Structural effects of type of intercalant in poly (4-vinylpyridine) nanocomposites: compatible homopolymer or block copolymer

4-vinylpyridine monomer was mixed with organophilic montmorillonite (MMT) clay and polymerized in the presence of free-radical initiator. MMT clay was rendered organophilic by means of ion-exchanging sodium cations for low-molecular-weight quaternized poly(4-vinylpyridine) (P4VP) homopolymer and diblock copolymers of styrene and quaternized 4-vinylpyridine (SVP) with different sequence lengths. The swelling behaviour of the MMT clay was studied by X-ray diffraction (XRD). After the cation exchange, the resulting organophilic clays showed an expansion of interlayer distance indicating the nanoscale ordering of intercalant polymer and MMT layers. The nanocomposite materials, when moulded, exhibited improved thermal stability and dynamic mechanical properties compared with neat P4VP. The composite, having longer ionic segments in its organophilic MMT, showed exfoliated nanocomposite structure as well as higher stiffness and damping properties at higher temperatures even for MMT loading as low as 2 wt%. (C) 2006 Society of Chemical Industry.