POLYMERIZATION OF ADSORBED MONOLAYERS .4. 2-DIMENSIONAL STRUCTURE OF INSERTION POLYMERS

Insertion poly(methyl methacrylate) homopolymers and copolymers with methacrylic acid were prepared from the corresponding monomers adsorbed as monolayers on the surface of sodium montmorillonite. The polymerization was carried out with γ-rays or benzoyl peroxide with or without crosslinking agent. Both insertion homopolymers and copolymers are associated in packets" containing several macromolecules. The architecture of these aggregates is reminiscent of the elementary crystallite of montmorillonite. The aggregates can be dissociated irreversibly into individual macromolecules which display unusual light scattering and viscosity behavior. Only insertion homopolymers or copolymers prepared with benzoyl peroxide and without crosslinking agent follow the usual viscosity molecular weight relationship for linear (poly(methyl methacrylate). Insertion polymers or copolymers prepared with γ-rays display unusual viscosity and light scattering properties irrespectively of the presence of crosslinking agent. A compact two-dimensionally crosslinked architecture is compatible with the properties observed. This hypothesis is confirmed by the hydrodynamic properties of sodium salts of crosslinked insertion copolymers in methanol and in water. The polyelectrolytes appear to be extensively crosslinked and to display an oblate macromolecular conformation upon expansion. © 1969."