Radical polymerization behavior of hydroxystyrenes

Homopolymerizations of m‐ and p‐hydroxystyrene and their copolymerizations with styrene and methyl methacrylate by use of azobisisobutyronitrile as initiator were investigated, and the results were compared with those obtained previously o‐hydroxystyrene. Intrinsic viscosities of m‐ and p‐hydroxystyrene polymers obtained by bulk and solution polymerizations were ca. 2 to 3 times larger than those of o‐hydroxystyrene polymers obtained by the similar conditions. The structures of the polymers thus produced were investigated by infrared and ultraviolet spectroscopy. These studies suggested that all of the homopolymers consisted mainly of structures of normal vinyl type polymer. Rp was proportional to [I]0.52 for m‐hydroxystyrene and to [I]0.50 for p‐hydroxystyrene, for o‐hydroxystyrene Rp was proportional to [I]0.72. A reasonable chain transfer mechanism for these monomers was postulated. The apparent activation energies of polymerization for m‐ and p‐hydroxystyrene were found to be 20.1, and 18.0 kcal/mole, respectively, compared to the value of 21.5 kcal/mole for o‐hydroxystyrene. Monomer reactivity ratios and Q − e values for m‐ and p‐hydroxystyrene were determined, and the results were also compared with the case of o‐hydroxystyrene. Copolymerization generally gave a polymer with relatively high intrinsic viscosity, even in the case of o‐hydroxystyrene.