Radical polymerization thermodynamics relies on highly exothermic and entropically disfavored monomer propagation. This implies that at high temperatures and/or low monomer concentrations polymerization of some monomers is inaccessible. A series of poly(ethylene glycol) methyl ether methacrylate (PEGMA, Mn = 2080 or 950) macromonomer polymerizations were conducted with varied monomer concentration, ranging from [PEGMA]0 = 50 to 300 mM. ATRP was successful when monomer concentration was above 75 mM in organic media whereas polymerization at [PEGMA]0 = 50 mM resulted in no monomer conversion. This indicates that the macromonomer concentration was below the equilibrium monomer concentration ([M]e). ATRP under high pressure (HP ATRP, p = 3 or 4.5 kbar) allowed to decrease [M]e to much lower level, allowing for polymerization up to high monomer conversion (&gt;99%) at low monomer concentration ([PEGMA]0 = 50 mM), yielding polymers with narrow molecular weight distribution. Effect of solvent and temperature on equilibrium monomer concentration and maximum attainable degree of polymerization was evaluated. Star-like and bottlebrush polymers were prepared by direct polymerization of PEGMA macromonomer via grafting-through method, using atom transfer radical polymerization (ATRP).

Synthesis of star-like and brush polymers via grafting-through of macromonomers by ATRP

251st National Meeting (2016)

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