Aqueous polymerization of protonated 4-vinylpyridine in montmorillonite

The polymerization of protonated 4-vinylpyridine (4-VPH+X−) in the interlayer zone of montmorillonite was studied. Polymerization is critically affected by the degree of surface coverage with a threshold value twice the cation exchange capacity of the mineral. Montmorillonite surfaces show selectivity for protonated 4-vinylpyridine favoring the formation of the quaternized form of the polyvinylpyridine polyelectrolyte. In situ polymerization of 4-VPH+X− in the presence of 10 wt.% or lower sodium montmorillonite in aqueous solution yields exfoliated montmorillonite–polyelectrolyte heterostructures. The rate of polymerization in the presence of delaminated montmorillonite is much faster than in the absence. Mechanisms for intergallery and exogallery polymerization of 4-VPH+X− are described.