Preparation and evaluation of composites from montmorillonite and some heterocyclic polymers. 1: Poly(N-vinylcarbazole) montmorillonite nanocomposite system

The cationic polymerization of N-vinylcarbazole (NVC) can be initiated directly by montmorillonite (MMT) The polymerization has been studied with MMT in solid phase and NVC at melting temperature ( > 64 degrees C) or in benzene solution at 50 degrees C. By repeated benzene extraction of the PNVC-MMT reaction product, an intercalcate of PNVC in MMT has been isolated. I.r. spectral analysis endorses the presence of PNVC in the intercalate. XRD analysis confirms expansion of d(001) spacing of MMT indicating the intercalcation of PNVC in the MMT layer. TEM analysis indicates the particle size of PNVC-MMT intercalate to be 33 +/- 10 nm. Thermogravimetric stability studies indicate, PNVC stability is much enhanced upon intercalcation confirming formation of intimately associated microaggregates of PNVC and MMT. Thus PNVC is completely lost around 700 degrees C but PNVC-MMT composite undergoes 19.5% loss at 999 degrees C the residue being MMT. From these t.g.a. data, it has been calculated that PNVC-MMT intercalate contains 6.35%. PNVC per gm of MMT. D.c. conductivity of PNVC-MMT composite (10(-6) S/cm) is 10(10) times greater than that for PNVC (10(-16) Slcm). (C) 1998 Elsevier Science Ltd. All rights reserved.