAFT polymerization and post-polymerization modifications
Reactive polyelectrolyte can be defined as a kind of functional polymer which possesses not only the basic properties of polyelectrolyte but also wide post-polymerization modification possibilities by various reactions. In this paper, we first introduced a well-defined phosphonium polyelectrolyte containing three reactive hydroxymethyl groups which were bonded directly to phosphorus atom. A novel phosphonium-containing monomer, namely 4-vinylbenzyl(trihydroxymethylphosphonium) chloride (VBzTHPC), was designed and synthesized from tetrakis(hydroxymethyl) chloride (THPC), a commercial product from phosphine (PH3) tail gas. The efficient, controlled polymerization of VBzTHPC was achieved by using reversible addition-fragmentation chain transfer (RAFT) polymerization in N,N’-dimethylformamide (DMF). First-order linear kinetic plots were observed with different molecular weights and narrow molecular weight distributions (Mw/Mn typically below 1.30) by adjusting the polymerization conditions. These adjustments included the temperature (60 and 70°C), monomer concentration (20, 25 and 33wt%), types of initiator (AIBN and AIVN) and chain transfer agent. The hydroxymethyl-containing polyelectrolyte was readily converted to corresponding non-electrolytic linear polymer with alkali treatment under mild conditions, and took substitution reaction with secondary amine compounds without any catalysts. In addition, the water-soluble polyelectrolyte shows high reactivity with metal ions and silver particles (Dh=104nm) can be efficiently obtained with PVBzTHPC as reducing agent.